Lincoln Electric PRO-CUT 25 User Manual

SVM149-A

October, 2006

Safety Depends on You

Lincoln arc welding and cutting
equipment is designed and built
with safety in mind. However,
your overall safety can be
increased by proper installation
. . . and thoughtful operation on
your part. DO NOT INSTALL,

OPERATE OR REPAIR THIS
EQUIPMENT WITHOUT READ­ING THIS MANUAL AND THE
SAFETY PRECAUTIONS CON­TAINED THROUGHOUT. And,

most importantly, think before
you act and be careful.

SERVICE MANUAL

For use with machine code numbers 10661

PRO-CUT 25

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• World's Leader in Welding and Cutting Products •

Copyright © 2006 Lincoln Global Inc.

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PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH. KEEP CHILDREN
AWAY. PACEMAKER WEARERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE OPERATING.

Read and understand the following safety highlights. For additional safety information it is strongly recommended that you pur­chase a copy of “Safety in Welding & Cutting - ANSIStandard Z49.1” from the American Welding Society, P.O. Box 351040,
Miami, Florida 33135 or CSA Standard W117.2.

BE SURE THAT ALL INSTALLATION, OPERATION, MAINTENANCE, AND REPAIR PROCEDURES ARE
PERFORMED ONLY BY QUALIFIED INDIVIDUALS.

CUTTING SPARKS can
cause fire or explosion.

4.a..Remove fire hazards from the plasma cutting
or gouging area. If this is not possible, cover them
to prevent the cutting or gouging sparks from

starting a fire. Remember that welding sparks
and hot materials from plasma cutting or gouging can easily
go through small cracks and openings to adjacent areas.
Avoid cutting or gouging near hydraulic lines. Have a fire
extinguisher readily available.

4.b. Where compressed gases are to be used at the job site, spe­cial precautions should be used to prevent hazardous situa­tions. Refer to “Safety in Welding and Cutting” (ANSI Standard
Z49.1) and the operating information for the equipment being
used.

ARC RAYS can burn.

2.a. Use safety glasses and a shield with the prop­er filter and cover plates to protect your eyes from
sparks and the rays of the arc when performing or
observing plasma arc cutting or gouging.
Glasses,headshield and filter lens should conform
to ANSI Z87. I standards.

2.b. Use suitable clothing including gloves made from durable
flame-resistant material to protect your skin and that of your
helpers from the arc rays.

2.c. Protect other nearby personnel with suitable non-flammable
screening and/or warn them not to watch the arc nor expose
themselves to the arc rays or to hot spatter or metal.

ELECTRIC SHOCK can kill.

1.a. The electrode and work (or ground) circuits
are electrically “hot” when the power source is on.
Do not touch these “hot” parts with your bare skin
or wet clothing. Wear dry, hole-free gloves to insu­late hands.

1.b. When the power source is operating voltages in excess of 250
volts are produced. This creates the potential for serious elec­trical shock - potentially even fatal.

1.c. Insulate yourself from work and ground using dry insulation.
When cutting or gouging in damp locations, on metal frame­work such as floors, gratings or scaffolds and when in posi­tions such as sitting or lying, make certain the insulation is
large enough to cover your full area of physical contact with
work and ground.

1.d. Always be sure the work cable makes a good electrical con­nection with the metal being cut or gouged. The connection
should be as close as possible to the area being cut or
gouged.

1.e. Ground the work or metal to be cut or gouged to a good elec­trical (earth) ground.

1.f. Maintain the plasma torch, cable and work clamp in good, safe
operating condition. Replace damaged insulation.

1.g. Never dip the torch in water for cooling or plasma cut or gouge
in or under water.

1.h. When working above floor level, protect yourself from a fall
should you get a shock.

1.i. Operate the pilot arc with caution. The pilot arc is capable of
burning the operator, others or even piercing safety clothing.

1.j. Also see Items 4c and 6.

PLASMA CUTTING or GOUGING can be hazardous.

FUMES AND GASES
can be dangerous.

3.a. Plasma cutting or gouging may produce
fumes and gases hazardous to health. Avoid
breathing these fumes and gases. When cutting
or gouging, keep your head out of the fumes. Use
enough ventilation and/or exhaust at the arc to

keep fumes and gases away from the breathing zone. When

plasma cutting or gouging on lead or cadmium plated
steel and other metals or coatings which produce highly
toxic fumes keep exposure as low as possible and below
Threshold Limit Values (TLV) using local exhaust or
mechanical ventilation. In confined spaces or in some
circumstances, outdoors, a respirator may be required.
Additional precautions are also required when plasma
cutting or gouging on galvanized steel.

3. b. The operation of plasma cutting or gouging fume control
equipment is affected by various factors including proper use
and positioning of the equipment, maintenance of the equip­ment and the specific procedure and applicaiton involved.
Worker exposure level should be checked upon installation
and periodically thereafter to be certain it is within applicable
OSHA PEL and ACGIH TLV limits.

3.c. Do not use plasma cutting or gouging equipment in locations

near chlorinated hydrocarbon vapors coming from degreas­ing, cleaning or spraying operations. The heat and rays of the
arc can react with solvent vapors to form phosgene, a highly
toxic gas, and other irritating products.

3.d. Gases used for plasma cutting and gouging can displace air

and cause injury or death. Always use enough ventilation,
especially in confined areas, to insure breathing air is safe.

3.e. Read and understand the manufacturer’s instructions for this

equipment and follow your employer’s safety practices.

Aug. ‘06

i

SAFETY

i

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4.c. When not cutting or gouging, make certain no part of the elec­trode circuit is touching the work or ground. Accidental contact
can cause overheating and create a fire hazard.

4.d. Do not cut or gouge tanks, drums or containers until the proper
steps have been taken to insure that such procedures will not
cause flammable or toxic vapors from substances inside. They
can cause an explosion even though they have been “cleaned.”
For information purchase “Recommended Safe Practices for
the Preparation for Welding and Cutting of Containers and
Piping That Have Held Hazardous Substances”, A WSF4.1 from
the American Welding Society (see address above).

4.e. Vent hollow castings or containers before heating, cutting or
gouging. They may explode.

4.f. Do nor fuel engine driven equipment near area where plasma
cutting or gouging.

4.g. Sparks and spatter are thrown from the plasma arc. Wear safe­ty glasses, ear protection and oil free protective garments such
as leather gloves, heavy shirt, cuffless trousers, high shoes
and a cap over your hair. Wear ear plugs when cutting or goug­ing out of position or in confined places. Always wear safety
glasses with side shields when in a cutting or gouging area.

4.h. Connect the work cable to the work as close to the cutting or
gouging area as practical. Work cables connected to the build­ing framework or other locations away from the cutting or goug­ing area increase the possibility of the current passing through
lifting chains, crane cables or other alternate circuits. This can
create fire hazards or overheat lifting chains or cables until they
fail.

FOR ELECTRICALLY
powered equipment.

6.a. Turn off input power using the disconnect
switch at the fuse box before working on the
equipment.

6.b. Install equipment in accordance with the U.S. National
Electrical Code, all local codes and the manufacturer’s rec­ommendations.

6.c. Ground the equipment in accordance with the U.S. National
Electrical Code and the manufacturer’s recommendations.

CYLINDER may explode
if damaged.

5.a. Use only compressed gas cylinders contain­ing the correct gas for the process used and
properly operating regulators designed for the

gas and pressure used. All hoses, fittings, etc.
should be suitable for the application and maintained in good
condition.

5.b. Always keep cylinders in an upright position securely chained
to an undercarriage or fixed support.

5.c. Cylinders should be located:

• Away from areas where they may be struck or subjected to

physical damage.

• Asafe distance from plasma cutting or gouging, arc weld-

ing operations and any other source of heat, sparks,
or flame.

5.d. Never allow any part of the electrode, torch or any other elec­trically “hot” parts to touch a cylinder.

5.e. Keep your head and face away from the cylinder valve outlet
when opening the cylinder valve.

5.f. Valve protection caps should always be in place and hand
tight except when the cylinder is in use or connected for use.

5.g. Read and follow the instructions on compressed gas cylin­ders, associated equipment, and CGA publication P-l,
“Precautions for Safe Handling of Compressed Gases in
Cylinders,”available from the Compressed Gas Association
1235 Jefferson Davis Highway, Arlington, VA22202.

Apr. ‘93

ELECTRIC AND MAGNETIC FIELDS

may be dangerous

8.a. Electric current flowing through any conduc­tor causes localized Electric and Magnetic Fields
(EMF). Cutting or gouging current creates EMF
fields around torch cables and cutting machines.

8.b. EMF fields may interfere with some pace­makers, so operators having a pacemaker
should consult their physician before cutting or

gouging.

8.c. Exposure to EMF fields during cutting or gouging may have
other health effects which are now not known.

8d. All operators should use the following procedures in order to

minimize exposure to EMF fields from the cutting or gouging
circuit:

8.d.1. Route the torch and work cables together - Secure
them with tape when possible.

8.d.2. Never coil the torch cable around your body.

8.d.3. Do not place your body between the torch and
work cables. If the torch cable is on your right side,

the work cable should also be on your right

side.

8.d.4. Connect the work cable to the workpiece as close as
possible to the area being cut or gouged.

8.d.5. Do not work next to cutting power source.

PLASMA ARC can injure.

7.a. Keep your body away from nozzle and
plasma arc.

7.b. Operate the pilot arc with caution. The pilot arc is capable of
burning the operator, others or even piercing safety clothing.

ii

SAFETY

ii

SAFETY

iii iii

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PRÉCAUTIONS DE SÛRETÉ

Pour votre propre protection lire et observer toutes les instructions
et les précautions de sûreté specifiques qui parraissent dans ce
manuel aussi bien que les précautions de sûreté générales suiv­antes:

Sûreté Pour Soudage A L’Arc

1. Protegez-vous contre la secousse électrique:

a. Les circuits à l’électrode et à la piéce sont sous tension

quand la machine à souder est en marche. Eviter toujours
tout contact entre les parties sous tension et la peau nue
ou les vétements mouillés. Porter des gants secs et sans
trous pour isoler les mains.

b. Faire trés attention de bien s’isoler de la masse quand on

soude dans des endroits humides, ou sur un plancher met­allique ou des grilles metalliques, principalement dans
les positions assis ou couché pour lesquelles une grande
partie du corps peut être en contact avec la masse.

c. Maintenir le porte-électrode, la pince de masse, le câble de

soudage et la machine à souder en bon et sûr état defonc­tionnement.

d.Ne jamais plonger le porte-électrode dans l’eau pour le

refroidir.

e. Ne jamais toucher simultanément les parties sous tension

des porte-électrodes connectés à deux machines à souder
parce que la tension entre les deux pinces peut être le total
de la tension à vide des deux machines.

f. Si on utilise la machine à souder comme une source de

courant pour soudage semi-automatique, ces precautions
pour le porte-électrode s’applicuent aussi au pistolet de
soudage.

2. Dans le cas de travail au dessus du niveau du sol, se protéger
contre les chutes dans le cas ou on recoit un choc. Ne jamais
enrouler le câble-électrode autour de n’importe quelle partie du
corps.

3. Un coup d’arc peut être plus sévère qu’un coup de soliel, donc:

a. Utiliser un bon masque avec un verre filtrant approprié ainsi

qu’un verre blanc afin de se protéger les yeux du rayon­nement de l’arc et des projections quand on soude ou
quand on regarde l’arc.

b. Porter des vêtements convenables afin de protéger la peau

de soudeur et des aides contre le rayonnement de l‘arc.

c. Protéger l’autre personnel travaillant à proximité au

soudage à l’aide d’écrans appropriés et non-inflammables.

4. Des gouttes de laitier en fusion sont émises de l’arc de
soudage. Se protéger avec des vêtements de protection libres
de l’huile, tels que les gants en cuir, chemise épaisse, pan­talons sans revers, et chaussures montantes.

5. Toujours porter des lunettes de sécurité dans la zone de
soudage. Utiliser des lunettes avec écrans lateraux dans les
zones où l’on pique le laitier.

6. Eloigner les matériaux inflammables ou les recouvrir afin de
prévenir tout risque d’incendie dû aux étincelles.

7. Quand on ne soude pas, poser la pince à une endroit isolé de
la masse. Un court-circuit accidental peut provoquer un
échauffement et un risque d’incendie.

8. S’assurer que la masse est connectée le plus prés possible de
la zone de travail qu’il est pratique de le faire. Si on place la
masse sur la charpente de la construction ou d’autres endroits
éloignés de la zone de travail, on augmente le risque de voir
passer le courant de soudage par les chaines de levage,
câbles de grue, ou autres circuits. Cela peut provoquer des
risques d’incendie ou d’echauffement des chaines et des
câbles jusqu’à ce qu’ils se rompent.

9. Assurer une ventilation suffisante dans la zone de soudage.
Ceci est particuliérement important pour le soudage de tôles
galvanisées plombées, ou cadmiées ou tout autre métal qui
produit des fumeés toxiques.

10. Ne pas souder en présence de vapeurs de chlore provenant
d’opérations de dégraissage, nettoyage ou pistolage. La
chaleur ou les rayons de l’arc peuvent réagir avec les vapeurs
du solvant pour produire du phosgéne (gas fortement toxique)
ou autres produits irritants.

11. Pour obtenir de plus amples renseignements sur la sûreté, voir
le code “Code for safety in welding and cutting” CSA Standard
W 117.2-1974.

PRÉCAUTIONS DE SÛRETÉ POUR
LES MACHINES À SOUDER À
TRANSFORMATEUR ET À
REDRESSEUR

1. Relier à la terre le chassis du poste conformement au code de
l’électricité et aux recommendations du fabricant. Le dispositif
de montage ou la piece à souder doit être branché à une
bonne mise à la terre.

2. Autant que possible, I’installation et l’entretien du poste seront
effectués par un électricien qualifié.

3. Avant de faires des travaux à l’interieur de poste, la debranch­er à l’interrupteur à la boite de fusibles.

4. Garder tous les couvercles et dispositifs de sûreté à leur place.

MASTER TABLE OF CONTENTS FOR ALL SECTIONS

iv iv

PRO-CUT 25

Page

Safety .................................................................................................................................................i-iii

Installation .............................................................................................................................Section A

Technical Specifications .............................................................................................................A-2

Safety Precautions......................................................................................................................A-3

Select Proper Location ...............................................................................................................A-3

Stacking ......................................................................................................................................A-3

Tilting...........................................................................................................................................A-3

High Frequency Interference Protection.....................................................................................A-3

Input Electrical Connections.......................................................................................................A-3

Gas Input Connections ...............................................................................................................A-4

Output Connections....................................................................................................................A-5

Torch.....................................................................................................................................A-5

Operation...............................................................................................................................Section B

Safety Precautions ....................................................................................................................B-2

Description ................................................................................................................................B-2

Preheating Temperature .............................................................................................................B-2

User Responsibilities .................................................................................................................B-3

Operational Features and Controls ............................................................................................B-3

Design Features and Advantages ..............................................................................................B-3

Cutting Capability .......................................................................................................................B-4

Consumable Life.........................................................................................................................B-4

Limitations ..................................................................................................................................B-5

Controls and Settings.................................................................................................................B-5

Pilot Arc Discussion....................................................................................................................B-6

Procedure Recommendations....................................................................................................B-7

General.................................................................................................................................B-7

Suggestions For Extra Utility From The Pro-Cut System....................................................B-7

Accessories ..........................................................................................................................Section C

Maintenance .........................................................................................................................Section D

Theory of Operation .............................................................................................................Section E

Troubleshooting and Repair.................................................................................................Section F

How to Use Troubleshooting Guide............................................................................................F-2

Troubleshooting Guide ................................................................................................................F-4

Test Procedures ..........................................................................................................................F-9

Replacement Procedures .........................................................................................................F-29

Electrical Diagrams..............................................................................................................Section G

Parts Manual (Pro Cut 25)...............................................................................................P-357 Series

Cutting Torch ...................................................................................................P-210-U

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PRO-CUT 25

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NOTES

TABLE OF CONTENTS

- INSTALLATION SECTION -

Section A-1 Section A-1

PRO-CUT 25

Installation

Technical Specifications .............................................................................................................A-2

Safety Precautions......................................................................................................................A-3

Select Proper Location...............................................................................................................A-3

Stacking......................................................................................................................................A-3

Tilting ..........................................................................................................................................A-3

High Frequency Interference Protection.....................................................................................A-3

Input Electrical Connections.......................................................................................................A-3

Gas Input Connections...............................................................................................................A-4

Output Connections ...................................................................................................................A-5

Torch.....................................................................................................................................A-5

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INSTALLATION

A-2 A-2

PRO-CUT 25

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W

eight

Including

Torch Cable

35 lbs.

