ESAB Heliarc 350 AC/DC Welding Power Source Troubleshooting instruction

INSTRUCTION MANUAL

Heliarc 350 AC/DC

WELDING POWER SOURCE

F-14-447-A
April, 1995

This manual provides installation and operation instructions for the following Heliarc 350 AC/DC power sources:

ESAB P/N 35588 - 208/230/460 V ac, 1 phase, 60 Hz with power factor
ESAB P/N 35534 - 230/460/575 V ac, 1 phase, 60 Hz with power factor (refer to supplement F-14-453)
ESAB P/N 35597 - 220/380/415 V ac, 1 phase, 50 Hz with power factor (refer to supplement F-14-454)
L-TEC P/N 35600 - 220/380/415 V ac, 1 phase, 50 Hz with power factor (refer to supplement F-14-454)
ESAB P/N 35585 - 208/230/460 V ac, 1 phase, 60 Hz without power factor
ESAB P/N 35591 - 230/460/575 V ac, 1 phase, 60 Hz without power factor (refer to supplement F-14-453)

This manual is also suitable for use with L-TEC Heliarc 306 as made prior to April, 1995.

These INSTRUCTIONS are for experienced operators. If you are not fully familiar with the principles of operation and
safe practices for electric welding equipment, we urge you to read our booklet, "Precautions and Safe Practices for Arc
Welding, Cutting, and Gouging," Form 52-529. Do NOT permit untrained persons to install, operate, or maintain this
equipment. Do NOT attempt to install or operate this equipment until you have read and fully understand these
instructions. If you do not fully understand these instructions, contact your supplier for further information. Be sure
to read the Safety Precautions before installing or operating this equipment.

Be sure this information reaches the operator.

You can get extra copies through your supplier.

ESAB Welding &

Cutting Products

USER RESPONSIBILITY

This equipment will perform in conformity with the description thereof contained in this manual and accompanying
labels and/or inserts when installed, operated, maintained and repaired in accordance with the instructions
provided. This equipment must be checked periodically. Defective equipment should not be used. Parts that are
broken, missing, worn, distorted or contaminated should be replaced immediately. Should such repair or replace­ment become necessary, the manufacturer recommends that a telephone or written request for service advice be
made to the Authorized Distributor from whom purchased.

This equipment or any of its parts should not be altered without the prior written approval of the manufacturer.
The user of this equipment shall have the sole responsibility for any malfunction which results from improper use,
faulty maintenance, damage, improper repair or alteration by anyone other than the manufacturer or a service
facility designated by the manufacturer.

2

SAFETY PRECAUTIONS

WARNING: These Safety Precautions are for

your protection. They summarize precaution­ary information from the references listed in

Additional Safety Information section. Before
performing any installation or operating procedures, be sure
to read and follow the safety precautions listed below as well
as all other manuals, material safety data sheets, labels, etc.
Failure to observe Safety Precautions can result in injury or
death.

PROTECT YOURSELF AND OTHERS

Some welding, cutting, and gouging

-

processes are noisy and require ear
protection. The arc, like the sun, emits

ultraviolet (UV) and other radiation
and can injure skin and eyes. Hot metal can cause
burns. Training in the proper use of the processes and
equipment is essential to prevent accidents. Therefore:

1. Always wear safety glasses with side shields in any work

area, even if welding helmets, face shields, and goggles
are also required.

2. Use a face shield fitted with the correct filter and cover

plates to protect your eyes, face, neck, and ears from
sparks and rays of the arc when operating or observing
operations. WARN bystanders not to watch the arc and
not to expose themselves to the rays of the electric-arc
or hot metal.

3. Wear flameproof gauntlet type gloves, heavy long-sleeve

shirt, cuffless trousers, high-topped shoes, and a welding
helmet or cap for hair protection, to protect against arc
rays and hot sparks or hot metal. A flameproof apron may
also be desirable as protection against radiated heat and
sparks.

4. Hot sparks or metal can lodge in rolled up sleeves,

trouser cuffs, or pockets. Sleeves and collars should be
kept buttoned, and open pockets eliminated from the
front of clothing

5. Protect other personnel from arc rays and hot sparks with

a suitable non-flammable partition or curtains.

6. Use goggles over safety glasses when chipping slag or

grinding. Chipped slag may be hot and can fly far.
Bystanders should also wear goggles over safety glasses.

FIRES AND EXPLOSIONS -- Heat from
flames and arcs can start fires. Hot
slag or sparks can also cause fires and
explosions. Therefore:

1. Remove all combustible materials well away from the

work area or cover the materials with a protective non­flammable covering. Combustible materials include wood,
cloth, sawdust, liquid and gas fuels, solvents, paints and
coatings, paper, etc.

2. Hot sparks or hot metal can fall through cracks or

crevices in floors or wall openings and cause a hidden
smoldering fire or fires on the floor below. Make certain
that such openings are protected from hot sparks and
metal.“

3. Do not weld, cut or perform other hot work until the

workpiece has been completely cleaned so that there are
no substances on the workpiece which might produce
flammable or toxic vapors. Do not do hot work on closed

containers. They may explode.

4. Have fire extinguishing equipment handy for instant use,
such as a garden hose, water pail, sand bucket, or
portable fire extinguisher. Be sure you are trained in its
use.

5. Do not use equipment beyond its ratings. For example,
overloaded welding cable can overheat and create a fire
hazard.

6. After completing operations, inspect the work area to

-

make certain there are no hot sparks or hot metal which
could cause a later fire. Use fire watchers when neces­sary.

7. For additional information, refer to NFPA Standard 51B,

"Fire Prevention in Use of Cutting and
Welding Processes", available from the
National Fire Protection Association,
Batterymarch Park, Quincy, MA 02269.

ELECTRICAL SHOCK -- Contact can
cause severe injury or death. DO NOT use AC output in
damp areas, if movement is confined, or if danger of
falling exists. Put on dry, hole-free gloves before turn­ing on the power. Also:

1. Be sure the power source frame (chassis) is connected

to the ground system of the input power.

2. Connect the workpiece to a good electrical ground.

3. Connect the work cable to the workpiece. A poor or

missing connection can expose the operator or others to
a fatal shock.

4. Use well-maintained equipment. Replace worn or dam-

aged cables.

5. Keep everything dry, including clothing, work area, cables,

torch/electrode holder and power source. Fix water leaks
immediately.

6. Make sure that you are well insulated, especially when

standing on metal or working in tight quarters or in a damp
area. Wear rubber-soled shoes and stand on a dry board
or insulating platform.

7. Turn off the power before re­moving your gloves.

8. Refer to ANSI/ASC Standard
Z49.1 (see listing below) for specific
grounding recommendations. Do not
mistake the work lead for a ground
cable.

ELECTRIC AND MAGNETIC FIELDS — May be danger­ous. Electric current flowing through any conductor
causes localized Electric and Magnetic Fields (EMF).
Welding and cutting current creates EMF around weld­ing cables and welding machines. Therefore:

1. Welders having pacemakers should consult their physi-

cian before welding. EMF may interfere with some pace­makers.

2. Exposure to EMF may have other health effects which

are unknown.

3. Welders should use the following procedures to minimize

exposure to EMF:

3

A. Route the electrode and work cables together. Secure

them with tape when possible.
B. Never coil the torch or work cable around your body.
C. Do not place your body between the torch and work

cables. Route cables on the same side of your body.
D. Connect the work cable to the workpiece as close as

possible to the area being welded.
E. Keep welding power source and cables as far away

from your body as possible.

FUMES AND GASES -- Fumes and
gases, can cause discomfort or harm,
particularly in confined spaces. Do
not breathe fumes and gases. Shield­ing gases can cause asphyxiation.
Therefore:

1. Always provide adequate ventilation in the work area by
natural or mechanical means. Do not weld, cut, or gouge
on materials such as galvanized steel, stainless steel,
copper, zinc, lead, beryllium, or cadmium unless positive
mechanical ventilation is provided. Do not breathe fumes
from these materials.

2. Do not operate near degreasing and spraying opera­tions. The heat or arc rays can react with chlorinated
hydrocarbon vapors to form phosgene, a highly toxic
gas, and other irritant gases.

3. If you develop momentary eye, nose, or throat irritation
while operating, this is an indication that ventilation is not
adequate. Stop work and take necessary steps to im­prove ventilation in the work area. Do not continue to
operate if physical discomfort persists.

4. Refer to ANSI/ASC Standard Z49.1 (see listing below) for
specific ventilation recommendations.

CYLINDER HANDLING -- Cylinders, if
mishandled, can rupture and violently
release gas. Sudden rupture of cylin­der, valve, or relief device can injure or
kill. Therefore:

1. Use the proper gas for the process and use the proper
pressure reducing regulator designed to operate from
the compressed gas cylinder. Do not use adaptors.
Maintain hoses and fittings in good condition. Follow
manufacturer's operating instructions for mounting regu­lator to a compressed gas cylinder.

2. Always secure cylinders in an upright position by chain or
strap to suitable hand trucks, undercarriages, benches,
walls, post, or racks. Never secure cylinders to work
tables or fixtures where they may become part of an
electrical circuit.

3. When not in use, keep cylinder valves closed. Have valve
protection cap in place if regulator is not connected.

Secure and move cylinders by using suitable
hand trucks. Avoid rough handling of cylinders.

