Middleby PS520 Operation Manual

MiddlebyMiddleby

Middleby

MiddlebyMiddleby
MarshallMarshall

Marshall

MarshallMarshall

A MIDDLEBY COMPANY

owner's
operating

& installation

manual

PS520-Series Gas Ovens: English

November 12, 2008

®

PS520-Series

Model

PS520G

OVENS

PS520 (Single)

PS520 (Double)

©2006 Middleby Marshall Inc.

PS520 (Triple)

Part No. 59223 Rev. B

Price $30.00

P: 11/08

NOTICE:
This Owner's Operating and Installation Manual should be given to the user. The operator of the oven should

be familiar with the functions and operation of the oven.
This manual must be kept in a prominent, easily reachable location near the oven.
Ovens are shipped from the factory configured for use with natural gas. If permitted by local, national and

international codes, at the time of installation the oven may be converted to propane gas operation. This
conversion requires the use of at Gas Conversion Kit that is supplied with the oven. For CE-approved ovens,
the conversion is described in the Installation section of this Manual. For domestic and standard export ovens,
instructions are included in the Gas Conversion Kit.

It is suggested to obtain a service contract with a Middleby Marshall Authorized Service Agent.

WARNING

POST, IN A PROMINENT LOCATION, THE EMERGENCY TELEPHONE NUMBER OF YOUR LOCAL

GAS SUPPLIER AND INSTRUCTIONS TO BE FOLLOWED IN THE EVENT YOU SMELL GAS.

Instructions to be followed in the event the user smells gas shall be obtained by consulting the local gas

supplier. If the smell of gas is detected, immediately call the emergency phone number of your local Gas

Company. They will have personnel and provisions available to correct the problem.

WARNING

FOR YOUR SAFETY, DO NOT STORE OR USE
GASOLINE OR OTHER FLAMMABLE VAPORS AND
LIQUIDS IN THE VICINITY OF THIS OR ANY OTHER

APPLIANCE.

WARNING

Improper installation, adjustment, alteration, service, or
maintenance can cause property damage, injury, or
death. Read the installation, operation, and maintenance
instructions thoroughly before installing or servicing this
equipment.

NOTICE

The warranty is
demonstrated under the supervision of a factory-authorized installer.

Contact your authorized Service Agency to perform maintenance and

repairs. A Service Agency Directory is supplied with your oven.

Using any parts other than genuine Middleby Marshall factory-manufactured
parts relieves the manufacturer of all warranty and liability.

Middleby Marshall (Manufacturer) reserves the right to

NOT VALID

unless the oven is installed, started, and

NOTICE

NOTICE

NOTICE

change specifications at any time.

KEEP THIS MANUAL IN A VISIBLE LOCATION NEAR THE OVEN

FOR FUTURE REFERENCE.

ii

Model No.
Modéle No.

Serial No.
Serié No.

Installation Date
Date d'installation

MIDDLEBY MARSHALL

NO QUIBBLE LIMITED WARRANTY

(U.S.A. ONLY)

MIDDLEBY MARSHALL, HEREINAFTER REFERRED TO AS
“THE SELLER”, WARRANTS EQUIPMENT MANUFACTURED
BY IT TO BE FREE FROM DEFECTS IN MATERIAL AND
WORKMANSHIP FOR WHICH IT IS RESPONSIBLE. THE
SELLER’S OBLIGATION UNDER THIS WARRANTY SHALL
BE LIMITED TO REPLACING OR REPAIRING, AT SELLER’S
OPTION, WITHOUT CHARGE, ANY PART FOUND TO BE
DEFECTIVE AND ANY LABOR AND MATERIAL EXPENSE
INCURRED BY SELLER IN REPAIRING OR REPLACING
SUCH PART. SUCH WARRANTY SHALL BE LIMITED TO
THE ORIGINAL PURCHASER ONLY AND SHALL BE EFFEC­TIVE FOR A PERIOD OF ONE YEAR FROM DATE OF ORIGI­NAL INSTALLATION, OR 18 MONTHS FROM DATE OF PUR­CHASE, WHICHEVER IS EARLIER, PROVIDED THAT TERMS
OF PAYMENT HAVE BEEN FULLY MET.

This warranty is valid only if the equipment is installed, started,
and demonstrated under the supervision of a factory-autho­rized installer.