15.9 kg.

INPUT - SINGLE PHASE / 60 HERTZ ONLY

RATED OUTPUT

OUTPUT

RECOMMEND INPUT WIRE AND FUSE SIZES

REQUIRED GAS FLOW RATE REQUIRED GAS INLET PRESSURE

PHYSICAL DIMENSIONS

TECHNICAL SPECIFICATIONS - PRO-CUT 25 (K1756-1)

Standard Voltage

Duty Cycle

20% on 115 V
60% on 115 V

100% on 230 V

35% on 115 V
60% on 230 V

Current

Range

12-25 Amps

AC Input

Voltage

at
50/60
Hertz

230V-1Ø

115V-1Ø
115V-1Ø
115V-1Ø

Fuse

(Super Lag)

Circuit Breaker

(Delay Type)

20 AMPS
15 AMPS

20 AMPS
30 AMPS

#14 (2.5 mm

2

)

#12 (4 mm

2

)

#12 (4 mm

2

)

#12 (4 mm

2

)

2 Input Supply Wires

1 Ground Wire

#14 (2.5 mm

2

)

#12 (4 mm

2

)

#12 (4 mm

2

)

#12 (4 mm

2

)

Type 75

o

C

Copper Wire in Conduit

AWG (IEC) Sizes

Depth

16.1 in.

410 mm

W

idth

6.3 in.

160 mm

Height

10.2 in.

260 mm

Open Circuit

V

oltage

400 VDC

For all plasma cutting applications

Based on U.S. National Electrical Code

Ambient Temperature 30

o

C or Less

Pilot Current

12 Amps

AMPS

15 A
20 A
20 A
25 A
25 A

1Ø Input Current at Rated Output

115/230/1/50/60Hz 115 V : 15 A @ 20%

115 V : 26.7A@ 60%
115 V : 37.7A@ 35%
230 V : 15 A@100%
230 V : 19 A@ 60%

55 PSI @ 240 SCFH

( 3.8 Bar. @ 6800 LHR)

65 to 150 PSI

(4.5 Bar. TO 10.3 Bar.)

25 A
15 A

20 A
25 A

Output

Input Cord

Plug
Size

6-20P or 6-30P or 6-50P

5-15P* or 5-20P* or 5-30P or 5-50P

5-20P* or 5-30P or 5-50P

5-30P or 5-50P

* Included with machine

INSTALLATION

A-3 A-3

PRO-CUT 25

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Read entire Installation Section before installing the
PRO-CUT 25.

SAFETY PRECAUTIONS

ELECTRIC SHOCK CAN KILL.

• Only qualified personnel
should install this machine.

•Turn the input power OFF
at the disconnect switch or
fuse box and discharge input
capacitors before working
inside the equipment.

• Do not touch electrically hot parts.

•Turn the PRO-CUT Power Switch OFF
when connecting power cord to input
power.

___________________________________________

SELECT PROPER LOCATION

Place the PRO-CUT 25 where clean cool air can freely
circulate in and out the side louvers. Dirt, dust or any
foreign material that can be drawn into the machine
should be kept at a minimum. Failure to observe these
precautions can result in excessive operating temper­atures and nuisance shutdown of the machine.

A source of clean, dry air or nitrogen must be supplied
to the PRO-CUT 25. Oil in the air is a severe problem
and must be avoided. The supply pressure must be
between 80 and 150 psi. The flow rate is approximate­ly 4.0 cfm (113 l/min.). Failure to observe these pre­cautions could result in excessive operating tempera­tures or damage to the torch.

STACKING

The PRO-CUT 25 cannot be stacked.

TILTING

The PRO-CUT 25 must be placed on a stable, level
surface so it will not topple over.

HIGH FREQUENCY INTERFERENCE
PROTECTION

The PRO-CUT 25 employs a touch start mechanism
for arc initiation which eliminates high frequency emis­sions from the machine as compared with spark gap
and solid state type high frequency generators. Keep
in mind, though, that these machines may be used in
an environment where other high frequency generating
machines are operating. By taking the following steps,
high frequency interference into the Pro-Cut can be
minimized

(1) Make sure the power supply chassis is connected

to a good earth ground. The work terminal ground
does NOT ground the machine frame.

(2) Keep the work clamp isolated from other work

clamps that have high frequency.

(3) If the work clamp cannot be isolated, then keep the

clamp as far as possible from other work clamp
connections.

(4) When the machine is enclosed in a metal building,

several good earth driven electrical grounds
around the periphery of the building are recom­mended.

Failure to observe these recommended installation
procedures may cause improper function of the Pro­Cut or possibly even damage to the control system or
power supply components.

INPUT ELECTRICAL CONNECTIONS

The PRO-CUT 25 is rated for 115VAC or 230VAC
inputs and will automatically reconnect for the supplied
voltage. The machine is shipped from the factory for
operation on 115VAC 15 amp circuits. Use on 15 amp
branch circuits will limit cutting output as indicated by
the graphics around the output knob. If the output is set
at 20 amps or greater, the input fuse or circuit breaker
may “blow” in roughly 30 seconds or less (depending
on fuse or circuit breaker type).

To achieve 20 amp output with 115VAC input, replace
the 15 amp plug on the input cord with the supplied 20
amp plug, and connect the unit to a 20 amp branch cir­cuit with super lag fuses (or equivalent breaker). To
install the supplied 20 amp plug: Connect the white
(neutral) wire under terminal clamp with silver screw,
and black (hot) wire under terminal clamp with brass
screw. Connect green wire under terminal clamp with
green screw. Tighten terminal wire clamp screws
securely.

WARNING

INSTALLATION

A-4 A-4

PRO-CUT 25

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• Failure to wire as instructed may cause personal
injury or damage to equipment.

• To be installed or checked by an electrician or
qualified person only.

-----------------------------------------------------------------------­Use of normal 20 amp household breakers may result
in over current trips. If breaker trips occur, reduce the
cutting current output until nuisance trips stop.

To achieve the full 25 amp output capability of the
machine with 115 VAC input, remove the 15 amp or 20
amp plug on the input cord and install a 30 amp or 50
amp plug designed for 115 VAC (NEMAstyle 5-30P or
5-50P). Follow the instructions included with the plug.
Connect to an appropriate branch circuit with a mating
receptacle.

The PRO-CUT 25 performs best when connected to
230VAC inputs. To change over to 230VAC operation,
install a 230VAC plug with a current rating equal to or
greater than 20 amps.

For use on engine drives, keep in mind the above input
draw restrictions and the following precaution.

The PRO-CUT 25 can be operated on engine driven
generators as long as the 230 volt auxiliary meets the
following conditions:

• The AC waveform peak voltage is below 400 volts*.

• The AC waveform frequency is between 45 and 65
Hz.

• The RMS voltage of the AC waveform is always
greater than 208VAC *.

*

for 115 VAC input divide these values in half

The following Lincoln engine drives meet these condi­tions when run in the high idle mode:

Ranger 200 & 250 engine drives
Commander 300, 400, & 500 engine drives

Some engine drives do not meet these conditions (eg
Miller Bobcats, etc). Operation of the PRO-CUT 25 is
not recommended on engine drives not conforming to
these conditions. Such combinations may overvoltage
the PRO-CUT 25 power source.

GAS INPUT CONNECTIONS

Supply the PRO-CUT 25 with clean compressed air or
nitrogen.

• Supply pressure must be between 80 psi
and 150 psi.

• Flow rate should be approximately 4.0
cfm (113 I/min.).

NOTE: Oil in the air supply to the PRO-CUT 25 can

cause severe problems. Use only a clean air
supply.

•

Compressed gas can be supplied either through the air
fitting supplied with the machine or through the

1

/4-19

BSPP

thread at the rear of the machine. To use the air
fitting supplied with the machine (packaged in the con­sumable kit), apply teflon tape to the fitting threads and
install the fitting in the port at the rear of the machine.

• If compressed air is being used, it is highly recom­mended that an inline filter be installed in the air sup­ply line ahead of the air connection to the PRO-CUT

25.

• A standard nominal 5 micron inline filter is recom­mended; however, for optimum performance,select a
prefilter with a 3 micron absolute rating. If these filter
ratings are unavailable, anything with a rating less
than, or equal to, 20 micron would be acceptable to
use. In line filter elements will generally filter the air
with little restriction to the airflow until the element is
about 75% contaminated. After this point, there will
be a noticeable pressure drop in the line. Filter ele­ments should be replaced when a pressure drop of 8­10 psi is indicated; however, for optimum perfor­mance of the PRO-CUT 25, the filter element should
be replaced at or before the pressure drop reaches 8
psi. Be sure to select a filter that will accommodate
the necessary flow rating for the PRO-CUT 25 as
specified in the Installation section of this instruction
manual under the Gas Input Connections heading.

WARNING

INSTALLATION

A-5 A-5

PRO-CUT 25

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NOTE: When using nitrogen gas from a cylinder, the

cylinder must have a pressure regulator.

• Maximum psi from a nitrogen gas cylinder to
the PRO-CUT 25 regulator should never
exceed 150 psi.

• Install a hose between the nitrogen gas
cylinder regulator and the PRO-CUT 25
gas inlet

.

CYLINDER could explode if dam­aged.

• Keep cylinder upright and chained
to a fixed support.

• Keep cylinder away from areas where it could be
damaged.

• Never lift machine with cylinder attached.

• Never allow the cutting torch to touch the cylinder.

• Keep cylinder away from live electrical parts.

• Maximum inlet pressure 150 psi.

__________________

OUTPUT CONNECTIONS

Torch

The PRO-CUT 25 is sent from the factory with a 15’
PCT 20 cutting torch installed. Additional cutting torch­es can be ordered from the K1615 series. Hand-held
torches come with 15' or 25’ cables.

WARNING

NOTES

A-6 A-6

PRO-CUT 25

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Section B-1 Section B-1

PRO-CUT 25

TABLE OF CONTENTS

- OPERATION SECTION -

Operation...............................................................................................................................Section B

Safety Precautions......................................................................................................................B-2

Description .................................................................................................................................B-2

Preheating Temperature .............................................................................................................B-2

User Responsibility ....................................................................................................................B-3

Operational Features and Controls ............................................................................................B-3

Design Features and Advantages...............................................................................................B-3

Cutting Capability .......................................................................................................................B-4

Consumable Life.........................................................................................................................B-4

Limitations...................................................................................................................................B-5

Controls and Settings.................................................................................................................B-5

Pilot Arc Discussion ...................................................................................................................B-6

Procedure Recommendations....................................................................................................B-7

General .................................................................................................................................B-7

Suggestions for Extra Utility From the Pro-Cut System......................................................B-7

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B-2

B-2

PRO-CUT 25

OPERATION

Read and understand this entire section before operat­ing the machine.

SAFETY PRECAUTIONS

DESCRIPTION

The PRO-CUT 25 is a constant current, continuous
control plasma cutting power source. It provides supe­rior and reliable starting characteristics, cutting visibili­ty and arc stability. The control system has a safety
mechanism to insure that the nozzle and electrode are
in place before cutting or gouging. This is extremely
important due to the high voltages involved.

The PRO-CUT 25 comes standard with an air regula­tor and pressure gauge. The machine also comes with
an input power cord. Hand-held torches are available
in 15' or 25' cable. Consumables are included with
each Pro-Cut purchase so that cutting can begin right
out of the box. Consumables can also be ordered as
individual packages.

The PRO-CUT 25 initiates the plasma arc with a sim­ple, yet reliable, touch start mechanism. This system
eliminates many of the failure problems associated
with hi-frequency start systems.

PREHEAT TEMPERATURE FOR
PLASMA CUTTING

Preheat temperature control is not necessary in most
applications when plasma arc cutting or gouging.
Preheat temperature control may be necessary on high
carbon alloy steels and heat treated aluminum for crack
resistance and hardness control. Job conditions, pre­vailing codes, alloy level, and other considerations may
also require preheat temperature control. The following
minimum preheat temperature is recommended as a
starting point. Higher temperatures may be used as
required by the job conditions and/or prevailing codes. If
cracking or excessive hardness occurs on the cut face,
higher preheat temperature may be required. The rec­ommended minimum preheat temperature for plate
thickness up to 1/2" (12.7mm) is 70°F (21.1°C).

ELECTRIC SHOCK
can kill.

• Do not touch electrically live parts
or electrode with skin or wet
clothing.

• Insulate yourself from work and
ground.

• Always wear dry insulating
gloves.

FUMES AND GASES
can be dangerous.

• Keep your head out of fumes.

• Use ventilation or exhaust to
remove fumes from breathing
zone.

WELDING, CUTTING and
GOUGING SPARKS
can cause fire or explosion

• Keep flammable material away.

• Do not weld, cut or gouge on

containers that have held combustibles.

Observe additional Safety Guidelines detailed in
the beginning of this manual.

WARNING

ARC RAYS
can burn.

•Wear eye, ear and body

protection.

PLASMA ARC
can injure

• Keep your body away from nozzle

and plasma arc.

• Operate the pilot arc with caution. The

pilot arc is capable of burning the
operator, others or even piercing
safety clothing.

OPERATION

B-3 B-3

PRO-CUT 25

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USER RESPONSIBILITY

Because design, fabrication, erection and cutting vari­ables affect the results obtained in applying this type of
information, the serviceability of a product or structure
is the responsibility of the user. Variation such as plate
chemistry, plate surface condition (oil, scale), plate
thickness, preheat, quench, gas type, gas flowrate
and equipment may produce results different than
those expected. Some adjustments to procedures may
be necessary to compensate for unique individual con­ditions. Test all procedures duplicating actual field con­ditions.

OPERATIONAL FEA TURES AND
CONTROLS

The PRO-CUT 25 comes with an ON/OFF POWER
SWITCH, OUTPUT CURRENT CONTROL, and
PURGE BUTTON.

DESIGN FEATURES AND
ADVANTAGES

The PRO-CUT 25 design makes plasma cutting
uncomplicated. This list of design features and advan­tages will help you understand the machine's total
capabilities so that you can get maximum use from
your machine.

- Light weight and portable design for industrial use.

- Continuous control, 12 - 25 amps.

- Reliable touch start mechanism for plasma arc initia­tion.

- Rapid arc restrike for fast cutting of expanded metal.

- Input over voltage protection.

- Bright 3.0 second timed pilot arc.

- Purge momentary push button.

- Air regulator and pressure gage included.

- Parts-in-Place mechanism to detect proper installa­tion of consumables and torch.

- Latching Parts-in-Place mechanism. Requires the
operator to turn the machine off and then on to reset.

- Preflow/Postflow timing. Preflow is eliminated if arc
is re-initiated in Postflow.

- Thermostatic Protection.

- Solid state over-current protection.

- Automatic reconnect for 115 VAC or 230 VAC inputs.

- Dead front display for machine status.

- Unique electrode and Vortech™ nozzle design for
optimum cooling and long life.

- Swirl texture inside Vortech™ nozzle for better start­ing reliability and higher quality cuts.

OPERATION

B-4 B-4

PRO-CUT 25

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CUTTING CAPABILITY

The PRO-CUT 25 is rated at 25 amps, at 35% duty cycle on a 10 minute basis. If the duty cycle is exceeded, a
thermal protector will shut off the output of the machine until it cools to the normal operating temperature.

Figure B.1 shows the cut capacity of the PRO-CUT 25 when cutting mild steel. (The graph plots cut thickness vs.
torch travel speed with a torch standoff of 0.15".)

Lincoln's PRO-CUT 25

Cut Capacity Chart

Recommended Torch T ra vel Speed (IPM)

80% of Maximum Speed

80

60

40

20

0

0.3750.125

0.250

Metal Thickness (Inches)

Figure B.1

CONSUMABLE LIFE

The expected life for the PRO-CUT 25's electrode under normal operating conditions is approximately 1000
starts/cuts. An erosion of .060" is typical for end of electrode life, however, the electrode life may last longer. A
green and erratic arc will indicate definite electrode failure and the electrode should be replaced immediately.

It is recommended that consumables be replaced in complete sets. (Example: Electrode and Nozzle). This will
maximize the performance of the PRO-CUT 25 system.