4. Locate cylinders away from heat, sparks,
and flames. Never strike an arc on a cylinder.

5. For additional information, refer to CGA
Standard P-1, "Precautions for Safe Handling of Com­pressed Gases in Cylinders", which is available from
Compressed Gas Association, 1235 Jefferson Davis
Highway, Arlington, VA 22202.

EQUIPMENT MAINTENANCE -- Faulty or
improperly maintained equipment can cause
injury or death. Therefore:

4

1. Always have qualified personnel perform the installation,
troubleshooting, and maintenance work. Do not perform
any electrical work unless you are qualified to perform
such work.

2. Before performing any maintenance work inside a power
source, disconnect the power source from the incoming
electrical power.

3. Maintain cables, grounding wire, connections, power
cord, and power supply in safe working order. Do not
operate any equipment in faulty condition.

4. Do not abuse any equipment or accessories. Keep
equipment away from heat sources such as furnaces,
wet conditions such as water puddles, oil or grease,
corrosive atmospheres and inclement weather.

5. Keep all safety devices and cabinet covers in position and
in good repair.

6. Use equipment only for its intended purpose. Do not
modify it in any manner.

ADDITIONAL SAFETY INFORMATION -- For
more information on safe practices for elec­tric arc welding and cutting equipment, ask
your supplier for a copy of "Precautions
and Safe Practices for Arc Welding, Cutting
and Gouging", Form 52-529.

The following publications, which are available from the
American Welding Society, 550 N.W. LeJuene Road, Mi­ami, FL 33126, are recommended to you:

1. ANSI/ASC Z49.1 - "Safety in Welding and Cutting"

2. AWS C5.1 - "Recommended Practices for Plasma Arc
Welding"

3. AWS C5.2 - "Recommended Practices for Plasma Arc
Cutting"

4. AWS C5.3 - "Recommended Practices for Air Carbon Arc
Gouging and Cutting"

5. AWS C5.5 - "Recommended Practices for Gas Tungsten
Arc Welding“

6. AWS C5.6 - "Recommended Practices for Gas Metal Arc
Welding"“

7. AWS SP - "Safe Practices" - Reprint, Welding Handbook.

8. ANSI/AWS F4.1, "Recommended Safe Practices for
Welding and Cutting of Containers That Have Held
Hazardous Substances."

This symbol appearing throughout this
manual means Attention! Be Alert! Your

safety is involved.

The following definitions apply to DANGER, WARNING,
CAUTION found throughout this manual:

Used to call attention to immediate haz­ards which, if not avoided, will result in
immediate, serious personal injury or
loss of life.

Used to call attention to potential haz­ards which could result in personal injury
or loss of life.

Used to call attention to hazards which
could result in minor personal injury.

SECTION 1 DESCRIPTION

1.1 GENERAL

The Heliarc 350 AC/DC Welding Power Source is a
constant current AC/DC welding power source designed
for high quality tig and stick welding in both the AC and
DC mode. The unique characteristics of the magnetic
and solid state circuits provide excellent arc conditions
for all tig welding as well as high alloy stick electrodes.
The non-saturating current limiting reactor and electronic
feedback control prohibits high current surges inherent
with saturable reactors or solid state SCR control alone,
therefore reducing spatter on stick electrodes as well as
tungsten spitting when tig welding. The electronic firing
circuit utilizes a voltage compensating circuit which com­pensates for line voltage variations of ±10 percent.

Through its unique design, the Heliarc 350 AC/DC com­bines all of the latest state-of-the-art magnetic and solid
state concepts to provide the wide range(s) volt-ampere
curve characteristics needed for a constant current AC/
DC power source - see Figure 1-1.

1.2 DUTY CYCLE

Duty cycle is defined as the ratio of load time to the total
time. Standard current ratings are based on a 10-minute
cycle. This machine is rated at 60 percent duty cycle
which means the rated load (300 amps) is applied for a
total of 6 minutes and shut off for a total of 4 minutes in
a 10-minute period. However, if the welding current is
decreased, the duty cycle can be increased. Conversely,
if the welding current is increased, the duty cycle must be
decreased. Figure 1-2 enables the operator to determine
the safe output of the power source at various duty
cycles.

Table 1-1. Specifications

NEMA †Rated Output @
60% Duty Cycle

Open Circuit Voltage 79 V ac/72 V dc

Output
Current
Range In
Amperes

Input Voltage 208/230/460 V ac

Input Current @
Rated Load in
Amperes**

Power Factor
@ Rated Load

Welding Current AC/DC

Low Range
High Range

Voltage 208 230 460

w/o P.F.C.*
with P.F.C.*

w/o P.F.C.*
with P.F.C.*

Auxiliary Power Output

Dimensions: Width

Weight Approx. 600 lbs 270 kg

*P.F.C. (Power Factor Correction)
†Output Rating conforms to NEMA Rating EWI-1971 Class 1 (60).
‡3-amp. minimum with LOW AMP KIT, DC only.
**These are NEMA ratings and in some cases, the input currents will vary --

Depth
Height

300 Amps @ 32 Volts
AC/DC, Tig/Stick

5‡ to 50 Amps
20 to 380 Amps

1 Ph, 60 Hz

12399112

86

Approx. 71%
Approx. 88%

115 V ac, 15 Amp, 60
Hz

22-3/4 in. 578 mm
32 in. 813 mm
36 in. 914 mm

56
43

Figure 1-1. Volt-Ampere Curves

Figure 1-2. Duty Cycle Chart

For DC & AC Balanced Wave Only

5

SECTION 1 DESCRIPTION

SECTION 2 INSTALLATION

2.1 GENERAL

Proper installation can contribute materially to the satis­factory and troublefree operation of the power source. It
is suggested that each step in this section be studied
carefully and followed as closely as possible.

2.2 UNPACKING AND PLACEMENT

A. Immediately upon receipt of the power source, it

should be inspected for damage which may have
occurred in transit. Notify the carrier of any defects
or damage at once.

B. After removing the power source from the shipping

container, check the container for any loose parts.
Remove all packing materials.

C. Check air passages at front, bottom and rear of

cabinet for any packing materials that may obstruct
air flow through the power source.

D. If the machine is not to be installed immediately,

store it in a clean, dry, well-ventilated area.

E. The location of the welding machine should be

carefully selected to ensure satisfactory and de­pendable service. Using the lifting eyebolt, or a
forklift truck, place the power source in the desired
location. Choose a location relatively close to a

properly fused source of electrical power. Never lift

the unit with cylinder attached.

F. The machine components are maintained at proper

operating temperatures by forced air which is drawn
through the cabinet by the fan unit on the rear panel.

2.3 PRIMARY (INPUT) ELECTRICAL
CONNECTIONS

This welding power source is a single-phase unit and
must be connected to a single-phase power supply.
Although designed with line voltage compensation, it is
suggested the unit be operated on a separate circuit to
assure that the performance of the machine is not
impaired due to an overloaded circuit.

ELECTRIC SHOCK CAN KILL! Do not touch electri­cally live parts. Be sure that all power is off by
opening the line (wall) disconnect switch when
primary electrical connections are made to the power
source. To be doubly safe, check your input leads
with a voltmeter to make sure that all power is OFF.

A. A line (wall) disconnect switch, with fuses or circuit

breakers, should be provided at the main power
panel (see Figure 2-2). The primary power input
must have three insulated copper conductors (two
power leads and one ground wire). The wires may be
heavy rubber-covered cable, or may be run in a solid
or flexible conduit. Refer to table 2-1 for recom-

mended input conductors and line fuse sizes. Do

not connect the input conductors until step C.

Table 2-1. Recommended Sizes for

Input Conductors and Line Fuses

Input Requirements

Amp e re s

Volts

c d

Input & Gnd.

Conductor*

CU/AWG

Time-Delay

Fuse Size

Amps

The power source is designed to operate at up to 40 °C
(104 °F) ambient temperature. For this reason, locate
the machine in an open area where air can circulate freely
at front, bottom and rear openings Leave at least 2 feet
of clearance between the rear of the power source and
wall or other obstruction.

IMPORTANT

Do not use filters on this unit. Output ratings are
designed and based on an unobstructed supply of
"clean" cooling air drawn over its internal compo­nents. If cooling air is dirty (e.g., laden w/conductive
dust), the interior should be cleaned using low
pressure air (refer to Section 4).

6

Units Without Power Factor Correction.

208
230
460

Units With Power Factor Correction.

208
230
460

c

DC and AC balanced wave input current rating.

123
112
56

99
86
43

184
166
83

137
124
62

No. 1/0
No. 1
No. 6

No. 2
No. 3
No. 6

200
175
100

150
150
70

dAC unbalanced wave input current rating.

*Sized per National Electric Code for 75 °C rated conductors @ 30 °C
ambient using a 60-percent duty cycle based on the AC unbalanced wave
ampere ratings. Not more than three conductors in the raceway or cable.
Local codes should be followed if they specify sizes other than those

listed above.

SECTION 2 INST ALLATION

B. For access to input terminal board, remove the

screws which secure the right side panel of the power
source. The input terminal board, Figure 2-1, is
clearly marked to show the available primary voltage
connections which may be used. Set the voltage
links on this board to match your actual incoming
voltage (208, 230, or 460 volt single-phase). As
shipped from the factory, the input terminal board
voltage links are set up for 460 volt operation.

C. Thread the input conductor cables from the wall

disconnect switch through the strain relief hole in the
rear panel (see Fig. 2-2). Secure the cables with the
strain relief coupling provided, and then connect
conductors to terminals L1 and L2 (on the input
terminal board) using UL listed pressure wire con­nectors. Connect the ground wire to the grounding
stud provided on the chassis base near the input
terminal board.