Normal maintenance functions, including lubrication, clean­ing, or customer abuse, are not covered by this

warranty

Seller shall be responsible only for repairs or replacements
of defective parts performed by Seller’s authorized service
personnel. Authorized service agencies are located in prin­cipal cities throughout the contiguous United States, Alaska,
and Hawaii. This warranty is valid in the 50 United States
and is void elsewhere unless the product is purchased
through Middleby International with warranty included.

.

The foregoing warranty is exclusive and in lieu of all other
warranties, expressed or implied. There are no implied
warranties of merchantability or of fitness for a particu­lar purpose.

The foregoing shall be Seller’s sole and exclusive obligation
and Buyer’s sole and exclusive remedy for any action, in­cluding breach of contract or negligence. In no event shall
Seller be liable for a sum in excess of the purchase price of
the item. Seller shall not be liable for any prospective or lost
profits of Buyer.

This warranty is effective on Middleby Marshall equip­ment sold on, or after, February 15, 1995.

no quibble

MIDDLEBY MARSHALL INC.

OVEN LIMITED WARRANTY

(Non U.S.A.)

The Seller warrants equipment manufactured by it to be free from
defects in material and workmanship for which it is responsible. The
Seller’s obligation under this warranty shall be limited to replacing or
repairing, at Seller’s option, without charge, F.O.B. Seller’s factory,
any part found to be defective and any labor and material expense
incurred by Seller in repairing or replacing such part. Such warranty
is limited to a period of one year from date of original installation or
15 months from date of shipment from Seller’s factory, whichever is
earlier, provided that terms of payment have been fully met. All labor
shall be performed during regular working hours. Overtime premium
will be charged to the Buyer.

This warranty is not valid unless equipment is installed, started,
and demonstrated under the supervision of a factory-autho­rized installer.

Normal maintenance functions, including lubrication, adjustment of
airflow, thermostats, door mechanisms, microswitches, burners
and pilot burners, and replacement of light bulbs, fuses and indicat­ing lights, are not covered by warranty.

Any repairs or replacements of defective parts shall be performed by
Seller’s authorized service personnel. Seller shall not be respon­sible for any costs incurred if the work is performed by other than
Seller’s authorized service personnel.

When returning any part under warranty, the part must be intact and
complete, without evidence of misuse or abuse, freight prepaid.

Seller shall not be liable for consequential damages of any kind
which occur during the course of installation of equipment, or which
result from the use or misuse by Buyer, its employees or others of
the equipment supplied hereunder, and Buyer’s sole and exclusive
remedy against Seller for any breach of the foregoing warranty or
otherwise shall be for the repair or replacement of the equipment or
parts thereof affected by such breach.

The foregoing warranty shall be valid and binding upon Seller if and
only if Buyer loads, operates and maintains the equipment supplied
hereunder in accordance with the instruction manual provided to
Buyer. Seller does not guarantee the process of manufacture by
Buyer or the quality of product to be produced by the equipment
supplied hereunder and Seller shall not be liable for any prospective
or lost profits of Buyer.

THE FOREGOING WARRANTY IS EXCLUSIVE AND IN LIEU OF
ALL OTHER EXPRESS AND IMPLIED WARRANTIES WHATSO­EVER. SPECIFICALLY THERE ARE NO IMPLIED WARRANTIES
OF MERCHANTABILITY OR OF FITNESS FOR A PARTICULAR
PURPOSE.

The foregoing shall be Seller’s sole and exclusive obligation and
Buyer’s sole and exclusive remedy for any action, whether in breach
of contract or negligence. In no event shall seller be liable for a sum
in excess of the purchase price of the item.

© 2003 - Middleby Marshall, A Middleby Company.
The Middleby Marshall logo is a registered trademark of Middleby Marshall, A Middleby Company.

Middleby Marshall Inc. • 1400 Toastmaster Drive • Elgin, Illinois 60120-9272 U.S.A. • [phone] • FAX: [phone]