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OPERATION

B-5 B-5

PRO-CUT 25

LIMITATIONS

Do not exceed output current and duty cycle rating of
machine. Do not use the PRO-CUT 25 for pipe thaw­ing.

CONTROLS AND SETTINGS

When preparing to cut, position the machine as close
to the work as possible. Make sure you have all mate­rials needed to complete the job and have taken all
safety precautions. It is important to follow these oper­ating steps each time you use the machine.

• Turn the machine's ON/OFF POWER SWITCH to
OFF position.

• Connect the air supply to the machine.

• Turn the main power and the machine power switch
on.

- The fan should start.

- The pre-charge circuit will operate for 3 seconds,
then the green "Power" LED should turn on.

• Be sure that the work lead is clamped to the work­piece before cutting.

• Set the output current control knob at maximum

1

position for higher cutting speed and less dross for­mation. Reduce the current, if desired to reduce the
kerf (cut) width, heat affected zone or travel speed
as required.

1

Maximum output requires a 30 amp input circuit and breaker. Refer to the
Technical Specifications for proper input circuit guidelines.

PRESSURE REGULATOR
CAP

• Push-in and hold the Purge button to check or set
the gas pressure. Pull the pressure regulator cap out
and turn it to set the pressure.

- Adjust the gas regulator for 65 PSI for 15’ or 25’
torches.

- Release the Purge button.

- The gas will immediately turn off. The pressure
gage may show an increase in pressure after the
air turns off but this is normal. Do NOT reset the
pressure while the air is NOT flowing.

• When ready to cut, place the torch near the work,
make certain all safety precautions have been taken
and pull the trigger.

- The air will flow for a preflow time of 2 seconds
and the pilot arc will start. (Exceptions: the first
time that the trigger is pulled after the machine is
turned on, or after a thermal tripout, will be
ignored. This is a safety feature to prevent the
pilot arc from firing unexpectedly or if the torch
button is pressed because it is laying up against
something. The other exception is if the machine
is in postflow, then the preflow time is skipped
and the pilot arc will start immediately.)

- The pilot arc will run for 3.0 seconds and shut off
unless the arc is brought in contact with the work
and the arc is transferred. Avoid excessive pilot
arc time by transferring the arc to the workpiece
quickly.

- When the arc is brought within 1/8” - 1/4" from
the work piece: the arc will transfer, the current
will ramp to the setting on the control panel, and
the cut can last indefinitely (or until the duty
cycle of the Pro-Cut is exceeded).

• Pierce the work piece by slowly lowering the torch
onto the metal at a 30

0

angle away from the operator.
This will blow the dross away from the torch tip.
Slowly rotate the torch to vertical position as the arc
becomes deeper.

• Keep moving while cutting. Cut at a steady speed
without pausing. Maintain the cutting speed so that
the arc leg is 10° to 20° behind the travel direction.

30

30

0

0

VER

VER

TICAL ANGLE

TICAL ANGLE

FOR CUTTING

FOR CUTTING

CUT

90

0

TORCH AT 300ANGLE

TO PIERCE

ROTATE TO

90

0

ANGLE TO CUT

OPERATION

B-6 B-6

PRO-CUT 25

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Direction of Travel

5° - 15°

10° - 20°

Arc Lag

Leading Angle

•

Use a 5° - 15° leading angle in the direction of the cut.

• Finish the cut to be made and release the trigger.

• When the trigger is released, the arc will stop.

- The gas will continue to flow for 10 seconds of
postflow. If the trigger is activated within this time
period, the pilot arc will immediately restart.

• If the dross is difficult to remove, reduce the cutting
speed. High speed dross is more difficult to remove
than low speed dross.

• The right side of the cut is more square than the left
as viewed along the direction of travel.

• Clean spatter and scale from the nozzle frequently.

• If the "SAFETY" LED lights at any time; check the

following:

• Check the assembly of the torch consumables. If
they are not properly in place, the machine will not
start. Make sure that the shield cup is hand

tight. Do not use pliers or over tighten.

• Check the conditions of the inside of the nozzle. If
debris has collected, rub the electrode on the
inside bottom of the nozzle to remove any oxide
layer that may have built up. Refer to
"Suggestions for Extra Utility from the PRO-CUT
system".

• Check the condition of the electrode. If the end
has a crater-like appearance, replace it along with
the nozzle. The maximum wear depth of the elec­trode is approximately .062”. A green and erratic
arc will indicate definite electrode failure and the
electrode should be replaced immediately.

• Replace the nozzle when the orifice exit is eroded
away or oval shaped.

• After the problem is found, or if there is nothing
apparently wrong, reset the machine by turning the
power switch OFF and then ON again. (It is possi­ble for electrical noise to trip the safety circuit on rare
occasions. This should not be a regular occurrence.)

• If the machine does not reset or continues to trip,

consult the Troubleshooting Section.

• Use the proper cutting procedures referred to in

Procedure Recommendations.

PILOT ARC DISCUSSION

The PRO-CUT has a smooth, continuous pilot arc.
The pilot arc is only a means of transferring the arc to
the workpiece for cutting. Repeated pilot arc starts, in
rapid succession, is not recommended as these starts
will generally reduce consumable life. Occasionally,
the pilot arc may sputter or start intermittently. This is
aggravated when the consumables are worn or the air
pressure is too high. Always keep in mind that the pilot
arc is designed to transfer the arc to the workpiece and
not for numerous starts without cutting.

When the pilot arc is started, a slight impulse will be felt
in the torch handle. This occurrence is normal and is
the mechanism which starts the plasma arc. This
impulse can also be used to help troubleshoot a "no
start" condition.

ELECTRIC SHOCK CAN KILL.

• Turn off machine at the disconnect
switch on the front of the machine
before tightening, cleaning or replacing
consumables.

----------------------------------------------------------------------------

WARNING

OPERATION

B-7 B-7

PRO-CUT 25

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PROCEDURE RECOMMENDATIONS

When properly used, plasma arc cutting is a very eco­nomical process. Improper use will result in a very high
operating cost.

General - In All Cases

• Follow safety precautions as printed throughout
this operating manual and on the machine.

• If piercing is required, slowly lower the torch at

an angle of about 30° to blow the dross away
from the torch tip and slowly rotate the torch to
a vertical position as the arc becomes deeper.
This process will blow a lot of molten metal and
dross. Be careful! Blow the dross away from
the torch, the operator and any flammable
objects.

• The nozzle may be dragged on the metal sur-

face, touching it lightly to the surface. NOTE:

The use of a drag cup with the PRO-CUT is
not recommended. The increased standoff
distance reduces the overall performance of
the PRO-CUT.

• Where possible, start the cut from the edge of

the work piece.

• Keep moving! Asteady speed is necessary . Do

not pause.

Suggestions for Extra Utility from the

PRO-CUT System:

1. Occasionally an oxide layer may form over the tip of
the electrode, creating an insulating barrier
between the electrode and nozzle. This will result in
the tripping of the Pro-Cut's safety circuit. When
this happens turn the power off, remove the nozzle
and electrode and use the electrode to rub against
the inside bottom surface of the nozzle. This will
help remove any oxide buildup. Replace the noz­zle, turn on the power and continue cutting. If the
safety circuit continues to trip after cleaning the
consumables, then replace them with a new set.
Do not continue to try and cut with excessively worn
consumables as this can cause damage to the
torch head and will degrade cut quality. Do not
allow torch cable or body to contact hot surface.

2. To improve consumable life, here are some sug­gestions that may be useful:

a. Make sure the air supply to the Pro-Cut is

clean and free of oil. Use several extra in line
filters if necessary.

b. Minimize dross buildup on the nozzle tip by

starting the cut from the edge of the plate when

possible.

c. Pierce cutting should be done only when nec-

essary. If piercing, angle torch about 30° from
the plane perpendicular to the work piece,
transfer the arc, then bring the torch perpen­dicular to the work and begin parallel move­ment.

d. Reduce the number of pilot arc starts without

transferring to the work.

e. Reduce the pilot arc time before transferring to

the work.

f. Set air pressure to recommended setting. A

higher or lower pressure will cause turbulence
in the plasma arc, eroding the orifice of the
nozzle tip.

g. Use only Lincoln consumable parts. These

parts are patented and using any other
replacement consumables may cause damage
to the torch or reduce cut quality.

Torch Standoff

DRAG thru 1/16"

Standoff

DRAG thru 1/16”

Standoff

ELECTRIC SHOCK CAN KILL.

• Turn off machine at the disconnect
switch on the front of the machine
before tightening, cleaning or replacing
consumables.

----------------------------------------------------------------------------

WARNING

NOTES

B-8 B-8

PRO-CUT 25

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TABLE OF CONTENTS

- ACCESSORIES -

Accessories...........................................................................................................................Section C

Options/Accessories...................................................................................................................C-2

Section C-1 Section C-1

PRO-CUT 25

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ACCESSORIES

C-2 C-2

PRO-CUT 25

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ALW

AYS USE GENUINE LINCOLN
ELECTRIC ELECTRODES AND
VORTECH™

NOZZLES

• Only Genuine Lincoln Electric consumables yield the

best cutting performance for the PRO-CUT 25.

• The patented VORTECH™ nozzle provides an

extra “kick” of swirl as the arc exits the nozzle which
improves cutting performance. No other nozzle has

this capability or can match its performance.

GENERAL OPTIONS /
ACCESSORIES

The following options/accessories are available for
your PRO-CUT 25 from your local Lincoln Distributor.

S22147-028 - VORTECH™ nozzle with an .028” (0.7
mm) Orifice

S22149 - Electrode - replacement electrodes for cut­ting.

S22150 - Shield Cup - This shields the nozzle and pro­vides more visibility to the workpiece. Note the shield
cup does not prevent the torch tip from touching the
workpiece.

K1615 Series - PCT 20 Torches come in 15’ and 25’
lengths. Refer to the Parts Pages in the rear of this
manual for Torch parts.

Section D-1 Section D-1

PRO-CUT 25

TABLE OF CONTENTS

-MAINTENANCE-

Maintenance .........................................................................................................................Section D

Routine Maintenance..................................................................................................................D-2

Periodic Maintenance .................................................................................................................D-2

Thermal Protection .....................................................................................................................D-2

Replacement Of Internal Fuse....................................................................................................D-2

Major Component Locations .....................................................................................................D-3

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MAINTENANCE

D-2 D-2

PRO-CUT 25

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PERIODIC MAINTENANCE

Change consumables as required.

THERMAL PROTECTION

Thermal Detection Devices protect the machine from
excessive operating temperatures. Excessive temper­atures may be caused by a lack of cooling air or oper­ating the machine beyond the duty cycle and output
rating. If excessive operating temperatures should
occur, the yellow thermal LED will light and the
Detection Devices will prevent output voltage or cur­rent.

These Detection Devices are self-resetting once the
machine cools sufficiently. If the thermostat shutdown
was caused by excessive output or duty cycle and the
fan is operating normally , the Power Switch may be left
on and the reset should occur within a 15 minute peri­od. If the fan is not turning or the air intake louvers
were obstructed, then the power must be switched off
and the fan problem or air obstruction must be correct­ed.

A protection circuit is included to monitor the voltage
across filter capacitors. In the event that the capacitor
voltage is too high, the protection circuit will prevent
output.

REPLACEMENT OF INTERNAL FUSES

The PRO-CUT 25 has additional protection provided to
some circuits through internal fuses. For replacement
of those fuses proceed as follows:

1. Turn off the power to the unit and remove the input
plug.

2. Allow the machine to stand for 5 minutes to let the
input capacitors discharge.

3. Remove the machine cover.

4. Replace the blown fuse with a new 0.5A 500V
slowblow fuse or 32A 400V fuse as appropriate.

NOTE: If the fuse blows again after power is restored,

the cause could be an internal breakdown in
the power unit. In this case, take the unit to an
authorized Lincoln Field Service Shop.

ELECTRIC SHOCK can kill.

• Have an electrician install and service
this equipment.

• Turn the input power off at the fuse box
before working on equipment.

• Do not touch electrically hot parts.

• Prior to Performing preventative main­tenance, perform the following capaci­tor discharge procedure to avoid elec­tric shock.

---------------------------------------------------------------------

ROUTINE MAINTENANCE

1. Keep the cutting or gouging area and the area
around the machine clean and free of combustible
materials. No debris should be allowed to collect
which could obstruct air flow to the machine.

2. Every 6 months or so, the machine should be
cleaned with a low pressure airstream. Keeping the
machine clean will result in cooler operation and
higher reliability. Be sure to clean these areas:

- Printed circuit boards and heat sinks

- Power switch

• When using a low pressure aistream, wear
appropiate eye protection.

------------------------------------------------------------------------

3. Examine the sheet metal case for dents or break­age. Repair the case as required. Keep the case in
good condition to insure that high voltage parts are
protected and correct spacings are maintained. All
external sheet metal screws must be in place to
insure case strength and electrical ground continu­ity.

4. Inspect the cable periodically for any slits or punc­ture marks in the cable jacket. Replace if neces­sary. Check to make sure that nothing is crushing
the cable and blocking the flow of air through the air
tube inside. Also, check for kinks in the cable peri­odically and relieve any so as not to restrict the flow
of air to the torch.

WARNING

ELECTRIC SHOCK CAN KILL.

• Turn off machine at the disconnect
switch on the front of the machine
before tightening, cleaning or replacing
consumables.

----------------------------------------------------------------------------

WARNING

CAUTION

L

IN

C

O

L

N

E

L

E

C

T

R

IC

PRO-CUT 25

O

N

O

F

F

P

U

R

G

E

POWER

GAS PRESSURE

THERMAL

SAFETY

!

R
E
Q

U
I
R
E
S

2
0
A

/
1
1
5

V
B
R
A
N

C
H
C

I
R
C
U
I
T

R
E
Q

U
I
R
E
S

3
0
A

/
1
1
5

V
B
R
A
N

C
H
C

I
R
C
U
I
T

2
5

2

0

P

C

T

2

0

6

1

2

4

3

5

7

MAINTENANCE

D-3 D-3

PRO-CUT 25

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FIGURE D.2 – MAJOR COMPONENT LOCATIONS

1. Central Metal Wall

2. Main Board

3. Input Board

4. Control Board

5. Fan

6. Case Wraparound

7. Torch

NOTES

D-4 D-4

PRO-CUT 25

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Section E-1 Section E-1

PRO-CUT 25

Theory of Operation .............................................................................................................Section E

General Description ....................................................................................................................E-2

Input Line Voltage and Auxiliary Transformer .............................................................................E-2

Precharge and Protection ...........................................................................................................E-3

Main Transformer ........................................................................................................................E-4

Output Section and Torch...........................................................................................................E-5

Control Board .............................................................................................................................E-6

Protection Circuits ......................................................................................................................E-7

Overload Protection..............................................................................................................E-7

Thermal Protection ...............................................................................................................E-7

Accidental Operation Protection.................................................................................................E-7

Safety Parts-In-Place Protection ................................................................................................E-7

Insulated Gate Bipolar Transistor (IGBT) Operation ...................................................................E-8

TABLE OF CONTENTS

-THEORY OF OPERATION SECTION-

115/230/1/50/60 VAC

INPUT

CN1

2

1

4

3

5
6
7
8

300uH

L1

RL3

10/10W

R1

V2

V1

B

A

1A/250V

F1

RL2

RL2

RL2

AC

CP

CP

AC

L1

RL1

RL2

115VAC

230V

T1

115V

RL1

L1

15VAC
15VAC
SAFETY
+28VDC
SEC GND
OVLOAD
115/230
+12VDC

AC

CP
CP

AC

CN2

6

9

10

2

20

15 16

+15Vrms

EV1

NO

COM

NC

12VDC

PS2

PS1

861793

OVLOAD

SEC GND

SAFETY

CN1

12 18 14 1 11 4 13 7 19 24 21 23 8 1 2 3

3

22

17

V+

+12VDC

+12VDC_SW

+8V_SW

SEC GND

OVLOAD

TRANSFER SW

TRANSFER

SOL 1 DRIVER

SOL 2 DRIVER

TRIGGER

OUTPUT

V_OUT

121814 7 15 4 11 5 16 10 12 13

5

4

POT_WIPER

23

POT_CW

22

POT_CCW

24

CP

15K/3W

R1

15K/3W

R2

1500uF/250V

C2a,b

1500uF/250V

C1a,b

C12

CP

C26

IRG4BC30W

Q1a,b,c

IRG4BC30W

Q2a,b,c

SEC

PRI

T2

C13

D10

D11

240uH

Lout

SHUNT

SH-

SH+

BS1

8A

+12VDC

TRANSFER

C14

6.8k/5W

R24

WRK

NZL (2)

EL (3)

CN3

2

1

3
4

12VDC

PT

WORK CLAMP

CN1

SW1

230VAC

FN1

+

+

RL1

Display LED's

Control Board

Output Control

Air

Solenoid

1

Purge

Switch

Input

Voltage Board

Main Inverter Board

Solenoid 2

FIGURE E.1 – PRO-CUT 25 BLOCK LOGIC DIAGRAM

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FIGURE E.2 – INPUT LINE VOLTAGE

GENERAL DESCRIPTION

The PRO-CUT 25 is an inverter based constant
current, continuous control plasma cutting power
source. The control system has a safety mechanism
to insure that the nozzle and electrode are in place
before cutting or gouging. The PRO-CUT 25 initiates
the plasma arc with a simple, yet reliable, touch start
mechanism. This system eliminates many of the prob­lems associated with hi-frequency type start systems.