It is of the utmost importance that the chassis be
connected to an approved electrical ground to pre­vent accidental shocking. Take care not to connect
the ground wire to any of the primary leads.

2.4 EXTERNAL POWER/CONTROL HOSE
CONNECTIONS

Verify that all electrical connections comply with
local electrical codes and especially with require­ments established in booklet F-11-831 "High Fre­quency Stabilized Arc Welding Equipment", which
is packed with the power source.

Refer to Figure 2-2, for typical primary input, secondary
output, process gas and water, and torch connections
that are required for this unit's welding applications.

Before making any connections to the power source's
output terminals, make sure that all primary input
power to the power source is deenergized (off) at the
customer's disconnect switch.

The proper operation of the power source depends to a
great extent on the use of output cables that are insulated
copper, adequately sized, in good condition and properly
connected to the machine using UL listed pressure wire
connectors It is recommended that the output cables be
kept short as possible (this is particularly important for tig
applications using ACHF) and be of adequate current
carrying capacity. The resistance of the output cables
and connections cause a voltage drop which is added to
the voltage of the arc. Excessive cable resistance may
result in overloading as well as reducing the maximum
current output of which the power source is capable. The
welding output terminals are located on the front panel.
Table 2-2 will prove useful for selecting the recom­mended output cable size.

Figure 2-1. Input Terminal Board

D. Recheck all connections to make sure that they are

tight, well insulated, and that the proper connection
has been made.

Table 2-2. Recommended Welding Cable Sizes

Welding Total Length (Feet) of Cable in Weld Circuit*

Curren 50 100 150 200 250

200
250
300

*Total cable length includes work and electrode cables. Cable size is based on
direct current, insulated copper conductors, 60-percent duty cycle and a voltage
drop of 4 or less volts. The welding cable insulation must have a voltage rating
that is high enough to withstand the open circuit voltage of the machine.

2
1

1/0

2
1

1/0

1
1

1/0

1
1/0
2/0

1/0
1/0
3/0

7

SECTION 2 INSTALLATION

2.5 INSTALLATION OF OPTIONAL KITS

For installation of optional kits (if applicable) refer to
Section 2.6.

2.6 ACCESSORIES

A. Slope/Spotweld Control Module, P/N 680665.

The slope control features provide smoothly con­trolled welding starts and precise crater-free finishes
for critical manual tig welding applications; and the
spot-weld control features permit precisely timed
full-range spotwelding capability. For additional con­trol function information, refer to operation section.
This control module is completely self-contained and
is designed for easy plug-in, bolt-on installation on
the left-side of the front panel (see parts illustrations
and wiring diagrams in this manual, and for installa­tion instructions, see F-14-396A).

B. Analog Meter Module, P/N 680628. The voltmeter

and ammeter provide direct accurate indication of
AC and DC open-circuit and welding voltage, and
welding current The meter module is completely
self-contained and is designed for easy plug-in, bolt­on installation in the upper-left corner of the power
source front panel (see parts illustrations and wiring
diagrams in this manual, and for installation instruc­tions, see F-14-395).

C. Power Factor Correction Kit, P/N 680632. When

installed in units without power factor correction, it
provides lower input current draw. The kit consists
of 3 prewired power factor capacitors that are mounted
on the left-rear chassis base of the unit (see parts
illustrations and wiring diagram in this manual, and
for installation instructions, see F-14-394).

D. Low Amp Kit (For DC Only), P/N 680631. This kit

is designed to enhance arc starting and arc stability
down to 3 amps for low range DC tig welding of thin-

gauge materials. Even lower weld currents, down

to 2 amps and lower, are attainable with this
option by readjusting a shunt lead "inside" the
power source -- see Section 4 for Shunt Adjust­ment procedures. The kit consists of an On-Off

switch and provision for a factory-supplied wire har­nessed amp-type receptacle (for connecting an ex­ternal optional "pulse control" and a thermally-pro­tected internal inductor. For installation procedures,
see booklet F-14-398.

IMPORTANT

This option (Item D.) cannot be installed if a panel­mounted Pulse option (Item E.1.) is installed be­cause they both use the same front-panel mounting
location; however, it can be installed if the external
Pulse Control option (Item E.2.) is used.

E. Pulse Control Module, P/N 680693. The Pulse

Control module "pulses" the power source output,
giving the operator more precise control over pen­etration, heat input and bead shape. This pulsing
output current results in high quality tig or tig/spot
welds requiring less operator skill. This module is
completely self-contained and is designed for easy
plug-in (to an internal receptacle provided in the
wiring harness), bolt-on installation in the same front­panel location as, but in place of the Low-Amp Kit
option. For installation instructions, see F-14-397;
for replacement parts, see this manual.

F. FC-4EHD Foot Switch Current and Contactor

Control, P/N 679662. This device provides the

operator with remote control of current and contactor
operation at the welding station. Interconnection of
these functions to the main unit is provided by a pair
of mating 25-foot cable/plug assemblies. By de­pressing the foot pedal, the weld-start sequence
circuit will energize, and the welding current will
increase or decrease within the range preset on the
power source Current Control potentiometer.

G. TC-1A Torch Current and Contactor Control,

P/N 34718 (25-Ft Lg.). This remote fingertip control

is designed to be taped to any tig torch handle and it
allows the operator complete contactor control and
variable control of the welding current. The TC-1A
includes prewired current and contactor control plugs
which are compatible for use on ESAB solid-state
type, constant current power sources. The control
knob of this torch handle potentiometer/switch is
designed for right- and left-handed accessibility. By
simply rotating the knob clockwise (off of zero) the
intergral switch will energize the contactor, and fur­ther regulation (clockwise) will increase the output
current up to the limit preset on the power source
main control.

H. Torch Switch Assembly, P/N 674038. This device

is designed to be attached to any tig welding torch,
and provides the operator with remote contactor
operation at the welding station. Interconnection to
the power source is provided by its 12-1/2-ft cable/
plug assembly.

8

SECTION 2 INST ALLATION

Figure 2-2. Interconnection Diagram

9

SECTION 2 INSTALLATION

I. Current Hand Control, P/N 674209. This acces-

sory operates in series with the power source's 'main
current control' potentiometer to provide remote (up
to 25-ft) current regulation. The hand control
potentiometer's current adjustment is always con­trolled by and limited to the range that is preset on the
main current control.

J. WC-9 Coolant Circulator, P/N 33540, is used for

water cooled torch operation and is designed to be
"free standing" in a convenient location near the
torch. A four-gallon capacity tank provides 1.0 gal/
min @ 50 psi, using 6 amps, 115 volts, 60 Hertz, 1­phase input. Since the circulator is designed to run
continuously during a welding operation, never con­nect it to a power source that uses a solenoid
controlled water supply that opens and closes with
each operation of the welding contactor -- the cooling
efficiency of the unit will be hampered and the
starting winding in the pump motor may burn out.
Refer to Figure 2-2 for suggested hose hookup.

K. WC-8C Coolant Circulator, P/N 33739, is used for

water cooled torch operation and is designed to fit in
a cylinder rack of a power source truck (item M). A

1.5 gallon capacity tank provides 1 gal/min @ 50 psi,
using 6 amps, 115 volts, 60 Hertz, 1-phase input.
Since the cooler is designed to run continuously
during a welding operation, never connect it to a
power source that uses a solenoid controlled water
supply that opens or closes with each operation of
the welding contactor -- the cooling efficiency of the
unit will be hampered and the starting winding in the
pump motor may burn out. Refer to Figure 2-2 for
suggested water hose hookup.

L. TR-21 Truck, P/N 680794. Provides complete mo-

bility for power source or welding outfit and includes
a bracket for two gas cylinders or one gas cylinder
and a WC-8C water cooler.

M. Water Solenoid Valve Kit, P/N 30570. This kit

comes completely assembled and ready for mount­ing in place of the existing bulkhead fittings provided
for the WATER IN service on the rear panel of the
power source. It is identical to the gas assembly,
except that its hose adaptor connection is a left-hand
fitting (58V75). To install the solenoid assembly,
refer to instruction sheet F-14-452.

10

SECTION 2 INST ALLATION

SECTION 3 OPERATION

3.1 CONTROL FUNCTIONS

A. Power On-Off Switch (ROS). In the OFF position,

the power source is electrically shut down; however,
input voltage is still present in the unit (at the input
terminal board and the Power On-Off switch) -­unless the customer's line switch is off. In the ON
position, this switch provides power to the fan motor,
the primary and secondary of the main transformer
and its 115-volt and 24-volt windings to energize the
control circuitry by preparing the ready-to-weld sta­tus of the unit, as determined by the positioning of the
Tig-Stick switch SW1 (see Item B. following).

B. Tig-Stick Mode Switch (SW1). This two-position

toggle switch sets the operational modes which can

be used. In the STICK position (and the ROS

toggle is ON), the solid-state contactor and arc-force
circuits immediately energize and welding power is

continuously present at the output terminals. In the
TIG position, the solid-state contactor and other tig

sequencing circuits are controlled by a remote de­vice (foot or torch switch) through the Remote
Contactor Receptacle J4 (see Item C. following).

Amps. The Low Range provides exceptional clean­ing action for all low current tig AC applications. For
higher current tig welding, always try to select the
appropriate minimum current range that adequately
covers your welding requirements. For stick elec­trode welding, position the switch to the desired

current output range. Do not change the position

of this switch while welding or under load.