INPUT LINE VOLTAGE, AND
AUXILIARY TRANSFORMER

The single-phase input power of 115 230 Volts AC is
connected to the machine, via an input cord, to a
switch located on the front panel.

The PRO-CUT 25 Input voltage board automatically
reconnects the auxiliary and inverter connections to
configure the machine for either a low 115V AC or high
230V AC input voltage. The auxiliary transformer
develops the appropriate AC voltages to operate the
cooling fan, the control board, and the inverter board.

THEORY OF OPERATION

E-2 E-2

PRO-CUT 25

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NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.

115/230/1/50/60 VAC

INPUT

CN1

2

1

4

3

5
6
7
8

300uH

L1

RL3

10/10W

R1

V2

V1

B

A

1A/250V

F1

RL2

RL2

RL2

AC

CP

CP

AC

L1

RL1

RL2

115VAC

230V

T1

115V

RL1

L1

15VAC
15VAC
SAFETY
+28VDC
SEC GND
OVLOAD
115/230
+12VDC

AC

CP
CP

AC

CN2

6

9
10

2
20

15 16

+15Vrms

EV1

NO

COM

NC

12VDC

PS2

PS1

861793

OVLOAD

SEC GND

SAFETY

CN1

12 18 14 1 11 4 13 7 19 24 21 23 8 1 2 3

3
22

17

V+

+12VDC

+12VDC_SW

+8V_SW

SEC GND

OVLOAD

TRANSFER SW

TRANSFER

SOL 1 DRIVER

SOL 2 DRIVER

TRIGGER

OUTPUT

V_OUT

121814 7 15 4 11 5 16 10 12 13

5

4

POT_WIPER

23

POT_CW

22

POT_CCW

24

CP

15K/3W

R1

15K/3W

R2

1500uF/250V

C2a,b

1500uF/250V

C1a,b

C12

CP

C26

IRG4BC30W

Q1a,b,c

IRG4BC30W

Q2a,b,c

SEC

PRI

T2

C13

D10

D11

240uH

Lout

SHUNT

SH-

SH+

BS1

8A

+12VDC

TRANSFER

C14

6.8k/5W

R24

WRK

NZL (2)

EL (3)

CN3

2

1

3
4

12VDC

PT

WORK CLAMP

CN1

SW1

230VAC

FN1

+

+

RL1

Display LED's

Control Board

Output Control

Air

Solenoid

1

Purge

Switch

Input

Voltage Board

Main Inverter Board

Solenoid 2

PRECHARGE AND PROTECTION

The input voltage is rectified by the input rectifier on
the inverter board. The resultant DC voltage is applied
to the filter capacitors through the automatic
reconnect of the input board. The input board also
contains precharging circuitry for the safe charging of
the input filter capacitors. Once the capacitors are
precharged the input board activates the RL3 input
relay. This connects full input power to the filter
capacitors. When the filter capacitors are fully
charged they act as power supplies for the IGBT
switching circuit. The IGBTs supply the main trans­former primary winding with DC current flow.

The inverter board also monitors the filter capacitors
for overvoltage. If this occurs, the appropriate signal
is sent to the control board to disable the machines
output and to turn on the Thermal/Voltage Overload
status LED. See IGBT Operation discussion and
diagrams in this section.

THEORY OF OPERATION

E-3 E-3

PRO-CUT 25

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NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.

115/230/1/50/60 VAC

INPUT

CN1

2

1

4

3

5
6
7
8

300uH

L1

RL3

10/10W

R1

V2

V1

B

A

1A/250V

F1

RL2

RL2

RL2

AC

CP

CP

AC

L1

RL1

RL2

115VAC

230V

T1

115V

RL1

L1

15VAC
15VAC
SAFETY
+28VDC
SEC GND
OVLOAD
115/230
+12VDC

AC

CP
CP

AC

CN2

6

9

10

2

20

15 16

+15Vrms

EV1

NO

COM

NC

12VDC

PS2

PS1

861793

OVLOAD

SEC GND

SAFETY

CN1

12 18 14 1 11 4 13 7 19 24 21 23 8 1 2 3

3

22

17

V+

+12VDC

+12VDC_SW

+8V_SW

SEC GND

OVLOAD

TRANSFER SW

TRANSFER

SOL 1 DRIVER

SOL 2 DRIVER

TRIGGER

OUTPUT

V_OUT

121814 7 15 4 11 5 16 10 12 13

5

4

POT_WIPER

23

POT_CW

22

POT_CCW

24

CP

15K/3W

R1

15K/3W

R2

1500uF/250V

C2a,b

1500uF/250V

C1a,b

C12

CP

C26

IRG4BC30W

Q1a,b,c

IRG4BC30W

Q2a,b,c

SEC

PRI

T2

C13

D10

D11

240uH

Lout

SHUNT

SH-

SH+

BS1

8A

+12VDC

TRANSFER

C14

6.8k/5W

R24

WRK

NZL (2)

EL (3)

CN3

2

1

3
4

12VDC

PT

WORK CLAMP

CN1

SW1

230VAC

FN1

+

+

RL1

Display LED's

Control Board

Output Control

Air

Solenoid

1

Purge

Switch

Input

Voltage Board

Main Inverter Board

Solenoid 2

FIGURE E.3 – PRECHARGE AND PROTECTION

THEORY OF OPERATION

E-4 E-4

PRO-CUT 25

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FIGURE E.4 – MAIN TRANSFORMER

115/230/1/50/60 VAC

INPUT

CN1

2

1

4

3

5
6
7
8

300uH

L1

RL3

10/10W

R1

V2

V1

B

A

1A/250V

F1

RL2

RL2

RL2

AC

CP

CP

AC

L1

RL1

RL2

115VAC

230V

T1

115V

RL1

L1

15VAC
15VAC
SAFETY
+28VDC
SEC GND
OVLOAD
115/230
+12VDC

AC

CP
CP

AC

CN2

6

9

10

2

20

15 16

+15Vrms

EV1

NO

COM

NC

12VDC

PS2

PS1

861793

OVLOAD

SEC GND

SAFETY

CN1

12 18 14 1 11 4 13 7 19 24 21 23 8 1 2 3

3

22

17

V+

+12VDC

+12VDC_SW

+8V_SW

SEC GND

OVLOAD

TRANSFER SW

TRANSFER

SOL 1 DRIVER

SOL 2 DRIVER

TRIGGER

OUTPUT

V_OUT

121814 7 15 4 11 5 16101213

5

4

POT_WIPER

23

POT_CW

22

POT_CCW

24

CP

15K/3W

R1

15K/3W

R2

1500uF/250V

C2a,b

1500uF/250V

C1a,b

C12

CP

C26

IRG4BC30W

Q1a,b,c

IRG4BC30W

Q2a,b,c

SEC

PRI

T2

C13

D10

D11

240uH

Lout

SHUNT

SH-

SH+

BS1

8A

+12VDC

TRANSFER

C14

6.8k/5W

R24

WRK

NZL (2)

EL (3)

CN3

2

1

3
4

12VDC

PT

WORK CLAMP

CN1

SW1

230VAC

FN1

+

+

RL1

Display LED's

Control Board

Output Control

Air

Solenoid

1

Purge

Switch

Input

Voltage Board

Main Inverter Board

Solenoid 2

MAIN TRANSFORMER

The pair of IGBTs act as a switch assembly. This
assembly feeds a primary winding of the main trans­former. When current is pulsed through this primary
winding, a resultant current is produced on the sec­ondary winding of the main transformer. The DC cur­rent flow through the primary winding is redirected or
“clamped” back to the filter capacitors when the IGBTs
are turned off. This is needed due to the inductance of
the transformer primary winding.

The primary current also passes through the current
transformer, which sends a signal to the control cir­cuits of the inverter board. This signal and the control
circuits limit the maximum primary current flow

through the IGBTs. The pair of IGBT’s are fired at 15
microsecond intervals, creating a constant 66.6KHz
output.

The secondary portion of the main transformer is made
up of one winding. This winding supplies the
electrode-to-nozzle and electrode-to-work voltages
and the resulting currents. This high current winding is
capable of supplying maximum output current during
the cutting process. The output current is regulated
via pulse width modulation. The control circuitry, on
the inverter board, receives a signal from the control
board and regulates the output current to the desired
level.

OUTPUT SECTION AND TORCH

The output section contains a relay which, upon
receiving a pilot signal from the control board will
enable the operation of a pilot arc or a cutting arc. The
printed circuit board mounted current sensor regulates
the pilot and cutting current. The output choke, which
is in series with both the pilot circuit and the cutting
circuit, provides current filtering to enhance arc stabil­ity.

The PCT 20 torch uses a patented touch start mecha­nism that provides superior starting performance over
other touch start systems. The torch head consists of
3 major parts: torch body, insulator and piston. The
insulator provides an electrical barrier between the
piston and torch body. The piston provides a path for
electrical current to the electrode. The piston also dri­ves the electrode to the nozzle for arc initiation. The
torch body contains the main torch components: the
trigger, pilot arc, cutting arc, and air flow systems are
included. See Figure F.10 & G Section for more detail.

A copper nozzle with a patented internal swirl is used
to focus the arc. A small, precise hole in the end of the
nozzle constricts the arc and increases the current
density. As the air enters the torch head, it is directed

between the electrode and nozzle for maximum elec­trode cooling. A portion of the cooling air exits in the
chamber through vents in the side of the nozzle. A
swirl texture located inside the bottom of the nozzle
increases the plenum air swirl strength, and improves
arc start reliability and parts-in-place verification.

Plasma arc initiation occurs as follows: First, in the idle
state, a spring inside the torch head pushes the piston
and electrode forward to make continuity with the noz­zle. When the trigger is pulled, air flow begins and cre­ates enough back force on the electrode to overcome
the force of the spring. However, the solenoid valve
allows enough forward force on the piston to maintain
continuity between the consumables. After this
continuity has been verified, output current is estab­lished and regulated. Once the current stabilizes, the
solenoid valve turns off, removing the forward force on
the piston. The back pressure drives the piston and
electrode away from the nozzle, creating the plasma
arc. The air stream forces the arc out the orifice of the
nozzle. This appears as a pilot arc, which can then be
transferred for cutting.

THEORY OF OPERATION

E-5 E-5

PRO-CUT 25

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FIGURE E.5 – PLASMA OUTPUT SECTION AND TORCH

115/230/1/50/60 VAC

INPUT

CN1

2

1

4

3

5
6
7
8

300uH

L1

RL3

10/10W

R1

V2

V1

B

A

1A/250V

F1

RL2

RL2

RL2

AC

CP

CP

AC

L1

RL1

RL2

115VAC

230V

T1

115V

RL1

L1

15VAC
15VAC
SAFETY
+28VDC
SEC GND
OVLOAD
115/230
+12VDC

AC

CP
CP

AC

CN2

6

9

10

2

20

15 16

+15Vrms

EV1

NO

COM

NC

12VDC

PS2

PS1

861793

OVLOAD

SEC GND

SAFETY

CN1

12 18 14 1 11 4 13 7 19 24 21 23 8 1 2 3

3

22

17

V+

+12VDC

+12VDC_SW

+8V_SW

SEC GND

OVLOAD

TRANSFER SW

TRANSFER

SOL 1 DRIVER

SOL 2 DRIVER

TRIGGER

OUTPUT

V_OUT

121814 7 15 4 11 5 16 10 12 13

5

4

POT_WIPER

23

POT_CW

22

POT_CCW

24

CP

15K/3W

R1

15K/3W

R2

1500uF/250V

C2a,b

1500uF/250V

C1a,b

C12

CP

C26

IRG4BC30W

Q1a,b,c

IRG4BC30W

Q2a,b,c

SEC

PRI

T2

C13

D10

D11

240uH

Lout

SHUNT

SH-

SH+

BS1

8A

+12VDC

TRANSFER

C14

6.8k/5W

R24

WRK

NZL (2)

EL (3)

CN3

2

1

3
4

12VDC

PT

WORK CLAMP

CN1

SW1

230VAC

FN1

+

+

RL1

Display LED's

Control Board

Output Control

Air

Solenoid

1

Purge

Switch

Input

Voltage Board

Main Inverter Board

Solenoid 2

CONTROL BOARD

The control board receives status and analog
feedback signals from the inverter board, input board,
and various sensors. The control circuitry interprets
these signals, makes decisions and changes the
machines mode and output to satisfy the requirements
as defined by the circuitry. The control board sends a
signal to the inverter board to control the output
current but the actual regulation circuits are on the
inverter board.

The display board, directly connected to the control
board, communicates PRO-CUT 25 status and
operating conditions to the user. There are four status
indicators: Power On, Gas Pressure, Thermal
Overload, and Safety Error.

THEORY OF OPERATION

E-6 E-6

PRO-CUT 25

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FIGURE E.6 – CONTROL BOARD

115/230/1/50/60 VAC

INPUT

CN1

2

1

4

3

5
6
7
8

300uH

L1

RL3

10/10W

R1

V2

V1

B

A

1A/250V

F1

RL2

RL2

RL2

AC

CP

CP

AC

L1

RL1

RL2

115VAC

230V

T1

115V

RL1

L1

15VAC
15VAC
SAFETY
+28VDC
SEC GND
OVLOAD
115/230
+12VDC

AC

CP
CP

AC

CN2

6

9

10

2

20

15 16

+15Vrms

EV1

NO

COM

NC

12VDC

PS2

PS1

861793

OVLOAD

SEC GND

SAFETY

CN1

12 18 14 1 11 4 13 7 19 24 21 23 8 1 2 3

3

22

17

V+

+12VDC

+12VDC_SW

+8V_SW

SEC GND

OVLOAD

TRANSFER SW

TRANSFER

SOL 1 DRIVER

SOL 2 DRIVER

TRIGGER

OUTPUT

V_OUT

121814 7 15 4 11 5 16 101213

5

4

POT_WIPER

23

POT_CW

22

POT_CCW

24

CP

15K/3W

R1

15K/3W

R2

1500uF/250V

C2a,b

1500uF/250V

C1a,b

C12

CP

C26

IRG4BC30W

Q1a,b,c

IRG4BC30W

Q2a,b,c

SEC

PRI

T2

C13

D10

D11

240uH

Lout

SHUNT

SH-

SH+

BS1

8A

+12VDC

TRANSFER

C14

6.8k/5W

R24

WRK

NZL (2)

EL (3)

CN3

2

1

3
4

12VDC

PT

WORK CLAMP

CN1

SW1

230VAC

FN1

+

+

RL1

Display LED's

Control Board

Output Control

Air

Solenoid

1

Purge

Switch

Input

Voltage Board

Main Inverter Board

Solenoid 2

PROTECTION CIRCUITS

Protection circuits are designed into the PRO-CUT 25
machine to sense trouble, damages, problems with
internal components, and to provide safety. These are
the main protection circuits:

OVERLOAD PROTECTION

The PRO-CUT 25 is electrically protected from
producing higher than normal output currents. If the
output current exceeds 25-30 amps, an electronic
protection circuit limits the current to within the
capabilities of the machine. A second circuit monitors
the input voltage and the voltage across the input filter
capacitors. If the input voltage or filter capacitor
voltage is too high, or too low, the protection circuit
will prevent machine output.