NOTE

The Min/Max current values for the Low/High ranges
can be shifted even lower by readjusting the shunt

-- see Section 4 for procedures.

F. Current Control Potentiometer (R44). This poten-

tiometer (an integral part of SCR Control p.c. bd.)
provides fine adjustment of welding current within
the range selected on the Current Range Switch
(SW1). The panel-faced dial provides an accurate
reference for resetting and/or adjusting the potenti­ometer.

NOTE

In the Tig Mode, the Arc Force control/circuitry is
inoperable.

C. Remote Contactor Receptacle (J4). The cable

connector from the remote Foot Control or Torch
Switch accessories plugs into this low-voltage recep­tacle to control the conducting sequence of the
bridge SCRs to make or break the tig welding output
power.

D. Current Selector Switch (CSS). A 3-position switch

offers a choice of AC, DCSP, or DCRP output current
to suit your particular welding applications. Placing
the switch in its DCSP mode causes the output
terminals to assume the following polarities; work is
positive, and torch/electrode is negative. Conversely,
when the switch is in DCRP: work is negative and

torch/electrode is positive. Do not change the

position of this switch while welding or under
load.

E. Current Range Selector Switch (SW1). This 2-

position switch (an integral part of the SCR Control
p.c. bd.) permits quick coarse selection of the output
current ranges which can be used. The current
ranges are marked Low 3-50 Amps and High 20-380

G. Current Panel-Remote Switch (SW2), and Re-

mote Current Control Receptacle (J3). This two-

position toggle switch determines the location from
which welding current will be operated either from the
power source potentiometer -- PANEL position, or,
from REMOTE location by plugging an optional
FC-4EHD Foot or TC-1A Torch Control into Recep­tacle J3. When the Remote position is selected, the
remote control options will vary the welding current,
but only within the range preset on the power source
Current Control Potentiometer (R44).

H. Post Flow Control (PFP). This potentiometer (an

integral part of the Logic p.c. bd.) provides a time
(from 3 to 45 seconds) post-flow of shielding gas and
cooling water after the contactor signal is opened.

I. High Frequency (and Gas Water Solenoids) Se-

lector Switch (HFS). A three position toggle switch

(an integral part of the Logic p.c. bd.) controls high
frequency and, shielding gas and cooling water in the
welding operation.

The functional positions are: Off -- no high frequency

and, gas and water solenoid valves are deenergized
(this is the normal position for all stick welding);

Continuous -- high frequency and, shielding gas

and cooling water (if used) are provided throughout
the entire welding cycle (this is the normal position for

all AC tig welding); and, Start -- high frequency

11

SECTION 3 OPERATION

U

initiates immediately and cuts off when the arc is
established, gas and water solenoids energize and
remain on throughout the welding cycle (this last
position is normal for most DC tig welding applica­tions).

J. High Frequency Intensity Control (HFI). This

rheostat, with panel-faced dial, allows you to regu­late the output intensity of the high frequency oscil­lator circuit. For most applications the control should
be set at maximum.

K. Gas and Water Torch Connections.

1. Three service connectors are located on the lower­right side of the rear panel. The upper fitting is
equipped with a solenoid valve and provides GAS IN
service that is threaded to accept a standard CGA
"B" size "right-hand" inert gas hose connection nut.
The remaining two fittings provide torch cooling
water IN and OUT service that are threaded to
accept standard CGA "B" size "left-hand" water hose
connection nuts. As shipped from the factory, the
WATER IN fitting is not equipped with a solenoid
valve (available as a field-installed option, see II-D-

13); and therefore if water-cooled torch operation is
required, the water service should only be used with
a coolant circulator or a continuous water supply (see
Fig. 4).

2. The three torch service connectors (from K-1) are
located on the lower left-hand side of the front panel
(behind the protective cover). Two of these connec­tors, WATER DRAIN and shielding GAS fittings, are
electrically connected to the TORCH output block -

- which makes these fittings "power" as well as
"service" connections to the torch (see Fig. 4). The
remaining connector, WATER-TO-TORCH, provides
this service when water cooled torch operation is
used.

M. Arc Force Potentiometer (AFP). This control is

only functional in the Stick mode, and is marked MIN,
1-9, MAX. The lower settings provide less short
circuit current and a softer, more stable arc. The
higher settings provide more short circuit current and
a forceful, more penetrating arc. For most stick
welding, set the knob at 3 or 4 and readjust up
(forceful) or down (softer) as desired. Note that with
the knob in the MIN. position a longer arc length can
be maintained, and at MAX., the arc will extinguish
much easier when drawing away from the work.

N. Slope/Spotweld Control Module. This module

operates as follows:

1. The Slope features consist of the following
functional controls:

a. On-Off Slope Switch places the slope con-

trol features in or out of the conventional tig
welding circuit.

O

G

SELH

I

R

B

M

D

J

F

N

P

A

C

G

K

I. Soft Start Switch (SW1). This two-position switch

(an integral part of the soft start p.c. bd.) allows you
to reduce the initial high current overshoot when

starting a welding arc above 30 amperes -- below

30 amperes, the unit is inherently soft-starting. In the
OFF position, full current is applied the instant the arc
is struck and this is the normal position for all stick,
tig-slope and tig-spot welding. In the SOFT START
position, initial welding current is less than that set by
the power source Current Control potentiometer.
Once the arc is established, it has no effect on the
full-load current setting.

12

WELDING OUTPUT CONNECTIONS

NDER COVER

b. Up Slope Potentiometer allows you to set a

timed period which provides a gradual cur­rent increase (upslope) at the beginning of a
weld for smoother starts and elimination of
blow holes. The up slope time control can be
adjusted to provide an upslope time from 0
to 10 seconds (Min to Max). With the pot set
at Min, the current will rapidly rise from the
minimum of the selected "current range" up
to the actual setting established on the "cur­rent control" potentiometer. As the upslope

SECTION 3 OPERATION

pot is increased toward Max, the current will
take longer to rise (in direct proportion to its
time setting) until the desired weld current is
reached.

c. Down Slope Potentiometer allows you to set

a timed period which provides a gradual
current decrease (downslope) at the end of
the weld cycle for crater-free finishes. The
Down Slope time control can be adjusted to
provide a downslope time of 0-10 seconds
(Min to Max). The setting of this control is
similar to that of the Up Slope feature, ex­cept the Down Slope setting determines the
rate at which welding current will gradually

decrease down to the minimum of the
selected "current range" or as determined

by the Final Current "cut off level."

d. Set the 3-position "Spotweld-Off-Final Cur-

rent" switch to the FINAL CURRENT posi­tion when slope control is used. This mode
enables the Final Current time potentiom­eter to set the current cut-off-level during a
downslope period.

spotweld timer for use in the Tig welding
sequence. With the switch in its OFF posi­tion, the "timed-welding" feature is
deenergized and welding action is conven­tionally controlled from the torch switch.

b. Spotweld Timer Potentiometer is provided

to control the period of time weld power is
available during tig Spotwelding operations.
The spotweld pot can be adjusted to provide
arc duration periods from 0 to 10 seconds
(Min to Max). The operating sequence
begins when the torch switch is closed and
the arc is initiated. As soon as the arc is
established, the timer begins timing out.

The torch switch must be held closed
throughout the entire welding interval.

After the spotweld time cycle is completed,
the welding current cuts off and when the
torch switch is released, the time will recycle
and the post flow sequence will begin. If for
any reason you wish to prematurely termi­nate the spot weld, simply release the torch
switch and all welding action will stop except
post flow.

When the "Final Current" switch position is selected
("on"), the solid state contactor and welding output
will remain "on" for the length of time set on the Final
Current potentiometer -- after the torch switch has
been released/deenergized (to initiate the downslope
sequence).

e. Final Current Potentiometer allows you to

set a timed period from 0 to 10 seconds (HI
to LOW) that determines the "cut-off-level"
of welding current at which the contactor will
drop out, after the torch switch is released,
during downslope. The pot can be set to
drop out slightly below the welding current
level (HI setting), or at the minimum output
of the selected current range (LOW setting).

2. The Spotweld features consist of the follow­ing functional controls:

a. The 3-position "Spotweld-Off-Final Current"

switch determines whether or not the
spotwelding sequence will be functional in
the Tig welding mode. Placing the switch in
the SPOTWELD position actuates the

NOTE

If the High Frequency switch is in its CONTINUOUS
position, the high frequency will remain "on" after
the spotweld (time) cycle is completed and until the
torch switch is released. If this is a problem, simply
change the High Frequency switch from "Continu­ous" to "Start" only -- even for AC welding opera­tions.

O. AC/DC Analog Meter Module. The optional meters

provide direct accurate reading of AC and DC open­circuit and welding voltages, and welding current.

P. This module location is designed to accept either of

two optional kits as follows:

1. Low-Amp Kit. This module is optional and

consists of a front panel On-Off switch and an
amp receptacle (for connecting an external Pulse
Control), and an internal thermally protected
inductor. It is designed to enhance arc starting
and stability for "low range" DC tig welding down
to 3 amperes. The duty cycle range of this
feature runs from 3 to 20 amperes @ 100% to a
maximum of 50 amperes @ 16%.

13

SECTION 3 OPERATION

2. Pulse Control. This module is optional and

consists of a front panel On-Off switch, a Back­ground Current pot, a pulse Frequency (cycles/
second) pot, and a pulse On Time (percent) pot.
It is designed to "pulse" the welding current to
provide greater control over penetration, heat
input and bead shape during the welding opera­tion.