THERMAL PROTECTION

Three thermal protection devices protect the machine
from excessive operating temperatures. One device
is located on the output choke, one is located inside
the main transformer, and another is mounted on one
of the IGBT heat sinks. Excessive temperatures may
be caused by a lack of cooling air or by operating the
machine beyond the duty cycle and output rating. If
excessive operating temperatures should occur, the
thermal status indicator will turn on and the thermostat
will prevent output voltage or current. The thermal
protection devices are self-resetting once the machine
cools sufficiently. If the shutdown was caused by
excessive output or duty cycle and the fans are
operating normally, the power switch may be left on
and the reset should occur within a 15 minute period.
If the fan is not turning or the air intake louvers are
obstructed, the input power must be removed and the
fan problem or air obstruction must be corrected.
After a thermal overload occurs and the machine
resets, it may be necessary to activate the torch
trigger twice before a pilot arc will be initiated. This is
a safety precaution, to eliminate accidental pilot arc
initiation when the thermal protection self resets.

ACCIDENTAL OPERATION
PROTECTION

The PRO-CUT 25 has two protection circuits to
eliminate accidental pilot arc initiation. These two
circuits operate when the machine is first turned on
and after a thermal overload occurs. In these cases,
the first time the torch trigger is activated nothing will
happen. The torch trigger must be activated a second
time before pilot arc initiation occurs. This protection
is added in case the machine is turned on and the trig­ger is already activated or if a thermal overload self
resets and the trigger is activated.

SAFETY PARTS-IN-PLACE
PROTECTION

The PRO-CUT 25 has protection circuits to detect the
proper connection of the torch and the proper
installation of the consumables. If an error is detected
with either of these two items, the Safety status LED
will be turned on and the output of the machine will be
disabled. The PRO-CUT 25 must be turned off and
the problem must be corrected before normal
operation can occur.

THEORY OF OPERATION

E-7 E-7

PRO-CUT 25

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INSULATED GATE BIPOLAR
TRANSISTOR (IGBT) OPERATION

An IGBT is a type of transistor. IGBTs are semicon­ductors well suited for high frequency switching and
high current applications.

Drawing A shows an IGBT in a passive mode. There
is no gate signal, zero volts relative to the source, and
therefore, no current flow. The drain terminal of the
IGBT may be connected to a voltage supply; but since
there is no conduction the circuit will not supply
current to components connected to the source. The
circuit is turned off like a light switch in the OFF
position.

Drawing B shows the IGBT in an active mode. When
the gate signal, a positive DC voltage relative to the
source, is applied to the gate terminal of the IGBT, it
is capable of conducting current. A voltage supply
connected to the drain terminal will allow the IGBT to
conduct and supply current to circuit components
coupled to the source. Current will flow through the
conducting IGBT to downstream components as long
as the positive gate signal is present. This is similar
to turning ON a light switch.

THEORY OF OPERATION

E-8 E-8

PRO-CUT 25

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FIGURE E.5 – IGBT

DRAIN

SOURCE

GATE

INJECTING LAYER

BUFFER LAYER

DRAIN DRIFT REGION

BODY REGION

p +

n +

n -

p

n + n +

DRAIN

SOURCE

GATE

INJECTING LAYER

BUFFER LAYER

DRAIN DRIFT REGION

BODY REGION

p +

n +

n -

p

n + n +

POSITIVE
VOLTAGE
APPLIED

B. ACTIVE

A. PASSIVE

PRO-CUT 25

Section F-1 Section F-1

Troubleshooting & Repair Section .................................................................................Section F

How to Use Troubleshooting Guide ....................................................................................F-2

PC Board Troubleshooting Procedures and Replacement .................................................F-3

Troubleshooting Guide ........................................................................................................F-4

Test Procedures

Input Filter Capacitor Discharge Procedure .................................................................F-9

Main Inverter Board Resistance Test ............................................................................F-11

Input Board Voltage Test ...............................................................................................F-17

Main Inverter Board Voltage Test ..................................................................................F-21

To rch Continuity and Solenoid Test ..............................................................................F-25

Air/Gas Solenoid Test....................................................................................................F-29

Replacement Procedures

Control Board Removal and Replacement ...................................................................F-31

Input Board Removal and Replacement.......................................................................F-35

Main Inverter Board Removal and Replacement..........................................................F-39

Switch Removal and Replacement ...............................................................................F-43

Fan Removal and Replacement....................................................................................F-45

Retest after Repair ........................................................................................................F-48

TABLE OF CONTENTS

TROUBLESHOOTING & REPAIR SECTION

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PRO-CUT 25

HOW TO USE TROUBLESHOOTING GUIDE

Service and repair should be performed by only Lincoln Electric Factory Trained Personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician and machine
operator and will invalidate your factory warranty. For your safety and to avoid Electrical Shock, please
observe all safety notes and precautions detailed throughout this manual.

TROUBLESHOOTING & REPAIR

F-2 F-2

CAUTION

CAUTION

This Troubleshooting Guide is provided to help
you locate and repair possible machine
malfunctions. Simply follow the three-step
procedure listed below.

Step 1. LOCATE PROBLEM (SYMPTOM). Look
under the column labeled “PROBLEM
(SYMPTOMS)”. This column describes possible
symptoms that the machine may exhibit. Find
the listing that best describes the symptom that
the machine is exhibiting. Symptoms are
grouped into three main categories: Output
Problems, Function Problems, and LED Function
Problems.

Step 2. PERFORM EXTERNAL TESTS. The
second column, labeled “POSSIBLE AREAS OF
MISADJUSTMENT(S)”, lists the obvious external
possibilities that may contribute to the machine
symptom. Perform these tests/checks in the
order listed. In general, these tests can be
conducted without removing the case
wrap-around cover.

Step 3. PERFORM COMPONENT TESTS. The
last column, labeled “Recommended Course of
Action” lists the most likely components that may
have failed in your machine. It also specifies the
appropriate test procedure to verify that the
subject component is either good or bad. If there
are a number of possible components, check the
components in the order listed to eliminate one
possibility at a time until you locate the cause of
your problem.

All of the referenced test procedures referred to in
the Troubleshooting Guide are described in detail
at the end of this chapter. Refer to the
Troubleshooting and Repair Table of Contents to
locate each specific Test Procedure. All of the
referred to test points, components, terminal
strips, etc., can be found on the referenced
electrical wiring diagrams and schematics. Refer
to the Electrical Diagrams Section Table of
Contents to locate the appropriate diagram.

If for any reason you do not understand the test procedures or are unable to perform the test/repairs
safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before
you proceed. Call 1-888-935-3877

PRO-CUT 25

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ELECTRIC SHOCK can kill.

Have an electrician install and service
this equipment. Turn the machine OFF
before working on equipment. Do not
touch electrically hot parts.

Sometimes machine failures appear to be due to PC
board failures. These problems can sometimes be
traced to poor electrical connections. To avoid prob­lems when troubleshooting and replacing PC boards,
please use the following procedure:

1. Determine to the best of your technical ability that
the PC board is the most likely component caus­ing the failure symptom.

2. Check for loose connections at the PC board to
assure that the PC board is properly connected.

3. If the problem persists, replace the suspect PC
board using standard practices to avoid static
electrical damage and electrical shock. Read the
warning inside the static resistant bag and perform
the following procedures:

PC Board can be damaged by
static electricity.

• Remove your body’s static
charge before opening the static­shielding bag. Wear an anti-sta­tic wrist strap. For safety, use a
1 Meg ohm resistive cord con­nected to a grounded part of the
equipment frame.

• If you don’t have a wrist strap,
touch an unpainted, grounded,
part of the equipment frame.
Keep touching the frame to
prevent static build-up. Be sure
not to touch any electrically live
parts at the same time.

• Tools which come in contact with the PC Board must
be either conductive, anti-static or static-dissipative.

• Remove the PC Board from the static-shielding bag
and place it directly into the equipment. Don’t set
the PC Board on or near paper, plastic or cloth which
could have a static charge. If the PC Board can’t be
installed immediately, put it back in the static­shielding bag.

• If the PC Board uses protective shorting jumpers,
don’t remove them until installation is complete.

• If you return a PC Board to The Lincoln Electric
Company for credit, it must be in the static-shielding
bag. This will prevent further damage and allow
proper failure analysis.

4. Test the machine to determine if the failure symp-

tom has been corrected by the replacement PC
board.

NOTE: Allow the machine to heat up so that all

electrical components can reach their
operating temperature.

5. Remove the replacement PC board and substitute

it with the original PC board to recreate the original
problem.

a. If the original problem does not reappear

by substituting the original board, then the
PC board was not the problem. Continue
to look for bad connections in the control
wiring harness, junction blocks, and termi­nal strips.

b. If the original problem is recreated by the

substitution of the original board, then the
PC board was the problem. Reinstall the
replacement PC board and test the
machine.

6. Always indicate that this procedure was followed

when warranty reports are to be submitted.

NOTE: Following this procedure and writing on the

warranty report, “INSTALLED AND SWITCHED
PC BOARDS TO VERIFY PROBLEM,” will help
avoid denial of legitimate PC board warranty
claims.

TROUBLESHOOTING & REPAIR

F-3 F-3

PC BOARD TROUBLESHOOTING PROCEDURES

WARNING

ATTENTION
Static-Sensitive
Devices
Handle only at
Static-Safe
Workstations

Reusable
Container
Do Not Destroy

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PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-4 F-4

Observe Safety Guidelines TROUBLESHOOTING GUIDE
detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

PROBLEMS
(SYMPTOMS)

POSSIBLE AREAS OF
MISADJUSTMENT(S)

RECOMMENDED
COURSE OF ACTION

OUTPUT PROBLEMS

Major physical or electrical dam­age is evident when the sheet
metal cover(s) are removed.

1. Contact your local authorized
Lincoln Electric Field Service
Facility for technical assistance.

1. Contact the Lincoln Electric
Service Department,

1-888-935-3877

Machine is dead – no output – no
fan – no status indicator lights.

1. Make sure that the input power
switch is in the “ON” position.

2. Check the input voltage at the
machine. Input voltage must
match the rating plate.

3. Check for blown or missing
fuses in the input lines and the
1A slow blow fuse on the input
board.

1. Check the input power switch
for proper operation.

2. Check the leads associated
with the power switch for loose
or faulty connections. See the
Wiring Diagram.

3. Check all connectors and wires

for loose or faulty connections.

4. Perform the Input Voltage

Board Test.

Machine is malfunctioning - no
output - no status indicator lights ­fans run.

1. Check the input voltage at the
machine. Input voltage must
match the rating plate.

1. Check all connectors and wires
for loose or faulty connections.
See Wiring Diagram.

2. Perform the Input Voltage

Board Test.

3. The control board may be
faulty. Replace.

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PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-5 F-5

TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

PROBLEMS
(SYMPTOMS)

POSSIBLE AREAS OF
MISADJUSTMENT(S)

RECOMMENDED
COURSE OF ACTION

FUNCTION PROBLEMS

The machine powers up properly, but there is no response (no air flow or pilot arc) when the torch trigger is pulled. Only the power LED is lit.

1. Make sure the torch handle or
cable is not damaged or pulled
from the machine. Replace if
necessary.

2. Make sure the air supply is

converted and operating
properly.

1. Check all connectors and wires
for loose or faulty connections.
See Wiring Diagram.

2. Perform the Air/Gas

Solenoid Test.

3. The control board may be
faulty. Replace.

The machine powers up properly, but only air flows when the torch trigger is pulled; no pilot arc is established.

1. Make sure the torch consum­ables are in place and in good
condition. Replace if neces­sary.

2. Set air pressure at 65psi.

3. Make sure there are no kinks or
restrictions for air flow in the
torch cable.

4. Make sure that the correct size
nozzle is being used. Must be a
.028 orifice. Pro-Cut 55 size
nozzles will not work with the
Pro-Cut 25 system.

1. Check all connectors and wires
for loose or faulty connections.
See Wiring Diagram.

2 Perform the Torch Continuity

and Solenoid Test.

3. Perform the Main Inverter
Board Voltage and
Resistance Tests.

4. The control board may be
faulty. Replace.

The machine powers up properly,
and cuts OK with 230 input
applied. With 115 applied the pilot
arc ignites but goes out when cut­ting commences. Or, no pilot or
cutting when 115 input is supplied.

1. CP leads to its terminal from the
input to the inverter board are
loose or disconnected.

1. Reconnect the leads to its cor­rect terminal per the wiring dia­gram.

2. Perform the Input Board Test.

3. The input board may be faulty.

Replace.

The air begins to flow when the
torch trigger is pulled. There is a
very brief pilot arc. (Normal is 3
Seconds.) The sequence is repeat­ed with subsequent trigger pulls.

1. Check the input voltage at the
machine. Input voltage must
match the rating plate.

2. Make sure the torch
consumable parts are in place
and in good condition.
Replace if necessary.

3. Make sure there are no kinks or
restrictions for air flow in the
torch cable.

4. Make sure the air pressure is
set at 65psi.

5. Make sure that the correct size

nozzle is being used. Must be a
.028 orifice. Pro-Cut 55 size
nozzles will not work with the
PC 25 system.

1. Check all connectors and wires
for loose or faulty connections.
See Wiring Diagram.

2. Perform the Main Inverter

Board Voltage and
Resistance Tests.

3. The control board may be
faulty. Replace.

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PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-6 F-6

Observe Safety Guidelines

TROUBLESHOOTING GUIDE

detailed in the beginning of this manual.

PROBLEMS
(SYMPTOMS)

POSSIBLE AREAS OF
MISADJUSTMENT(S)

RECOMMENDED
COURSE OF ACTION

FUNCTION PROBLEMS

The cutting arc starts but sputters badly.

1. Make sure the operating proce­dure is correct for the process.
See the Operation section of
the manual.

2. Make sure the work clamp is
connected tightly to the work
piece.

3. Make sure the torch consum-

able parts are in place and in
good condition. Replace if
necessary.

4. Make sure the air pressure is

set at 65psi.

5. Make sure the air supply is not

contaminated with oil or
excessive water.

1. Check all connectors and
wires for loose or faulty con­nections. See Wiring Diagram.

2. Perform the Torch Continuity

and Solenoid Test.

3. Perform the Main Inverter

Board Voltage and Resistance
Tests.

4. The control board may be

faulty. Replace.

5. Use the correct extension cord.

See the instruction manual.

The pilot arc is normal, but the arc will not transfer to the work piece.

1. Make sure the operating
procedure is correct for the
process. See the Operation
section of the manual.

2. Make sure the work clamp is
connected tightly to the work
piece.

3. The work piece must be electri­cally conductive material, and
the work clamp must make a
good electrical connection with
the work piece.

4. Do not use a drag cup. Not
recommended for Pro-Cut 25
use.

1. Check all connectors and
wires for loose or faulty con­nections. See Wiring Diagram.

2.

Perform the Main Inverter

Board Voltage and Resistance
Tests.

3. The control board may be

faulty. Replace.

Trigger or purge is activated brief
air flow then the safety light illumi­nates.

1. The Control Board is defective.

Replace.

Poor performance of pilot arc or cutting. Poor consumable life.

1. Check pressure switch to be
functioning correctly
(opening/closing) at its correct
pressure.

2. Check pressure gauge to be
correct in its reading.

3. Check for recommended flow
rate coming from the torch end
with a flow meter.

1. Try increasing or decreasing the
air pressure to see if conditions
improve.

2. Replace regulator or pressure
switch may be required.

3. Screen in air line at inlet to air
solenoid may be clogged.
Clean. (no screen before 7/1/02)

4. Ensure that air is clean and dry
External filters may be used.

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PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-7 F-7

Observe Safety Guidelines

TROUBLESHOOTING GUIDE

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed.
Call 1-888-935-3877.

PROBLEMS
(SYMPTOMS)

POSSIBLE AREAS OF
MISADJUSTMENT(S)

RECOMMENDED
COURSE OF ACTION

FUNCTION PROBLEMS

Will only cut thin gauge material or cutting cutting is 1/2 of what it should be. Cuts for 3 seconds then quits.

The ground lead or clamp is dis­connected. Unit is not transferring
to cut mode.

1. Replace or repair, clamp or
cable.

2. Clamp directly to the piece to
be cut.

3. Look for the transfer signal from
the inverter board to the control
Board per the enhanced dia­gram.

4. Possible replacement of the
inverter board per the signal of
the enhanced diagram.

5. Possible replacement of the
Control Board per the signal of
the enhanced diagram.

6. Use the correct extension cord.
See the instruction manual.

When nothing is described for your problem, or you have performed your test with no solution.