R. Balance Control Feature. This component, a

potentiometer for the units, allows you to change the
"wave balance" characteristics of the Heliarc 350 as
follows:

These units incorporate a potentiometer to effect a

wave BALANCE change. With the potentiometer

set in its extreme counterclockwise or "Max.
Cleaning" position, the machine is set up for

"balanced" wave operation (equal portions of re­verse and straight polarity -- 50/50) for use in the
following applications; DC tig, DC Stick, AC Stick,
and AC tig w/Maximum Cleaning (and minimum
penetration)—this will be the normal (counterclock­wise) position for most applications. As the potenti­ometer is turned clockwise toward "Max. Penetra­tion," cleaning action will lessen and penetration will
increase until you reach Maximum Penetration and
this "unbalanced" wave output (more straight than
reverse polarity) should only be used for AC tig
applications when needed.

IMPORTANT

Please note that when using "Maximum Penetration
in AC tig," the machine will have a reduced duty
cycle. Also, when using DC tig or stick welding, the
controls should always be set to the Maximum
Cleaning or "balanced" wave position.

3.2 SEQUENCE OF OPERATION

Never, under any circumstances, operate the power
source without its panels in place. In addition to the
safety hazard, improper cooling may cause over­heating which will damage the internal components.
Also, make sure you are adequately protected be­fore you start welding -- welding helmet, gloves and
ear protection should always be worn.

A. STICK ELECTRODE WELDING

1. Connect all welding cables to workpiece and elec­trode holder as shown on the Interconnection Dia­gram, Figure 2-2.

2. Place the power source's Power On-Off, Soft Start,
Slope, Spotweld, Low Amp, and High Frequency
switches to their OFF positions. Set the Balance
control to its Maximum Cleaning (or balanced wave)
position and leave it there.

3. Close the main (wall) disconnect switch or circuit
breaker to provide input voltage to the power source.

4. Place the Current Selector switch to either AC,
DCSP, or DCRP depending on your welding applica­tion.

Do not change the position of this switch while
welding.

S. Front Panel 3-Amps Fuse (F1). This fuse provides

protection to the 24-volt control circuit and the printed
circuit boards.

T. Rear Panel Auxiliary 115-V. Receptacle (J2). This

duplex receptacle can be utilized to supply 115-volt
power for other equipment (water cooler, grinder,
etc.) and is protected by a 15-ampere circuit breaker.

14

5. Place the Tig-Stick toggle switch to its STICK posi­tion.

6. Place the Current Range Selector to one of the two
Current Range positions to suit your welding applica­tions.

Do not change the position of this switch while
welding.

7. Adjust the Current Control potentiometer for the
approximate desired welding current.

SECTION 3 OPERATION

8. Set the Arc Force control at Minimum on the dial and
readjust as necessary to provide a more forceful
welding arc.

9. Place the Current Panel-Remote switch in its PANEL
position.

10. Place the Power On-Off switch to its ON position.
This will immediately energize the power source up
to the output terminals and the electrode holder.
Commence welding by touch or scratch starting.

11. If necessary, readjust the Current Control potenti­ometer to obtain the exact welding condition re­quired.

B. TIG WELDING

1. General Procedures For Tig and Tig-Spot Weld­ing

a. Make the necessary welding power and service

connections as shown on the Interconnection
Diagram, Figure 2-2.

b. Depending on the control model purchased (De-

luxe or Basic) and options installed, set the
following switches in their OFF positions; High
Frequency, Slope, Spotweld, Soft-Start and Low­Amp Option.

c. Place the Tig/Stick Mode selector switch in TIG

position. Remember this mode requires that a
torch switch or foot control be plugged into the
Remote Contactor receptacle in order to make
and break the welding sequence.

NOTE

The Arc Force potentiometer is only used in the stick
mode, and is functionally out-of-the-circuit in the
Tig mode.

d. Close the main (wall) disconnect switch to pro-

vide single-phase power to the welding unit.

g. Place the Current Selector switch in either AC,

DCSP, or DCRP position. The AC position is
primarily used for welding of aluminum and
magnesium. The DCSP position will normally be
used to cover all of the remaining metals (steel,
copper, refractory, etc.) and alloys. The DCRP
position produces a shallow weld, which makes
it suitable for joining thin sheets of metal (e.g.,
aluminum, magnesium, foil, etc.).

Do not change the position of this switch while
welding.

h. Set the Balance control (potentiometer) to the

position which best suits your "AC-Tig" welding
condition -- Remember that when using "Maxi­mum Penetration" mode, your duty cycle (AC
welding arc time) must be reduced. Also remem­ber that for DC welding applications, this control
should always be set for "Maximum Cleaning."

i. Set the High Frequency selector switch to either

Continuous (AC) or START (DC). (If AC welding
at 50 amps or more, it may be placed in START
position.) Also see section III-I.

If high frequency is to be used, set the intensity
control as desired. If you have had no experi­ence on a particular application, set this control
at Maximum and readjust later to secure the
intensity which gives the best results.

j. Adjust the Current Control potentiometer for the

approximate welding current desired. Remem­ber that the setting placed on this control will be
the maximum usable current which can be regu­lated from a "remote" foot or hand control acces­sory, if used.

k. Select the proper tungsten electrode from Table

3-1 following:

e. Set the Power On-Off switch to On position. This

will start the fan motor and immediately energize
the unit up to its solid state contactor.

f. Set the Current Range Selector switch for the

desired output current -- LOW or HIGH. The
current limits within each range are printed on
the front panel. Always try to operate in the
lowest range which will adequately do the job.

15

SECTION 3 OPERATION

be provided either remote or locally from the
power source.)

Table 3-1.

Typical Current Ranges For Tungsten Electrodes

Welding Currents, Amps

Electrode
Diameter
Inches

0.020

0.040
1/16
3/32

1/8
5/32
3/16

1/4

ACHF DCSP DCRP
Using pure

tungsten
electrodes

5-15

10-60

50-100
100-160
150-210
200-275
250-350

---

Using
thoriated
electrode

5-20

15-80

70-150
140-235
225-325
300-400

---

---

Using pure or
thoriated tungsten
electrodes

5-20

15-80

70-150
150-250
250-400

---

---

---

---

--­10-20
15-30
25-40
40-55
55-80

80-125

l. Depending on the type of current regulation

desired, place the "Panel-Remote" Current Con­trol switch as follows:

(1) PANEL position -- only permits current regu-

lation to be made locally from the main
Current Control potentiometer and is the
normal position for all stick, all tig-spot, and
many conventional tig welding applications
which do not normally utilize the optional
Foot or Hand Control accessories.

(2) REMOTE position -- this permits current

regulation from a remote location (e.g., a

Foot or Hand Control), but only within the

range preset on the main current control
potentiometer.

m. Set the Post Flow potentiometer (PFP) to pro-

vide the desired time interval (from 4 to 45
seconds) of shielding gas and cooling water after
the welding arc has cut off.

2. Specific Procedures For Tig Welding

In addition to the general procedures covered in
Section IV-B-1 preceding (depending on the model
purchased), two additional operating features, Slope/
Spotweld and/or Low Amp Option, can also be used
in this sequence.

(1) If combined current and contactor control is

desired, connect the optional FC-4EHD Foot
Control or TC-1A Torch Control to the appro­priate receptacles on the power source and
make sure the Current Panel/Remote switch
is positioned for REMOTE operation. (Set
the main Current Control potentiometer to
the highest current to be used. Current can
now be regulated up to the preset limit by
depressing the foot pedal on the FC-4EHD
or turning the pot on the TC-1A and this
action will also energize the solid state
contactor.)

If you wish to use the FC-4EHD or TC-1A for
remote contactor operation only, make sure
the Current Panel/Remote switch is reposi­tioned to PANEL setting.

(2) If separate current control is desired, con-

nect the optional Current Hand Control to its
power source current receptacle and make
sure the Current Panel/Remote switch is in
REMOTE position. (The Hand Control will
vary welding current, but only within the
range preset on the main Current Control
potentiometer.)

(3) If remote contactor control only is desired,

use the optional Torch Switch accessory,
P/N 674038. (The torch switch must be held
closed during the entire welding cycle.)

b. The Soft Start switch can be set as desired. It is

intended to provide soft-starts for tig applications
about 30-amperes (below 30-amperes, the unit
is inherently soft starting); however, if hot starts
are desirable (above 30 amps), leave the switch

in its "off" position. This switch should gener-

ally be left in its OFF position for all tig-slope
and/or tig-spot welding.

c. If Slope Control is provided and is to be used, do

the following:

IMPORTANT

a. Remote Contactor and/or Current Control func-

tions are provided using one or more of the
following options.

(Note that contactor operation
thru a remote control device is absolutely essen­tial in the Tig mode; whereas, current control can

16

This "slope" feature should not be used with Soft
Start (Item b) "on." Make sure the Soft Start switch
is "off." Also, Current Control should be set and
controlled from the power source current control
pot; therefore, always set the Current Panel/Remote
switch in its PANEL position. Remote Contactor

SECTION 3 OPERATION

Control is normally provided using the optional
"torch switch" accessory; however, this can also be
accomplished using the FC-4EHD foot or TC-1A
torch control so long as their current control fea­tures are deenergized.

(1) Place the Slope On-Off switch in the On

position.