1. Unplug and re-plug in all the
printed circuit board harness
connectors.

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PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-8 F-8

Observe Safety Guidelines

TROUBLESHOOTING GUIDE

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed.
Call 1-888-935-3877.

PROBLEMS
(SYMPTOMS)

POSSIBLE AREAS OF
MISADJUSTMENT(S)

RECOMMENDED
COURSE OF ACTION

LED FUNCTION PROBLEMS

The Thermal LED is lit after normal use.

1. One of the machine’s thermal
protection circuits has tripped.
Do not turn the PRO-CUT 25 off.
Allow the machine to cool. The
thermal protection circuits will
reset themselves.

2. Either the duty cycle has been
exceeded, the fan is not func­tioning, or the louvers are
blocked.

3. Thermo light comes on when
over voltage occurs +/-10%
must be with in 10%.

1. Check all connectors and wires
for loose or faulty connections.
See Wiring Diagram.

2. The inverter board may be
faulty. Replace.

3. The control board may be faulty.
Replace.

4. Use the correct extension cord.
See the instruction manual.

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TROUBLESHOOTING & REPAIR

F-9 F-9

PRO-CUT 25

INPUT FILTER CAPACITOR DISCHARGE PROCEDURE

WARNING

Service and repair should be performed by only Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in danger to
the technician or machine operator and will invalidate your factory warranty. For your
safety and to avoid electrical shock, please observe all safety notes and precautions
detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

This procedure will drain off any charge stored in the four capacitors that are part of the
Inverter Board assembly. This procedure MUST be performed, as a safety precaution,
before conducting any test or repair procedure that requires you to touch internal
components of the machine.

MATERIALS NEEDED

4mm Allen Wrench

Volt/Ohmmeter

7mm Nut Driver

Crescent Wrench

Insulated Gloves

Insulated Pliers

High Wattage Resistor - 25 to 1000 ohms, 25 watts minimum

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TROUBLESHOOTING & REPAIR

F-10 F-10

PRO-CUT 25

ELECTRIC SHOCK can kill.

• Have an electrician install and service
this equipment.

• Turn the input power off at the fuse box
before working on equipment.

• Do not touch electrically hot parts.

• Prior to performing preventative maintenance,
perform the following capacitor discharge procedure
to avoid electric shock.

DISCHARGE PROCEDURE

1. Remove input power to the PRO-CUT 25 machine.

2. Remove carrying handle using a 4mm allen

wrench.

3. Using a crescent wrench, carefully remove the

plastic nut from around the pressure regulator
located on the top of the machine.

4. Using a 7mm nut driver, remove the case

wraparound.

5. Be careful not to make contact with the capacitor
terminals located at the top of the main inverter
Board.

6. Obtain a high resistance and high wattage resistor
(25-1000 ohms and 25 watts minimum). This
resistor is not supplied with machine. NEVER USE
A SHORTING STRAP FOR THIS PROCEDURE.

7. Locate the eight capacitor terminals located at the
top rear of the main inverter board. See Figure F.1

8. Use electrically insulated gloves and insulated pli­ers. Hold the body of the resistor and connect the
resistor leads across the two capacitor terminals.
Hold the resistor in place for 10 seconds. DO NOT
TOUCH CAPACITOR TERMINALS WITH YOUR
BARE HANDS.

9. Repeat the discharge procedure for the other

capacitors.

10. Check the voltage across the terminals of all

capacitors with a DC voltmeter. Voltage should
be zero. If any voltage remains, repeat this
capacitor discharge procedure.

WARNING

CAPACITOR

TERMINALS

POWER

RESISTOR

INSULATED

GLOVES

INSULATED

PLIERS

RIGHT SIDE OF MACHINE

FIGURE F.1 – LOCATION OF INPUT FILTER CAPACITOR TERMINALS

INPUT FILTER CAPACITOR DISCHARGE PROCEDURE (continued)

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TROUBLESHOOTING & REPAIR

F-11 F-11

PRO-CUT 25

WARNING

MAIN INVERTER BOARD RESISTANCE TEST

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

This test will determine if the main inverter board has any “shorted” or “leaky” power diodes
or Insulated Gate Bipolar Transistors IGBT’s. Also it will indicate if P1 is “shorted” or “open”.

MATERIALS NEEDED

Analog Volt/Ohmmeter

Wiring Diagram

7mm Nut Driver

4mm Allen Wrench

Crescent Wrench

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TROUBLESHOOTING & REPAIR

F-12 F-12

PRO-CUT 25

MAIN INVERTER BOARD RESISTANCE TEST (continued)

FIGURE F.2

TEST PROCEDURE

1. Remove main input power to the PRO-CUT

25.

2. Remove carrying handle using a 4mm allen
wrench.

3. Using a crescent wrench, carefully remove the

plastic nut from around the pressure

regulator located on the top of the machine.

4. Using a 7mm nut driver, remove the case

wraparound.

5. Perform the Input Filter Capacitor Discharge

Procedure detailed earlier in this section.

6. Visually check for burned or damaged compo-

nents. If any components are physically dam-

aged or determined to be faulty, the Main

Inverter Board should be replaced.

7. Check the input rectifier bridge (P1) for

shorts or opens. See Figure F.2

RIGHT SIDE OF MACHINE

(NZL)
WRK

(EL)

Harness
Plug

Plug J1

LEAD 3

LEAD 2

P1

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TROUBLESHOOTING & REPAIR

F-13 F-13

PRO-CUT 25

MAIN INVERTER BOARD RESISTANCE TEST (continued)

FIGURE F.3 LOCATION OF IGBTS (6)

RIGHT SIDE OF MACHINE

(NZL)
WRK

(EL)

Harness
Plug

Plug J1

LEAD 3

LEAD 2

IGBT’s

(6)

8. Check the IGBTs for “shorts”. Check each IGBT (6)
from Gate to Collector. Normal resistance is approx­imately 100 ohms.

Also check each device from Gate to Emitter.

Normal resistance is approximately 40 ohms.
Check each device from Emitter to Collector.

Normal reading is high resistance in one polarity
and a low resistance in the opposite polarity.

Note: These devices will usually fail “short”resulting
in a zero or very low resistance reading. If they
“open” physical damage should be evident.

GCE

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TROUBLESHOOTING & REPAIR

F-14 F-14

PRO-CUT 25

MAIN INVERTER BOARD RESISTANCE TEST (continued)

9. Check Diodes D1, D2, & D3 for “shorts” or
“opens”. Keep in mind that unless these devices
are electrically isolated from the circuit, some
resistance will be read in both polarities. See the
Wiring Diagram.

RIGHT SIDE OF MACHINE

(NZL)
WRK

(EL)

Harness
Plug

Plug J1

LEAD 3

LEAD 2

D3

D2

D1

D3

D2

D1

D1, D2, & D3

Figure F.4

RIGHT SIDE OF MACHINE

(NZL)
WRK

(EL)

Harness
Plug

Plug J1

LEAD 3

LEAD 2

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TROUBLESHOOTING & REPAIR

F-15 F-15

PRO-CUT 25

10. Remove the torch consumables. (Shield
cup, Nozzle and Electrode)

11. With the Torch Consumables removed test
the output diodes. (D10 and D11) See the
Wiring Diagram.

12. With the Torch Consumables removed test
the snubber diodes. (D8 and D9) See the
Wiring Diagram. See Figure F.5.

13. Replace the torch consumables
previously removed. Check the resistance
across output diode D11. The resistance
should be very low, near or at zero ohms.
This verifies that the pilot arc circuit is
complete. See the Wiring Diagram.

MAIN INVERTER BOARD RESISTANCE TEST (continued)

D10

D8

D9

D11

Figure F.5

NOTES

F-16 F-16

PRO-CUT 25

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TROUBLESHOOTING & REPAIR

F-17 F-17

PRO-CUT 25

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INPUT BOARD VOLTAGE TEST

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

This test will help determine if the correct input voltage is being applied to the input board
and will also determine if the correct voltages are being processed and regulated on the
input board.

MATERIALS NEEDED

Volt/Ohmmeter

7mm Nut Driver

4mm Allen Wrench

Crescent Wrench

WARNING

TEST PROCEDURE

1. Remove input power to the PRO-CUT 25
machine.

2. Remove carrying handle using a 4mm
allen wrench.

3. Using a crescent wrench, carefully
remove the plastic nut from around the
pressure regulator located on the top of
the machine.

4. Using a 7mm nut driver, remove the case
wraparound.

5. Perform the Capacitor Discharge

Procedure detailed earlier in this
section.

6. Visually check for burned or damaged

components on the input board. If any
components are physically damaged or
determined to be faulty (except the fuse)
the input board should be replaced.

7. Check fuse F1 (1 amp). Replace if

defective.

8. Apply 115VAC input to the PRO-CUT 25
machine. The test should be performed
with 115VAC applied. Not 230VAC.

Note: If the peak input voltage is above
400VAC the thermal light may activate.
Reduce the input voltage.

9. Turn on the machine and carefully check
for 115VAC (+/- 10%) at points A and B.
See Figure F.6. See the Wiring
Diagram.

Note: Within 4 seconds of the machine
being turned on, the two relays RL2 and
RL3 should activate. If they don’t, the
input board is faulty.

TROUBLESHOOTING & REPAIR

F-18 F-18

PRO-CUT 25

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INPUT BOARD VOLTAGE TEST (CONTINUED)

A

B

RL2

RL3

F1

AC

AC

CP

V1

V2

PLUG CN1

1 2 3 4 5 6 7 8

TEST POINTS

Figure F.6 Input Board Description

TROUBLESHOOTING & REPAIR

F-19 F-19

PRO-CUT 25

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10. After the relays activate check for
115VAC from both test points AC to
CP. See Figure F.7. If this voltage is
not present or low, the relay contacts
may be defective.

11. Check the fan voltage at the fan
terminals (V1 & V2). See Figure F.7
Normal is 230VAC. If this voltage is
normal (230VAC) the primary circuit of
the auxiliary transformer is operating
correctly.

12. Check for the presence of
approximately 15VAC at pins 1 and 2
of plug CN1. See Figure F.7.

13. With the torch consumables in place
(nozzle, electrode and shield) check
for the presence of approximately
6VDC at pins 3(-) and 4(+) of plug CN1.
See Figure F.7.
Note: With the torch consumables
removed this voltage should be
approximately 26VDC.

14. If the relays (RL2 and RL3) are activating
with 115VAC applied to the machine
and the above test voltages are correct
the input board is functioning correctly.

INPUT BOARD VOLTAGE TEST (CONTINUED)

A

B

RL2

RL3

F1

AC

AC

CP

V1

V2

PLUG CN1

1 2 3 4 5 6 7 8

Figure F.7 Input Board Test Points

Fan
Leads

NOTES

F-20 F-20

PRO-CUT 25

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F-21 F-21

PRO-CUT 25

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TROUBLESHOOTING & REPAIR

MAIN INVERTER BOARD VOLTAGE TEST

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

This test will help determine if the main inverter board is receiving the correct input voltages
and if the correct regulated voltages are being processed and maintained by the main
inverter board.

MATERIALS NEEDED

Volt/Ohmmeter

7mm Nut Driver

4mm Allen Wrench

Crescent Wrench

WARNING

TEST PROCEDURE

1. Remove input power to the PRO-CUT
25 machine.

2. Remove carrying handle using a 4mm
allen wrench.

3. Using a crescent wrench, carefully
remove the plastic nut from around the
pressure regulator located on the top of
the machine.

4. Using a 7mm nut driver, remove the case
wraparound.

5. Perform the Capacitor Discharge

Procedure detailed earlier in this
section.

6. Visually check for burned or damaged

components on the input board. If any
components are physically damaged or
determined to be faulty (except the
fuse) the input board should be
replaced.

7. Apply the correct input power to the
Pro-Cut 25 machine. (115VAC or
230VAC)

8. Carefully test for approximately 300VDC
at the P1 bridge terminals.
See Figure F.8. This represents the
rectified voltage supplied from the input
board. See the Wiring Diagram.

9. Carefully test for approximately 15VAC
at the test points on bridge P2. This is
the control supply voltage from the
input board. See Figure F.8. See the
Wiring Diagram.

10. Carefully test for 12VDC at test points
C17. See Figure F.8. See Wiring
Diagram. This is the rectified and
regulated DC supply voltage for the
inverter board control circuitry.

TROUBLESHOOTING & REPAIR

F-22 F-22

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

MAIN INVERTER BOARD VOLTAGE TEST (CONTINUED)

RIGHT SIDE OF MACHINE

(NZL)
WRK

(EL)

Harness
Plug

Plug J1

LEAD 3

LEAD 2

P1

P2

C17

P2

C7

C18

C19

AC

AC

+

+

+

Figure F.8. Test Points

10. Carefully test for 12VDC at test points
C7. See Figure F.9. See the Wiring
Diagram. This is the rectified and
regulated supply for the pulse width
modulation circuit.

11. Carefully test for 12VDC at C18 test
points. If it is not correct the control
board or associated wiring may be
faulty. See the Wiring Diagram. See
Figure F.9.

12. Carefully check for the presence of
8VDC at C19 test points. If not correct
the control board or associated wiring
may be faulty. See Figure F.9.
See the Wiring Diagram.

TROUBLESHOOTING & REPAIR

F-23 F-23

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

MAIN INVERTER BOARD VOLTAGE TEST (CONTINUED)

RIGHT SIDE OF MACHINE

(NZL)
WRK

(EL)

Harness
Plug

Plug J1

LEAD 3

LEAD 2

P1

P2

C17

P2

C7

C18

C19

AC

AC

+

+

+

+

+

Figure F.9 Test Points

NOTES

F-24 F-24

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TORCH CONTINUITY AND SOLENOID TEST

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

This procedure will help the technician determine if the torch cable, consumables and elec­trode solenoid are functioning properly.

MATERIALS NEEDED

Volt/Ohmmeter
12 VDC @ 1 Amp Power Supply
7mm Nut Driver
4mm Allen Wrench
Crescent Wrench

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-25 F-25

PRO-CUT 25

WARNING

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-26 F-26

PRO-CUT 25

TORCH CONTINUITY AND SOLENOID TEST (continued)

TEST PROCEDURE

1. Remove input power to the PRO-CUT 25
machine.

2. Remove carrying handle using a 4mm allen
wrench.

3. Using a crescent wrench, carefully remove
the plastic nut from around the pressure
regulator located on the top of the machine.

4. Using a 7mm nut driver, remove the case
wraparound.

5. Perform the Capacitor Discharge

Procedure.

6. Remove Plug J1, Lead #2, and Lead #3 from
the Main Inverter Board. See Figure F.10

7. Using the ohmmeter, check the torch
resistances per Table F.1.

8. If any of the resistance checks are not cor­rect, the torch assembly may be faulty.
Repair or replace.

9. With connector J1 disconnected from the
P.C. Board carefully apply the 12 VDC supply
to the electrode solenoid. (positive to Plug
J1 Pin #4 and Negative to Pin #3). The elec­trode solenoid should activate. Listen for the
solenoid action in the torch handle. If the
solenoid does not activate, it may be faulty.
Replace. See Figures F.10 & F.11.

FIGURE F.10

(NZL)
WRK

(EL)

Harness
Plug

Plug J1

LEAD 3

LEAD 2

Red Leads

Blue Leads

Torch Solenoid

Vent Tube

Electrode Lead

Air Hose

White & Black Pairs

Connector

ELECTRODE

BODY (nozzle)

Electrode is

insulated from
Brass Body

outside

center

flex tubes

Pilot path / air tube

crimp

fitting

N.O.