(2) Set the three-position "Spotweld-Off-Final

Current" switch to its FINAL CURRENT
position.

(3) Set the Up Slope to provide the timed cur-

rent rise desired (from 0 to 10 seconds). The
lower the setting, the more rapid the current
rise, conversely, the higher the setting, the
more gradual the rise to the selected weld
current setting.

(4) The Down Slope Control can be set to

provide a timed interval (0 to 10 seconds) at
which welding current will gradually decrease
to the minimum of the preselected ranges, or
to the setting determined by the Final Cur­rent "cut-off-level" control following.

(5) The Final Current control potentiometer sets

the timed period (0 to 10 seconds) that
determines the "cut-off-level" of welding
current at which the contactor will drop out,
after the torch switch is released, during
downslope. This control can be slightly
below the welding current level, (HI setting)
or at any level including that of the minimum
output of the preselected current range (LOW
setting).

When the "Final Current" switch position (item C-2)
is selected, the solid-state contactor and welding
output will remain "on" for the length of time set on
the Final Current potentiometer -- after the torch
switch has been released/deenergized (to initiate
the downslope sequence) or unless the Tig/Stick
switch is inadvertently placed in Stick.

d. If the optional Pulse Control is provided and

used, do the following:

IMPORTANT

In pulse welding operations, the Peak current is
always set and normally controlled from the power

source's main Current Control potentiometer, and
the Background current (on the module) is selected
as a percentage of the "peak" setting. This opera­tion can be setup for Panel or Remote current con­trol; however, if Remote Control is used, remember
that current regulation can only be varied within the
current range (and percentage) preset on the power
source. You must also be careful when varying the
pulsed welding current, that the background current
level does not drop below the recommended mini­mum for your specific electrode size, since this may
result in arc outages.

Contactor control is normally provided using the
remote torch switch accessory; however, this can
also be accomplished using the FC-4EHD foot or
TC-1A torch control accessories when the appropri­ate cables are connected to the power source.

(1) Set the Pulse module On-Off switch to its

ON position to activate the pulsing features.

(2) Set the power source Current Control poten-

tiometer to provide the desired "peak" cur-

rent desired for your operation -- be careful

that this setting does not exceed the
maximum current rating of your elec­trode.

(3) Set the Pulse module Background Current

potentiometer to provide the percentage of
"background" current desired. This pot is
calibrated in approximate percentages from
Minimum current output of the power source,
up to Max. (100%) of the power source's

"peak" current setting -- be careful that this

approximated setting does not drop be­low the minimum current rating of your
electrode, particularly if you're varying
the pulsed welding current from a re­mote control It may result in arc outages.

(4) Set the frequency control to provide the

number of pulses per second desired from

0.5 to 10 Hz.

(5) Set the On Time control to provide the

percent of time (5% to 95%) that the peak
current level will be "on," as compared to its
background current level. This setting, which
essentially sets the pulse width, is indepen­dent of the frequency control.

e. The Low Amp option, if provided and used, is

designed to enhance arc starting and arc stabil-

17

SECTION 3 OPERATION

ity for "low-range, d.c. tig" welding down to 3
amperes. This feature can be very beneficial for
welding very thin gauge materials. This option
would not normally be used in conjunction with

"slope" or "soft-start." Remember that this

switch also has a duty cycle which runs from
3 to 20 amperes @ 100%, to a maximum of 50
amperes @ 16%.

If you wish to lower this current range even
further (down to 2 amps and below), simply
readjust the shunt lead "inside" the power source
as described in Section V, Shunt Adjustment.

f. To establish the welding arc, position the torch

electrode near the workpiece (e.g., 1/8" typical)
and close the Remote Torch or Foot Control.
This will energize the solid state contactor and
provide high frequency to initiate the arc, and
upslope sequence (if provided).

g. If necessary, readjust the panel or remote Cur-

rent Control until you secure the exact condition
desired.

h. When welding is completed, release the remote

Torch Switch to initiate downslope sequence (if
provided and used) and weld finish After the arc
has extinguished, shielding gas and water will
continue for the time left in the Post Flow mode.
Since postflow is initiated when the torch switch
is released, it is necessary to set a high enough
Postflow time to cover downslope and the time
required to protect the cooling weldment.

3. Specific Procedures For Tig Spotweld - If pro­vided.

In addition to the general procedures covered in
Section IV-B-1 preceding, do the following for Tig
Spotwelding.

b. Soft Start would not normally be used for tig-

spot; therefore, place this switch in OFF posi­tion.

c. Low-Amp option (if provided) would not normally

be used for tig-spot; however, if desired, remem­ber, it can only be used in "low-range-d.c."
applications and it also has a duty cycle which
must be maintained -- see Section III-P.

d. The Slope mode selector switch should be placed

in the OFF position for Spotwelding.

e. If the optional Pulse Control is provided and is to

be used, set the controls in the same manner as
described in Section IV-B-2-d.

f. Set the Spotweld Selector switch to the ON

position.

g. Set the Spotweld Timer control for the desired

arc time interval (variable from 0 to 10 seconds).

h. Connect the optional Torch Switch to the Re-

mote Contactor receptacle.

i. Place the torch in position to spot weld and then

close the torch switch/trigger. (The switch must
be held closed during the welding cycle.) This
action initiates all programmed circuitry to ener­gize contactor and high frequency, start and cut­off the arc after the preselected time, and initiate
postflow service.

j. When the weld is completed, release the torch

switch and the Spotweld Timer will recycle and
ready the machine for another weld sequence.
(If or any reason you wish to prematurely termi­nate the spot weld, simply release the Torch
Switch and all welding action will stop.)

NOTE

Remote Current regulation is not recommended for
use in Tig Spotweld operation. Remote Contactor
control will normally be provided using the optional
Torch Switch.

a. Set the Current Control switch to its PANEL

position.

18

NOTE

If the High Frequency switch is in its CONTINUOUS
position, the high frequency will remain "on" after
the spotweld (time) cycle is completed and until the
torch switch is released. If this is a problem, simply
change the High Frequency switch from "Continu­ous" to "Start" only -- even for AC welding opera­tions.

SECTION 4 MAINTENANCE

4.1 GENERAL

If this equipment does not operate properly, stop work
immediately and investigate the cause of the malfunc­tion.

Be sure that the wall disconnect switch or circuit
breaker is open before attempting any inspection or
work on the inside of the power source. Always wear
safety goggles with side shields when blowing out
the unit with the low pressure air.

4.2 CLEANING

Since there are no moving parts (other than the fan) in the
power source, maintenance consists mainly of keeping
the interior of the cabinet clean. Periodically remove the
cover from the cabinet and blow accumulated dust and
dirt from the air passages and the interior components,
using clean low pressure air. It is imperative that the air
passages, to the interior of the unit, be kept free of dirt
accumulation to ensure adequate circulation of cooling
air, especially over the rectifier bridge plates and magnet­ics. The length of time between cleaning will depend on
the location of the unit, and the amount of dust in the
atmosphere.

4.3 LUBRICATION

Fan motors with oil tubes require lubrication after 1 year
of service. Motors without oil tubes are permanently
lubricated and do not require any attention.

wire from the slot and replace it on the other side of

the brown wire to complete the modification. Under

no circumstances should this machine be oper­ated "without" the green wire attached to the
shunt -- this would cause the machine to weld at
maximum output with no control.

B. Raising The Current Range without Low Amp Kit

Installed. In some cases you wish to raise the

specified maximum output above 380 amps for
higher range welding applications. This can be done
as follows:

To shift the current range upwards (meaning the
minimum and maximum current range will shift higher
than the original specification), simply move the
green wire in the shunt slot downward, and retighten.

If this is done, remember that the original duty
cycle of the machine does not change and must
not be exceeded -- see duty cycle chart in front
of booklet for approximate percentages.

4.5 SPARK GAP SERVICING &
ADJUSTMENT

The spark gap, which is part of the high frequency
generator, is factory set at 0.030-in. (+0.002-in.). After
extended operation or if erratic operation is noted, it may
be necessary to readjust or replace the electrodes
(673578). Use a feeler gauge when readjusting the gap.
(See Form 11-831, "Recommended Installation and Test
Procedures for High Frequency Stabilized Arc Welding
Machines," packed with the unit.) Cleaning or dressing
of the spark gap electrodes is not recommended. When
replacement is necessary, both electrodes should be
replaced.

4.4 SHUNT ADJUSTMENT

The 350's internal shunt lead can be readjusted to
provide additional benefits as follows:

A. Lowering Current Range With Opt. Low Amp Kit

Installed. The Low Amp Kit will allow you to weld

down to 3 amps for DC applications. However, if you
wish to weld even lower (down to 2 amps and below),
a simple wire adjustment on the internal brass shunt
can be made as follows:

To shift the current range down (meaning the mini­mum and maximum current range will shift lower
than the original specification), adjust the green wire
on the brass shunt upward in the slot and retighten.
In some cases, you may need to remove the green

Remember that high frequency radiation increases as
the gap increases and this can cause interference in
other electronic equipment.

A. Loosen retaining screw "A" only enough to free

electrode point "C" for adjustment.

B. Place feeler gauge of proper thickness between gap

"B."

C. Apply slight pressure against loosened electrode

point "C" so the feeler gauge is held firmly in the gap.
Tighten retaining screw "A."