Torch Trigger

EL (3)

3
4

NZL (2)

1
2

TROUBLESHOOTING & REPAIR

F-27 F-27

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TORCH CONTINUITY AND SOLENOID TEST (continued)

TABLE F.1 - TORCH ASSEMBLY RESISTANCES

TEST CIRCUIT(S) BEING EXPECTED TEST

POINTS TESTED RESISTANCE CONDITIONS

Lead #2 Pilot arc 1.5 ohms maximum Torch consumables

To Lead #3 leads in place

Lead #2 to Torch Pilot arc lead to 1.0 ohm maximum Torch consumables

Nozzle nozzle in place

Lead #3 to Torch Pilot arc lead to 1.0 ohm maximum Torch consumables

Nozzle nozzle in place

Pin 1 to Pin 2 Torch trigger circuit 100K ohms minimum Torch trigger NOT

Plug J1 (Red Leads) pulled (not activated)

Pin 1 to Pin 2 Torch trigger circuit 1.0 ohm maximum Torch trigger pulled

Plug J1 (Red Leads) (activated)

Pin 3 to Pin 4 Electrode Solenoid 45 to 55 ohms None

Plug J1 (Gray Leads)

10. Torch circuits may be measured when elec­trode and nozzle are in place if the various cir­cuits are isolated from each other. NZL (2),
Electrode (3), Trigger (1,2), and Torch leads (3,4)
should all measure greater than 1 Meg ohm when
checked as isolated circuits. See Figure F.10
Diagram.

11. Replace leads and plugs previously
removed.

(LEAD 2) NZL

WRK

(LEAD 3) EL

Harness
Plug J1

1

2

3

4

Figure F.11

NOTES

F-28 F-28

PRO-CUT 25

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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-29 F-29

PRO-CUT 25

WARNING

AIR/GAS SOLENOID TEST

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

This procedure will help the technician determine if the solenoid is functioning properly.

MATERIALS NEEDED

4mm Allen Wrench

7mm Nut Driver

12 VDC @ 3 Amp Power Supply

Volt/Ohmmeter

Crescent Wrench

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-30 F-30

PRO-CUT 25

AIR/GAS SOLENOID TEST (continued)

TEST PROCEDURE

1. Remove input power to the PRO-CUT 25
machine.

2. Remove carrying handle using a 4mm allen
wrench.

3. Using a crescent wrench, carefully remove
the plastic nut from around the pressure
regulator located on the top of the machine.

4. Using a 7mm nut driver, remove the case
wraparound.

5. Perform the Input Capacitor Discharge
Procedure detailed earlier in this section.

6. Locate the air solenoid and leads. Carefully
remove the two leads from the Solenoid. See
Figure F.12.

7. Check the coil resistance of the solenoid at
the two terminals. Normal resistance is
approximately 13 ohms. If the resistance is
abnormal, the Solenoid may be defective.

8. Carefully apply the 12 VDC supply to the

solenoids lower two terminals. With proper
air pressure applied, the solenoid should
activate and air should flow from the torch
nozzle. If the solenoid activates but air does
not flow, check for a restriction in the air line
or torch.

9. Reinstall the two leads previously removed.

FIGURE F.12 – AIR SOLENOID

LEFT SIDE OF MACHINE

A

B

Air Solenoid

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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-31 F-31

WARNING

CONTROL BOARD REMOVAL AND REPLACEMENT

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

The following procedure will aid the technician in removing the control board for maintenance
or replacement.

MATERIALS NEEDED

Crescent Wrench

Small Flathead Screwdriver
7mm Nut Driver
6mm Nut Driver
4mm Allen Wrench

2.5mm Allen Wrench
Needle Nose Pliers

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-32 F-32

PROCEDURE

1. Remove input power to the PRO-CUT 25 machine.

2. Remove carrying handle using a 4mm allen
wrench.

3. Using a crescent wrench, carefully remove the
plastic nut from around the pressure regulator
located on the top of the machine.

4. Using a 7mm nut driver, remove the case wrap­around.

5. Perform Capacitor Discharge Procedure.

6. Using a very small flathead screwdriver or a thin
knife blade, carefully remove the red plastic cap
from the front of the plastic OUTPUT knob located
on the front of the machine. See Figure F14.

CONTROL BOARD REMOVAL AND REPLACEMENT (continued)

L

IN

C

O

L

N

E

L

E

C

T

R

IC

PRO-CUT 25

ON

OFF

PURGE

P

OW

ER

GAS PR

ESSURE

T

HERMAL

SAFETY

!

R
E

Q
U

I
R
E
S

2
0
A

/
1
1
5
V

B
R

A
N
C

H
C

I
R
C
U
I
T

R
E

Q
U
I

R
E
S

3
0
A

/
1
1
5
V

B
R

A
N
C

H
C

I
R
C
U
I
T

2
5

2
0

1
5

Small Red
Cap

FIGURE F.13 - CONTROL BOARD LOCATION

FIGURE F.14 - SMALL RED CAP REMOVAL

L

IN

C

O

L

N

E

L

E

C

T

R

I

C

PRO-CUT 25

ON

OFF

PURGE

PO

WER

G

AS PRESSURE

TH

ERM

A

L

SAFETY

!

R

E
Q

U
I
R

E
S

2
0
A
/

1
1
5
V

B
R

A
N
C
H

C
I
R
C

U
I
T

R

E
Q

U
I
R
E

S
3

0
A
/

1
1
5
V

B
R

A
N
C
H

C
I
R
C

U
I
T

2
5

2
0

1
5

Control
Board

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

7. A nut is located under the red plastic piece that you
previously removed. Loosen this nut with a 6mm
nut driver and remove. Plastic alignment spacer
may come off with knob.

8. Next to the knob is a Red button that reads
“PURGE”. Remove it by gently pulling.

Be sure to follow the recommended static­free methods for handling printed circuit
boards. Failure to do so can result in per­manent damage to the equipment.

9. Using a 7mm nut driver remove the three screws
that hold the case front to the central metal wall.
(This will allow the case front to be gently pulled
forward so the Control board can be removed.)
See Figure F.15.

10. Remove the Four allen bolts with a 2.5 mm allen

wrench.

11. Carefully remove the plug and lead assembly from
the control board.

12. At this point, the control board is ready for

removal. GENTLY pull the case front forward and
carefully remove the Control board.

13. Replace the Control Board by GENTLY pulling the
case front forward and carefully sliding the
Control board back into its original position .
Reconnect plug and lead assembly.

14. Replace the four allen mounting screws.

15. Replace the screws connecting the case front to

the central metal wall.

TROUBLESHOOTING & REPAIR

F-33 F-33

L

IN

C

O

L

N

E

L

E

C

T

R

IC

PRO-CUT 25

O

N

O
FF

PU

R

G

E

P

O

W

E

R

G

A

S

P

R

E

S

S

U

R

E

T

H

E

R

M

A

L

S

A

F

E

T

Y

!

R
E

Q
U
I

R
E
S

2
0

A
/
1
1
5

V
B
R

A
N

C
H

C
I
R

C
U

I
T

R
E

Q
U
I
R

E
S

3
0

A
/
1
1
5

V
B
R

A
N
C

H
C

I
R

C
U

I
T

2

5

2
0

1
5

3 Screws

FIGURE F.15 - CASE FRONT SCREW REMOVAL

CONTROL BOARD REMOVAL AND REPLACEMENT (continued)

CAUTION

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

16. Replace the red PURGE button.

17. Replace the plastic OUTPUT knob,
align it in its original position, and
tighten nut.

18. Replace the red cap on the end of
the OUTPUT knob.

19. Replace the case wraparound.

20. Replace the plastic nut from around
the pressure regulator. Do Not

Over tighten.

21. Replace the carry handle.

TROUBLESHOOTING & REPAIR

CONTROL BOARD REMOVAL AND REPLACEMENT (continued)

F-34 F-34

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-35 F-35

WARNING

INPUT BOARD REMOVAL AND REPLACEMENT

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. 1-888-935-3877.

DESCRIPTION

The following procedure will aid the technician in removing the input board for maintenance
or replacement.

MATERIALS NEEDED

4 mm Allen Wrench

Crescent Wrench

7 mm Nut Driver

Needle Nose Pliers

PROCEDURE

1. Remove input power to PRO-CUT 25.

2. Remove carrying handle using a
4mm allen wrench.

3. Using a crescent wrench, carefully
remove the plastic nut from around the
pressure regulator located on the top of
the machine.

4. Using a 7mm nut driver, remove
the case wraparound.

5. Perform Capacitor Discharge Procedure.

Be sure to follow the recommended static-free
methods for handling printed circuit boards.
Failure to do so can result in permanent damage to
the equipment.

6. Note the orientation of the input
board to avoid confusion during
reassembly.

7. Carefully label and remove cooling fan
leads from Input Board. Pliers may be
necessary. See Figure F.17.

8. Remove harness plug from lower right
hand corner of board. Pliers may be
necessary. See Figure F17.

9. Directly above the harness in step 8,
there are four leads, CP(2) and AC(2).
Label these leads and remove. Pliers
may be necessary.

10. Using a 7mm nut driver, remove the two
leads from terminals A and B on the
input board. NOTE: The lead posts on
the Input Board are labeled with an “A”
and a “B”, so label the lead wires
accordingly upon removal. Be careful
not to misplace washers when bolts are
removed. See Figure F.17.

CAUTION

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-36 F-36

INPUT BOARD REMOVAL & REPLACEMENT (continued)

FIGURE F.16 Input Board Location

P

C

T

2

0

LIN

C

O

LN

EL

E

CT

R

IC

P

R

O

-C
U

T

25

O

N

OFF

P

U

RG

E

P

O
W

E

R

G

A

S

P
R

E
S

S
U

R
E

T
H

E
R

M
A

L

S
A

F
E

T

Y

!

R
E
Q
U

IR
E
S

2
0
A

/1
1
5
V

B
R
A
N
C

H
C

IR
C

U
IT

R
E
Q
U

IR
E
S
3

0
A
/

1
1
5
V
B

R
A
N
C

H
C

I
R
C
U

IT

2
5

2
0

1
5

1
2

Input Board

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

PRO-CUT 25

TROUBLESHOOTING & REPAIR

F-37 F-37

FIGURE F.17 – INPUT BOARD REMOVAL

Fan
Leads

Four
Leads

Switch
Leads

Mounting
Screws

Multi-colored
Plug

Mounting
Screws

A

B

AC
AC

CP

INPUT BOARD REMOVAL & REPLACEMENT (continued)

11. Using a 7mm Nut driver, remove the
four mounting nuts from the corners of
the Input Board. Be careful not to lose
the washer behind each nut. Input
Board can be removed after these four
nuts are removed.

12. After replacement of the Input
Board, replace the four nuts and
washers previously removed
from the corners of the board.
Do Not Over tighten.

13. Using a 7 mm nut driver replace
two leads originating from the
Input Switch. (A+B)

14. Reconnect four leads in their
correct positions. (AC and CP)

15. Reconnect the harness plug.

16. Reconnect the fan leads to the Input
Board. Be sure that leads are
connected to their original positions.

17. Replace the case wraparound.

18. Replace the plastic nut from around the
pressure regulator. Do Not Over

tighten.

19. Replace the carry handle.

NOTES

F-38 F-38

PRO-CUT 25

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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-39 F-39

WARNING

MAIN INVERTER BOARD REMOVAL AND REPLACEMENT

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

The following procedure will aid the technician in removing the MAIN INVERTER BOARD for
maintenance or replacement.

MATERIALS NEEDED

4mm Allen Wrench

Crescent Wrench

7mm Nut Driver

Needle Nose Pliers

CAUTION

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-40 F-40

FIGURE F.18 – MAIN INVERTER BOARD REMOVAL

MAIN INVERTER BOARD REMOVAL & REPLACEMENT (continued)

PROCEDURE

1. Remove input power to PRO-CUT 25.

2. Remove carrying handle using a
4mm allen wrench.

3. Using a crescent wrench,
carefully remove the plastic nut from
around the pressure regulator located
on the top of the machine.

4. Using a 7mm nut driver, remove
the case wraparound.

5. Perform Capacitor Discharge

Procedure.

Be sure to follow the recommended static-free

methods for handling printed circuit boards.

Failure to do so can result in permanent damage

to the equipment.

6. Locate the Main Board, all associated
leads and plug connections.

7. Label the leads and note their positions
for reassembly.

8. Using a 7mm Nut driver, remove the
four nuts and washers located at the
corners of the main board. (This will
allow you to gently manipulate the board
for labeling and removal of all Leads.)

9. Remove the two harness plugs from
front top corner of board. Label
and remove the four single leads from
the rear top corner of board. Carefully
remove NZL, WRK, and EL leads from
lower front of board. Also remove
harness plug (J1). See Figure F.19.

10. Remove board.

LINCOLN
ELECTRIC

PRO-CUT 25

ON

OFF

PURGE

P

O

W
E

R

G
A

S
P

R

E

S
S

U
R

E

T

H

E

R
M

A
L

S

A
F

E
T

Y

!

RE
Q
U

IR
E
S

20
A

/1
15V

B
R
A

N
C
H

C
IR
C

U
IT

R
E
Q
U
IR

E
S

30
A/1

1
5

V B
R
A

N
C
H

C
IR
C

U
IT

2
5

2
0

1
5

1

2

Main Board

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-41 F-41

FIGURE F.19 – INVERTER BOARD LEAD LOCATIONS

Leads

NZL

WRK

EL

Harness
Plug (J1)

Harness plugs

Lead

MAIN INVERTER BOARD REMOVAL & REPLACEMENT (continued)

11. Reconnect all leads to the new board.

12. Replace the four bolts and washers
previously removed from the corners of
the board.

13. Replace the case wraparound.

14. Replace the plastic nut from around the
pressure regulator. Do Not Over

tighten.

15. Replace the carry handle.

NOTES

F-42 F-42

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-43 F-43

WARNING

SWITCH

REMOVAL AND REPLACEMENT

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

The following procedure will aid the technician in removing the SWITCH for maintenance or
replacement.

MATERIALS NEEDED

4 mm Allen Wrench

Crescent Wrench

7 mm Nut Driver

Phillips Head Screwdriver

Flat Head Screwdriver

PRO-CUT 25

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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-44 F-44

FIGURE F.20 – SWITCH

L

IN

C

O

L

N

E

L

E

C

T

R

IC

PRO-CUT 25

O

N

O

FF

PU

R

G

E

P

O

W

E

R

G

A

S

P

R

E

S

S

U

R

E

T

H

E

R

M

A

L

S

A

F

E

T

Y

!

R
E
Q

U
I
R
E

S
2
0

A
/
1

1
5

V
B
R

A
N
C

H

C
I
R
C
U

I
T

R

E
Q

U
I
R
E
S

3
0
A

/
1
1

5
V

B
R
A

N
C

H
C

I
R
C
U

I
T

2

5

2
0

1
5

Switch

SWITCH

REMOVAL AND REPLACEMENT (continued)

PROCEDURE

1. Remove input power to PRO-CUT 25.

2. Remove carrying handle using a
4mm allen wrench.

3. Using a crescent wrench,
carefully remove the plastic nut from
around the pressure regulator located
on the top of the machine.

4. Using a 7mm nut driver, remove
the case wraparound.

5. Perform Capacitor Discharge

Procedure.

6. Using a phillips head screwdriver, remove
the two power switch mounting screws
located directly above and below the
power switch.

7. Carefully remove the power switch
assembly from the front of the machine,
making note of insulation positioning.

8. Carefully label and identify the four leads
and their terminals before removing.
These leads and their positions are not
labeled for you, so be sure to label them
accurately

9. After labeling the four leads, remove them
from the switch using a flathead
screwdriver.

10. After replacement of the switch,
reconnect the four leads making sure that
the switch is oriented correctly and the
insulation is positioned correctly.

11. Replace the case wraparound

12. Replace the plastic nut from around the
pressure regulator. Do Not Over tighten.

13. Replace the carry handle

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-45 F-45

WARNING

FAN REMOVAL AND REPLACEMENT

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician or
machine operator and will invalidate your factory warranty. For your safety and to avoid
electrical shock, please observe all safety notes and precautions detailed throughout this
manual.

If for any reason you do not understand the test procedures or are unable to perform the
test/repairs safely, contact the Lincoln Electric Service Department for electrical
troubleshooting assistance before you proceed. Call 1-888-935-3877.

DESCRIPTION

The following procedure will aid the technician in removing the fan for maintenance or
replacement.

MATERIALS NEEDED

4mm Allen Wrench

Crescent Wrench

7mm Nut Driver

Phillips Head Screwdriver

PRO-CUT 25

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-46 F-46

FIGURE F.21 – FAN LOCATION

L

IN

C

O

L

N

E

L

E

C

T

R

IC

PRO-CUT 25

O

N

O

FF

PU

R

G

E

P

O

W

E

R

G

A

S

P

R

E

S

S

U

R

E

T

H

E

R

M

A

L

S

A

F

E

T

Y

!