19

SECTION 4 MAINTENANCE

When replacing defective diodes, make sure mount­ing surfaces are clean. Coat mounting surfaces with
Dow Corning No. 340 silicon heat sink compound, or
equivalent. Replaced diode (nuts) should be tight­ened only until firm, and then torque tight (recom­mended range is 275 inch lbs. min. to 325 inch lbs.
max.).

B. Silicon Controlled Rectifier - SCR.

Figure 4-1. Spark Gap Adjustment

4.6 TESTING AND REPLACING BRIDGE

ASSY. COMPONENTS

SCRs and silicon diodes are devices which allow current
to flow in only one direction, and block current in the other
direction. The SCRs and silicon diodes used in this
power source are designed to provide long troublefree
operation; however, should a failure occur, they may
require replacement. The testing procedures to deter­mine defective components follow:

A. Silicon Diode Rectifier, D1-D2.

Disconnect the power lead to the diode, to provide an
open circuit across the component to be tested.
Using an ohmmeter set to the Rx1 scale, check the
resistance in the forward and reverse direction. A
good diode will read high in reverse and low in the
forward direction.

Disconnect the SCR wiring (but do not unclamp) to
break continuity and provide an open-circuit across
the component to be tested. Using an ohmmeter set
to the Rx1 scale, check the resistance across the
SCR in both directions. A good SCR will read high in
both directions. If the reading is low or zero in either
direction, the SCR is defective.

When replacing defective SCRs, make sure the
mounting surfaces are clean. Coat the mounting
surfaces with Alcoa No. 2 electrical joint compound,
available from ESAB in 8 oz. containers under P/N

73585002. Make certain that the polarity on the
replacement SCR is the same as on the unit being
replaced. Place the top clamp piece over the bolts

and tighten each nut hard finger tight. The clamp

piece should be parallel to the top plate. Then tighten
each nut approx. 1/4 turn at a time (alternately), for
two complete revolutions until the force indicator on
the clamp assembly reads 1.0 kilo pounds (1000 lbs).

20

SECTION 5 TROUBLESHOOTING

5.1 GENERAL

If power source is operating improperly, the following
troubleshooting information may be used to locate the
source of the trouble.

Check the problem against the symptoms in the following
troubleshooting guide. The remedy may be quite simple.
If the cause cannot be quickly located, open up the unit
and perform a simple visual inspection of all the compo­nents and wiring. Check for secure terminal connections,
loose or burned wiring or components, bulged or leaking
capacitors, or any other sign of damage or discoloration.

5.2 TROUBLESHOOTING GUIDE

Be sure that all primary power to the machine has
been externally disconnected. Open wall discon­nect switch or circuit breaker before attempting
inspection or work inside of the power source.

A. Unit Completely inoperative. Fan does not run.

1. Open line fuses -- check the line fuses for
continuity and replace if necessary. If the fuses
continue to open, the jumper links may not be in
proper position. See primary electrical connec­tions in section 2.3.

2. No power input -- check position of line discon­nect switch.

3. Improper jumper link placement on input termi­nal board. See primary electrical connections in
section 2.3.

3. Tig/Stick switch TSS in the TIG position without
a remote contactor control connected to the
remote torch receptacle RTR. Place TSS in the
STICK position or make remote torch connec­tion at RTR.

4. Defective TSS and/or wiring. Check continuity
and replace if necessary.

5. Defective SCR p/c board.

6. Defective Current Range Switch SW1 (located
on SCR p/c board). Check continuity of SW1
and ensure that all connections are secure and
correct. Replace SW1 if defective.

7. Defective current selector switch CSS and/or
wiring. Check continuity of CSS and ensure that
all connections are secure and correct. Replace
CSS if defective.

8. Defective Current Control Potentiometer R44
(located on SCR p/c board). To check continuity
of R44, put Panel-Remote switch (PRS) in RE­MOTE position. Disconnect TC-1 or FC-4 Re­mote control. Check resistance between termi­nals "X" and "W" of Remote Current Control
receptacle (RCC) by rotating Current Control
potentiometer (R44). Resistance should vary
between "0" and 13.3 K to 16.7 K ohms. If pot
checks good, replace SCR p/c board.

9. The 3-amp control fuse may be blown -- check
and/or replace.

C. Low or unstable open circuit voltage.

1. Current control pot set too low for welding appli­cation. Increase setting of CCP.

4. Defective ROS and/or wiring -- check continuity
of ROS and replace if necessary.

B. No welding output. Fan operative.

1. Improper jumper link placement on input termi­nal board -- See primary electrical connections in
section 2.3.

2. Power source magnetics overheating -- thermal
switch (TS) tripped due to restricted cooling air
flow, or overextended duty cycle. Allow unit to
cool down for at least 5 minutes with fan running
to let TS reset.

2. Defective SCR in main bridge. Check the resis­tance across the SCR on the Rx1 scale. If the
reading is high the SCR is working. If the
resistance is low or zero the SCR is defective.
To check the gate, connect the gate lead to the
anode of the SCR and read the forward resis­tance across the SCR anode to cathode. If the
internal voltage of the meter is high enough, the
meter should read a low resistance.

3. Defective diode in main bridge. Place the cur­rent selector switch between position so as to
provide an open circuit across the diodes. On
the Rx1 scale check the resistance in the forward
and reverse directions. A good diode will read

21

SECTION 5 TROUBLESHOOTING

high in the reverse direction and low in the
forward direction. Replace defective parts.

4. Defective CSS and/or wiring. See troubleshoot­ing 2-g.

5. Defective SCR p/c board.

D. Erratic output welding current.

1. Intermittent shunt connections. Check connec­tions to shunt.

2. Defective SCR and/or diode in main bridge. See
troubleshooting 3-b and 3-c.

3. Defective SCR p/c board. Replace SCR p/c
board.

4. Excessive high frequency. Check spark gaps
and adjust if necessary (see Maintenance Sec­tion). Check all connections and components in
high frequency bypass circuit and replace any
defective components.

2. Defective SCR p/c board. Replace if defective.

I. Absence of High Frequency while selector switch

(HFS) is in START mode only.

1. Open circuit voltage low -- check remote contactor
switch or Tig/Stick Mode Switch TSS.

2. CCP or remote current control not set high
enough.

3. SCR p/c board may be defective.

J. Insufficient or Absence of H.F.

1. High frequency switch in the OFF position. Check
HFS and place in START or CONTINUOUS
position.

2. Improper spark gap Clean and adjust spark
gaps, if necessary. See spark Gap servicing.

3. Defective wiring to High Frequency Intensity pot,
or pot itself may be defective.

E. Erratic output at welding currents above 200

amps (approx.).

Input voltage falling below 10% of rated voltage
while machine is under load. May have to
increase input power conductor size or decrease
length.

F. Low Welding output in High range.

Current Range Switch SW1 (located on SCR p/
c board) may not be closing when positioned in
HIGH range. Check continuity of SW1 on SCR
p/c board -- replace if defective.

G. Minimum welding output in both current ranges.

1. Check for defective Current Control Potentiom­eter R44 (located on SCR p/c board) using
procedure outlined in Step 2-h.

2. Faulty wiring to Panel/Remote switch, or switch
itself may be defective.

H. High weld output, current control does not vary

the output.

4. Defective HFS and/or wiring. Make continuity
check and replace if necessary.

5. Defective Logic p/c board.

K. No gas and/or water flow.

1. High Frequency Switch (HFS) in OFF (Stick)
position -- place in Start or Continuous Mode(s).
Make continuity check, if necessary, and replace
if defective.

2. GS and/or WS solenoid defective. Check 24
V ac across solenoid coil. If present, and sole­noid does not energize, replace it.

L. No remote contactor control.

TIG/STICK switch in the STICK position. Place
TSS switch in the TIG position.

1. Open shunt connection. Check connections on
shunt.

22

SECTION 5 TROUBLESHOOTING

♦

Figure 5-1. Heliarc 350 AC/DC Schematic Diagram - 208/230/460 V ac, 1 Phase, 60 Hz

♦Installed in units with Power Factor

Correction (PFC). Optional for units

without PFC.

23

SECTION 5 TROUBLESHOOTING

24

Figure 5-2. Heliarc 350 AC/DC Wiring Diagram - 208/230/460 V ac, 1 Phase, 60 Hz (Sheet 1 of 2)

SECTION 5 TROUBLESHOOTING

Correction (PFC). Optional for units

without PFC.

♦Installed in units with Power Factor

♦

Figure 5-2. Heliarc 350 AC/DC Wiring Diagram - 208/230/460 V ac, 1 Phase, 60 Hz (Sheet 2 of 2)

25

SECTION 5 TROUBLESHOOTING

SECTION 6

REPLACEMENT PARTS

6.1 GENERAL

Replacement Parts are illustrated on the following
figures. When ordering replacement parts, order by
part number and part name, as illustrated on the figure.
DO NOT ORDER BY PART NUMBER ALONE.

Always provide the series or serial number of the unit
on which the parts will be used. The serial number is
stamped on the unit nameplate.

6.2 ORDERING

To assure proper operation, it is recommended that
only genuine ESAB parts and products be used with
this equipment. The use of non-ESAB parts may void
your warranty.

Replacement parts may be ordered from your ESAB
distributor or from:

ESAB Welding & Cutting Products

Attn: Customer Service Dept.
PO Box 100545, Ebenezer Road
Florence, SC, 29501-0545

Be sure to indicate any special shipping instructions
when ordering replacement parts.