R
E
Q

U
I
R

E
S
2
0

A
/
1

1
5
V

B

R
A
N

C
H

C

I
R
C

U
I
T

R
E
Q

U
I
R
E

S
3
0

A
/
1

1
5
V

B
R

A
N

C
H

C
I

R
C
U

I
T

2
5

2

0

1

5

1
2

Fan

FAN REMOVAL AND REPLACEMENT (continued)

PROCEDURE

1. Remove input power to PRO-CUT 25.

2. Remove carrying handle using a
4mm allen wrench.

3. Using a crescent wrench, carefully
remove the plastic nut from around the
pressure regulator located on the top of
the machine.

4. Using a 7mm nut driver, remove
the case wraparound.

5. Perform Capacitor Discharge

Procedure.

6. Label and remove the two leads
connected to the top of the fan. Be
sure to correctly label these leads and
note their positions.

PRO-CUT 25

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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-47 F-47

FAN REMOVAL AND REPLACEMENT (continued)

7. Using a phillips head screwdriver,
remove the four mounting screws on
the four corners of the fan. The fan
will become free.

8. After replacement of the fan, replace
the four mounting screws located at
the corners of the fan.

9. Reconnect labeled leads to the
top of the fan. Be sure to replace
leads in their proper positions.

10. Replace the case wraparound.

11. Replace the plastic nut from around the
pressure regulator.

Do Not Over tighten.

12. Replace the carry handle.

RETEST AFTER REPAIR

Should a machine under test be rejected for any reason requiring the removal of any mechanical part that could
affect the machine’s electrical characteristics, or if any electrical components are repaired or replaced, the
machine must be retested.

Machine Input and Output

Input Volts/Hertz Input Current Rated Output

230/1/60HZ 15 Amps 20A @ 100% Duty Cycle

Output Current Range 12 - 25 Amps

Maximum Open Circuit Voltage 400 Volts

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING & REPAIR

F-48 F-48

PRO-CUT 25

Pilot Current 12 amps

Functional Test

1. Connect the machine to 230VAC and an air supply (70psi minimum).

2. Turn on the machine and verify the following:

- When the machine is turned on the Thermal LED turns on for approximately 1 second.

- The fan is functional.

- The power LED is lit.

3. Test the pressure switch in the following way:

-Press and hold the Purge button on the front of the machine. Using the regulator on the machine,
slowly lower the air pressure and verify that the gas pressure LED turns on at approximately 35 to

40 psi.

- With the gas pressure LED on, release the Purge button and then pull the trigger on the torch.
Verify that a pilot arc does NOT occur. Release the trigger.

- While again pressing the Purge button, slowly increase the air pressure using the regulator on the

machine until the gas pressure LED turns off. Verify that the LED turns off at approximately 40-45
psi.

- Continue to press the Purge button and set the air pressure at 65psi. Release the Purge button.

4. Test the Purge button safety function by again pressing the Purge button and then pulling the trigger on the

torch. Verify that a pilot arc does NOT occur. Release the trigger and the Purge button. (This is not a

repeat of the previous step, in this step the Purge button is pressed and the gas pressure LED is off.)

5. With no air flowing (postflow), pull the trigger on the torch. Verify that the air flows for 2 seconds (preflow)
and then the pilot arc is initiated. While continuing to hold the trigger, verify that the pilot arc remains lit for
3 seconds then turns off automatically. Release the trigger and verify that the air continues to flow for 10
seconds (postflow).

6. Remove the shield cup from the torch and verify that the safety LED turns on. Re-tighten the shield cup on
the torch and verify that the safety LED remains lit. Pull the trigger of the torch and verify that a pilot arc
does NOT occur. Turn the machine off and then back on to clear the safety error.

7. Turn the PRO-CUT 25 off.

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

G-1 G-1

PRO-CUT 25

ELECTRICAL DIAGRAMS

TABLE OF CONTENTS

-ELECTRICAL DIAGRAMS SECTION-

ELECTRICAL DIAGRAMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION G

WIRING DIAGRAM - PROCUT 25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-2

WIRING DIAGRAM W/ADDITIONAL INFO - PROCUT 25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-3

SCHEMATIC - CONTROL PRINTED CIRCUIT BOARD - SHEET 1 . . . . . . . . . . . . . . . . . . . . . . G-4

SCHEMATIC - CONTROL PRINTED CIRCUIT BOARD - SHEET 2 . . . . . . . . . . . . . . . . . . . . . . G-5

SCHEMATIC - CONTROL PRINTED CIRCUIT BOARD - SHEET 3 . . . . . . . . . . . . . . . . . . . . . . G-6

PC BOARD ASSEMBLY - MAIN INVERTER BOARD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-7

PC BOARD ASSEMBLY - INPUT BOARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-8

PC 25 TORCH DETAILS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-9

115/230/1/50/60 VAC

INPUT

CN1

2

1

4

3

5
6
7
8

300uH

L1

RL3

10/10W

R1

V2

V1

B

A

1A/250V

F1

RL2

RL2

RL2

AC

CP

CP

A

C

L1

RL1

RL2

115VAC

230V

T1

115V

RL1

L1

15VAC
15VAC
SAFETY
+28VDC
SEC GND
OVLOAD
115/230
+12VDC

AC

CP
CP

AC

CN2

6

9

10

2

20

15 16

+15Vrms

EV1

NO

COM

NC

12VDC

PS2

PS1

861793

OVLOAD

SEC GND

SAFETY

CN1

12 18 14 1 11 4 13 7 19 24 21 23 8 1 2 3

3

22

17

V+

+12VDC

+12VDC_SW

+8V_SW

SEC GND

OVLOAD

TRANSFER SW

TRANSFER

SOL 1 DRIVER

SOL 2 DRIVER

TRIGGER

OUTPUT

V_OUT

1 2 18 14 7 15 4 11 5 16 10 12 13

5

4

POT_WIPER

23

POT_CW

22

POT_CCW

24

CP

15K/3W

R1

15K/3W

R2

1500uF/250V

C2a,b

1500uF/250V

C

1a,b

C12

CP

C26

IRG4BC30W

Q1a,b,c

IRG4BC30W

Q2a,b,c

SEC

PRI

T2

C13

D10

D11

240uH

Lout

SHUNT

SH-

SH+

BS1

8A

+12VDC

TRANSFER

C14

6.8k/5W

R24

WRK

NZL (2)

EL (3)

CN3

2

1

3
4

12VDC

PT

WORK CLAMP

CN1

SW1

230VAC

FN1

+

+

RL1

Display LED's

Control Board

Output Control

Air


Solenoid



1

Purge

Switch

Input

Voltage Board

Main Inverter Board

Solenoid 2

G-2
WIRING DIAGRAM - PRO-CUT 25

ELECTRICAL DIAGRAMS

G-2

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.

PRO-CUT 25

pressure

Schematic 98056 (SIPC 25)

Schematic 99016 ( SPA25)

Schematic 98044

Purge Switch (n.o.)

Gas Psi

.

Thermo

Safety led

Input Power

8

vdc
when
open
for
correct
pressure

RL1

RL3

Auto
reconnect
card

RL1

(control bd

mounted)

50hz /60

hz

RPM’s 2700/ 3100
amps .13 / .12
runs all the time

Pcb

.

card

relay

Reconnect
pilot relay
+12 v

8vdc @ min

10-5

vdc

@ max.
(power supplies from
inverter bd.
for pot only!!)

This bd

generates 8 vdc

which get its input from

the inverter bd

. via the

12

vdc

on the inverter bd

.

8v is used on both

bds.

8vdc

(pip)

reset by turning off PC25

also

input overload

all LED’s come on

initally

then just the POWER led is lit
THERMO led stays lit for
approx

3 sec also at turn on.

12v=230
0v =115

+15Vrms

( reed )

( relay )

Soft start relay
3 to 5 sec delay
(12

vdc

)

Soft start resistor
( over heats on 208 input !)

Shown in 230
de-energized

+12 VDC

sw

supply is used for:

1. Output control (control).
& its ref bd. (invert)

2. Shunt feedback ( invert)

3. Transfer relay (invert & control)

4. Torch solenoid (

inv

& control)

5. LED supply

+8 VDC supply is used for:

1. Turn on PWM (invert)

2. PIP detect

ckt.(control)

3. Pilot arc timer (control)

4. Purge

ckt

button(control)

5. Drivers for LED logic (control)

6. Torch solenoid logic

ckt(control)

7. Air solenoid logic

ckts

& driver (control)

8. Transfer relay (inve rt) Logic &driver(control)

Represents:

board soldered to

a mother

bd

.

Represents:

relay soldered to

a mother

bd

.

DC

REF bd

card

PWM

driver

card

PWM

card

reg

+12V

( pwm gate drive signal)

+12

vdc

+15Vrms

PT3

amp

shunt input

+12V

inverter bd

.

inverter bd

.

common for

trigger

pink

pink

230vac

Auto reconnect

ckt

.

PIP supply 20

vac

{

Supply for torch,&

main air solenoid .

12 V regulator

on inverter bd

.

Vs =OK

0v= over

load.

{

over
volts

signal

{

{

This is the voltage

reconnect for 110V
operation
(voltage

doubler

)

operating

freq

. 63

khz

/ 100khz

(PC 25) / (PC20)

All

thermo devices are on this

inverter board

primary current

feedback c.t.

primary c.t.

( air )

( torch)

Q4

Reco

nnect

mai

nrelay

+12V

Aux

fuse

OVL signal

+8 = on (from

control bd.)

isolated

+20

Vdc

for NO parts in place(pip)

+6

Vdc

with parts IN

4.7nf

4kv

4.7 f

4kv

To

pwm

chip

sec

thermo

PT2

(N.C.)

F.e.t.

thermo

PT1

(N.C.)

some

‘s

some

‘s

300

VDC

Mai

n

Cap

s.

to

nozzle

ckt

.

*does it work

in the other input

voltage 115v or 230 v ?

If it does, it is an

input

bd

.

Listen for relay to

click

in

after a 3 sec delay

On f

or 110v

ac

+8v = no output
6v = output

To

{

+12v =pilot

0 = cutting

To

{

+8v = open trigger to

Choke

Thermo

( PCT)

PT3(N.O.)

+ 12 from Control bd

.

Reed switch (BS1)

closes when cutting

current is drawn

To Control bd

.

400Vocv
100v pilot &cutting
25a @ 35% duty (115 input)
25a @ 60% duty (230 input)

12 to 25 amps range

3/8 max thickness @ 30 amp input

+8V

direct to control bd..

+12v = sol off

0v = sol on

Must be

a
PC 25 nozzle!
S22147-028

no drag cups either

!

try without.

Must be to within

1/8 ” to transfer to cut.

cutting

+12V_

sw

Transfer relay

(signal from

control

bd

.)

shown in pilot

2.2 f/400v

Must double hit

when first turned on
input ( safety feature)

or after

thermo

reset

not so in

preflow

.

Torch solenoid:

supply from inverter

bd

.

Control is from control

bd

.

45 to 55 ohms

Cuts for 3 sec then quits

(stuck in pilot mode )
or
pilot current is 1/2 of
cutting current

EV2

Trigger:

8v when open

reg

+8

vdc

+12V_sw

8V

i

nput

+8

comes “on” at turn on

for 3 sec.

“see” pip

ckt

inset detail

“see” pip

ckt

inset detail

Scaled

down

version

of

output

+12

V= ok
0v = overload

(choke thermo or input bd

.)

2 f

400v

RHRG30120

PILOT PATH

PIP PATH

CUTTING PATH

PIP

PILOT

CUTTING

choke

5

00
V

Must be within
+/- 10% of input.
Must be greater than 208v.

YES for Ranger 250 series
Commander 300, 400 ,500’s

Auto Reconnect Feature

Air

Guage

Supply pressure must be:
80 to 150

psi

with a flow

rate of no less than 4.0

cfm

(113 l/min.)

240

cfh

Set air pressure while in
purge

to

65

psi

.

comes on if

no gas

psi

.

( over volt detect )

CN1-3

CN1-7

Input bd

Inverter bd

Control bd

.

20

vac

***

Detail***

PIP (safety

ckt

.)

CN1-4

CN1-3

CN2-11

CN2-6

NZL

EL

+20 Vdc for NO parts
in place(pip)
+6

Vdc

with parts IN

LED
ckt.

10 K

torches of

15 or 25 ft are ok

all

ckt

. commons

0 170

65

50 150

Ckt

.

Ckt

.

Display

bd & Driver bd

.

indicates that
the +12 on inverter

bd

is up ( not the +8)

“see” pip

ckt

inset detail

PILOT
Current
is 12 amps

Typical input current draw:

115v 25A/35% = 37.7A
20A/60% = 26.7A
230v 25A/60% = 19A
20A/100%=15A

13

2 . 5

K

PRO CUT 25

file: procut25.pp
3-11-02 3-6-03
3-20-02

Closes @ 43.5

psi

(3bars)

Opens@ 37.7 to 42

psi

(2.6 to 2.9 bars)

when in 230

115vac

115vac

when in 115

when in 115

R

e

m

o

ve

e

le

c

t

r

od

e

.

C

h

e

c

k

f

o

r

s

h

o

r

t

s

&

o

p

e

n

s

t

o

ot

h

e

r

l

ea

d

s

G-3
WIRING DIAGRAM W/ADDITIONAL INFO

ELECTRICAL DIAGRAMS

G-3

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.

PRO-CUT 25

G-4
SCHEMATIC- CONTROL PRINTED CIRCUIT BOARD - SHEET 1

ELECTRICAL DIAGRAMS

G-4

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.

PRO-CUT 25

G-5
SCHEMATIC- CONTROL PRINTED CIRCUIT BOARD - SHEET 2

ELECTRICAL DIAGRAMS

G-5

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.

PRO-CUT 25

G-6
SCHEMATIC- CONTROL PRINTED CIRCUIT BOARD - SHEET 3

ELECTRICAL DIAGRAMS

G-6

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.

PRO-CUT 25

G-7
PC BOARD ASSEMBLY - MAIN INVERTER BOARD

ELECTRICAL DIAGRAMS

G-7

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not available from Lincoln Electric. This information is pro-

vided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the
machine.

PRO-CUT 25

G-8
PC BOARD ASSEMBLY - INPUT BOARD

ELECTRICAL DIAGRAMS

G-8

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not available from Lincoln Electric. This information is pro-

vided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result in danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the
machine.

PRO-CUT 25

5%

75%

ELECTRODE SOL. ENERGIZED
(surface area is great)

Cup “O” rings must be good.
electrode is held to the
nozzle.

COMPRESSED AIR
INPUT

20%

VERY LITTLE
COMPRESSED

AIR FLOWING
at tip.

%= AIR FLOW

AIR IS FLOWING &
ELECTRODE SOL. IS “ON”.

HOLDS ELECTRODE TO NOZZLE

ELECTRODE SOL.
DE-ENERGIZED

COMPRESSED AIR
INPUT

PILOT & CUTTING

COMPRESSED AIR FLOW

CHAMBER FULL OF
COMPRESSED AIR

VENT

VENT

Spring is compressed

Spring is relaxed
helping the push

Lift start type feature during pilot

Air pressure pushes back
electrode creating a “LIFT”
start feature inside the
nozzle for a pilot arc

Air Flowing & Torch Solenoid is

“OFF”

1. No Compressed air flowing

2. Air is flowing & torch solenoid is
“ON”

PILOT CURRENT PATH

CUTTING CURRENT PATH

AIR TUBE (COPPER)

NOZZLE

ELECTRODE

BRASS CONDUCTOR
WITH A VENT

CURRENT PATH THROUGH TORCH

through plasma arc and yellow color parts

work

G-9
PC 25 TORCH DETAILS

ELECTRICAL DIAGRAMS

G-9

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.

PRO-CUT 25

SVM ERROR REPORTING FORM

We need to know if there are errors in our manuals. We also value any suggestions as to
additional tests or procedures that would make this SVM a better tool for you.

If you discover new or different “Problems or Symptoms” that are not covered in the three col­umn troubleshooting chart, please share this information with us. Please include the
machine’s code number and how the problem was resolved.

Thank You,
Technical Services Group
Lincoln Electric Co.
22801 St. Clair Ave.
Cleveland, Ohio 44117-1199

FAX [phone]

SVM Number ___________________________
Page Number if necessary__________________
Your Company__________________________
Your Name_____________________________

Please give detailed description below:
___________________________________________________________________________

___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________

SD287 04/06

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