To order parts by phone, contact ESAB at 1-803-664­5540 or 4460. Orders may also be faxed to 1-800-634-

7548. Be sure to indicate any special shipping instruc­tions when ordering replacement parts.

Refer to the Communication Guide located on the last
page of this manual for a list of customer service phone
numbers.

26

SECTION 6

(F1) 5 AMP FUSE - 97W06
FUSEHOLDER - 182W15

(2) HANDLES - 30596

LOCATION FOR OPTIONAL ANALOG METER
MODULE - 680628 (See Fig. 6-5)

(HIGH-LOW CURRENT RANGE SW. Is Integral Part
of SCR CONTROL P.C. BOARD ASSY. - 674976*)

TOP COVER - 30589YL
WARNING DECAL - 2091514

REPLACEMENT PARTS

(PFP) KNOB - 950584
POSTFLOW CONTROL POT & HI FREQ CONTROL
SW. Are Integral Part of LOGIC P.C.
BOARD ASSY. - 675421

BALANCE CONTROL Includes:
(BP) BAL. POTENTIOMETER - 639541
KNOB - 950584
RESISTOR ASSY - 30157, Includes:
(R101) 221K, 1% - 17111422
(R102) 1 MEG, 1% - 17111510

(AFP) KNOB - 950584
ARC FORCE CONTROL POT & SOFT START SW.
Are Integral Part of SOFT START P.C.
BOARD ASSY. - 675492

(SW1) TIG-STICK SW. 950812

(SW2) PANEL-REMOTE CURRENT SW. - 950812

(CCP) CURRENT CONTROL POT. ASSY. - 31065*
(CCP) KNOB - 950584

LOCATION FOR OPTIONAL SLOPE/SPOTWELD
CONTROL MODULE - 680665 (See Fig. 6-6)

BLANK PLATE (680660) LOCATION FOR:
(OPTIONAL) LOW AMP KIT - 680631†; OR
(OPTIONAL) PANEL-MT'D. PULSE
CONTROL MODULE - 680693 (See Fig. 6-7)

WATER DRAIN & TORCH GAS POWER
OUTPUT BLOCK ASSY. - 30612

UPPER PANEL SILKSCREENED - 31063

PLUMBING/OUTPUT TERMINAL
SILKSCREEN PANEL - 30601GY
PLUMBING/OUTPUT TERMINAL
COVER (Not Shown) - 30593GY

WATER BULKHEAD ADAPTOR, L.H. "B"
FEMALE TO 1/4" NPT MALE - 58V75
3/16" HOSE NIPPLE, 1/4" NPT FEMALE - 950510

(FCT) H.F. FERRITE CORE TRANSF. - 30573

†LOW AMP KIT - P/N 680631; Includes: SILKSCREEN MTG. PLATE - 680932,
ON-OFF SW. ASSY. - 680934, SW. KNOB - 2062171, INDUCTOR ASSY, ­680953 (For Mtg. Location, See Left Side View).

(SG) SPARK GAP ASSY. - 680036
Includes:
P.C. BOARD ASSY. - 675425
(2) HEAT SINKS - 673579
(2) SPARK GAP POINTS - 673578
(1) CAPACITOR - 950256

(ROS) ON-OFF POWER SW. - 950945

(HFI) H.F. INTENSITY RHEOSTAT - 993439
KNOB - 950584

(CSS) CURRENT SELECT SW. - 680676
KNOB - 2062171
(C-10, -13) CAPACITOR - 950702

(J3) REMOTE CURRENT RECPT. - 98W10
(C-22, -23, -24) CAPACITOR - 674216

(J4) REMOTE CONTACTOR RECPT. - 84W31
(C-25, -26) CAPACITOR - 674216

(2) OUTPUT TERMINAL ASSYS. - 676740

(HFTR) H.F. TRANSFORMER - 950573

H.F. ENCLOSURE COVER (Not Shown) - 30592

Figure 6-1. Heliarc 350 AC/DC (Front View)

27

SECTION 6

(T4) 5 POS. TERM. STRIP - 950286

Reference: T5 Terminal STANDOFF

GAS BULKHEAD ADAPTOR, R.H. "B" FEMALE
TO 1/4" NPT MALE - 58V58
(GSV) GAS SOLENOID VALVE - 950249
3/16" HOSE NIPPLE, 1/4" NPT MALE - 950263
(R9) RESISTOR, 470 ohm, 2w - 17140147

WATER BULKHEAD ADAPTOR L.H. "B"
FEMALE TO 1/4" NPT MALE - 58V75
3/16" HOSE NIPPLE, 1/4" NPT FEMALE ­950510

MOUNTING LOCATION FOR, OPTIONAL
LOW AMP KIT (P/N 680631),
INDUCTOR ASSY. - 680953

MOUNTING LOCATION FOR POWER
FACTOR KIT CAPACITORS (Factory­installed in units with power factor correction)
P.F. KIT - P/N 680632, Includes:
(3) CAP., 60 µF, 440 VAC - 950519
(1) MOUNTING BRACKET - 678619

REPLACEMENT PARTS

Figure 6-2. Heliarc 350 AC/DC (Left Side View)

DUST COVER (Not Shown) - 680675

(F2) FUSE, 1/2 AMP - 996523
FUSE BLOCK - 96W10

(TSR) RELAY - 950760

(BR) BRIDGE ASSY. - 30584
(Also see Fig. 6-4)

(T2) 5 POS. TERM. STRIP - 950826
(R10) RESISTOR, 10K, 1/2w - 17125310
(D3) DIODE, 1N4007 - 950415

(R105) RES. 100 ohm, 50w - 17250110
(Bet. Work Term & Chassis Ground)

(R6) RESISTOR, 150 ohm, 50w - 17250115
(R7) RESISTOR, 10 ohm, 50w - 17250010

(FN1) FILTER NETWORK ASSY. - 674971

LEFT SIDE PANEL (Not Shown) - 30591YL

(R3, R104) RESISTOR, 8 ohm, 300w - 17300008
(2-ea.) CENTERING WASHERS - 91W19
(2-ea.) MICA WASHERS - 647182

(T1) 5 POS. TERM. STRIP - 950826

(R106) RESISTOR, 20 ohm, 300w - 17300020
(2) CENTERING WASHERS - 91W19
(2) MICA WASHERS - 647182

(C11) CAP, 10 µF, 370 v - 672772

(FN2) FILTER NETWORK - 680042
Includes:
(MOV) MET. OXIDE VARISTOR - 995104
(C1, C2) 0.01 µF, 125v - 950702
(C3) 1.0 µF, 600 v - 993716

Figure 6-3. Heliarc 350 AC/DC (Right Side View)

(MTR) MAIN TRANSF - 30577
(TSA, TSB) THERMAL SWS, 160 °C ­673374 (One inserted each winding)

115 VAC Duplex Outlet - 647298

15 AMP CIRCUIT BKR. - 950188

(FM) FAN MOTOR - 2062334

FAN BLADE - 672189
FAN SHROUD - 672330

(HRTR) REACTOR - 30581
(RTSA, RTSB) THERMAL SWS. 180 °C ­2062211 (One inserted in each coil).

SILKSCREEN REAR PANEL - 30599

INPUT TERMINAL BOARD
ASSY. - 680047

GROUND TERM. LUG - 647361

RIGHT SIDE PANEL (Not Shown) ­30590YL
RIGHT SIDE T.B. COVER (Not
Shown) - 30429YL

28

SECTION 6

REPLACEMENT PARTS

Figure 6-4. Bridge Assembly (P/N 30584)

Figure 6-5. Analog Meter Module (P/N 680628)

Figure 6-6. Slope/Spotweld Control Module

(P/N 680665)

29

SECTION 6

REPLACEMENT PARTS

Figure 6-7. Panel Pulse Control Assembly

(P/N 680693)

30

SECTION 6

REPLACEMENT PARTS

31

Notes

COMMUNICATIONS GUIDE

A. CUSTOMER SERVICE QUESTIONS: Telephone: [phone] / FAX: [phone]

Order Entry Product Availability Pricing Order Changes Hours: 8:30 AM to 5:00 PM EST

B. ENGINEERING SERVICE: Telephone: [phone] or -5550 / FAX: [phone]

Welding Equipment Troubleshooting Warranty Returns Hours: 7:30 AM to 5:00 PM EST

C. TECHNICAL SERVICE: Telephone: [phone] / FAX: [phone]

Part Numbers Technical Applications Hours: 7:30 AM to 5:00 PM EST
Performance Features Technical Specifications

D. LITERATURE REQUESTS: Telephone: [phone] / FAX: [phone]

E. WELDING EQUIPMENT REPAIRS: Telephone: [phone] / FAX: [phone]

Repair Estimates Repair Status Hours: 7:30 AM to 3:30 PM EST

F. WELDING EQUIPMENT TRAINING: Telephone: [phone] / FAX: [phone]

Training School Information and Registrations Hours: 7:30 AM to 4:00 PM EST

G. WELDING PROCESS ASSISTANCE: Telephone: [phone] / FAX: [phone]

H. TECHNICAL ASST. CONSUMABLES: Telephone: [phone]

IF YOU DO NOT KNOW WHOM TO CALL

Telephone: [phone] and [phone]

Hours: 7:30 AM to 5:00 PM EST

Hours: 7:30 AM to 4:00 PM EST

Hours: 7:30 AM to 4:00 PM EST

Hours: 7:30 AM to 5:00 PM EST

F-14-447-A 4/95 1.5M Printed in U.S.A.

ESAB Welding & Cutting Products

PO Box 100545 Florence SC 29501-0545