iii

TABLE OF CONTENTS

Page

SECTION 1

I. MODEL IDENTIFICATION .............................................. 1

SERIES PS520 GAS SPECIFICATIONS ............................ 2

II. COMPONENT FUNCTION ............................................. 4

A. Conveyor Motor and Conveyor Belt ........................ 4

B. Blower Fan ................................................................. 4

C. Gas Burner ................................................................ 4

D. Cooling Fan ................................................................ 4

E. Air Fingers and Blank Plates - See Figure 1-9 ........ 4

SECTION 2

I. UNLOADING ................................................................... 8

PARTS LIST FOR SERIES PS520 GAS OVEN

INSTALLATION KIT .................................................... 8

UTILITY ROUGH-IN DIMENSIONS AND POSITIONING

FOR PS520-SERIES OVENS .................................... 13

CIRCUIT BREAKER ..................................................... 13

ELECTRICAL SPECIFICATIONS ................................. 13

ELECTRICAL RATING ................................................. 13

SUPPLY WIRE .............................................................. 13

SUGGESTED ................................................................ 13

II. VENTILATION GUIDELINES ........................................ 13

III. ELECTRICAL CONNECTION INFORMATION FOR

PS520-SERIES OVENS. ........................................... 14

IV. ELECTRIC SUPPLY FOR GAS HEATED OVENS ..... 14

V. GAS SUPPLY .............................................................. 15

SECTION 3 INSTALLATION

I. CONTROL FUNCTIONS ................................................ 19

II. COMPONENT INFORMATION AND LOCATION ......... 20

A. Door Safety Switch .................................................. 20

B. Blower Switch .......................................................... 20

C. Heat Switch .............................................................. 20

D. Temperature Controller .......................................... 20

E. Conveyor ................................................................. 21

MEASURING CONVEYOR SPEED. ............................. 21

TABLE OF CONTENTS

(Continued)

Page

III. STEP-BY-STEP OPERATION ....................................... 22

A. Startup Procedures ................................................. 22

Daily Startup ................................................................. 22

Power Failure ............................................................... 22

B. Shutdown Procedure ............................................... 22

IV. NORMAL OPERATION - STEP-BY-STEP ................... 24

A.Daily Startup Procedure ........................................... 24

B. Daily Shutdown Procedure ...................................... 24

V. QUICK REFERENCE: TROUBLESHOOTING ............ 26

SECTION 4 MAINTENANCE

I. MAINTENANCE - DAILY ............................................ 28

A. Exterior ..................................................................... 28

B. Cooling Fan ............................................................... 2 8

C. Conveyor Belt .......................................................... 2 8

D. Crumb Pans ............................................................. 28

II. MAINTENANCE - MONTHLY ....................................... 29

A. Removing Conveyor From Oven For Cleaning ..... 29

B. Air Fingers Disassembly For Cleaning .................. 31

C. Reassembly of Air Fingers ..................................... 32

D. Reinstall End Plugs ................................................. 35

E. Conveyor Reassembly Into Oven .......................... 36

F. Checking Conveyor Belt Tension ........................... 36

G. Conveyor Belt Link Removal ................................. 37

H. Attaching Drive Chain ............................................. 3 8

III. MAINTENANCE - EVERY 3 MONTHS ......................... 39

A. Electrical Terminals ................................................ 39

B. Ventilation ................................................................ 39

IV. MAINTENANCE - EVERY 6 MONTHS ........................ 39

PS520-SERIES GAS OVEN KEY SPARE

PARTS ....................................................................... 40

KEY SPARE PARTS KIT ............................................... 40

SECTION 5 TROUBLESHOOTING

Troubleshooting Charts ...................................................... 4 1

SECTION 6 ELECTRICAL SCHEMATICS

Wiring Diagram, G208-240V 50/60 GO, PS520 ............... 4 3

iv

NOTE

Wiring Diagrams are in Section 6 of this Manual.

The diagram for each oven is also on the lower

inner surface of its Control Console.

SECTION 1

DESCRIPTION

I. MODEL IDENTIFICATION

The Middleby Marshall PS520-Series may be used either
as a single oven or stacked for use as double or triple
ovens.

A single PS520-Series Oven (Figure 1-1) is mounted on a
base pad with legs. A double oven (Figure 1-2) consists of
two,

stacked,

consists of three stacked single ovens. The lower oven is
mounted on a base pad with stacking pins.

On a double or triple oven, the ovens operate indepen­dently. All ovens use identical controls and components.
One oven can be cleaned or serviced, while the others are
operating.

single ovens. A triple oven (Figure 1-3)

SECTION 1

DESCRIPTION

Figure 1-1. Single PS520 Oven

Figure 1-2. Double PS520 Oven

Figure 1-3. Triple PS520 Oven

1

SECTION 1
DESCRIPTION

PS520 SERIES OVEN SPECIFICATIONS

Conveyor Belt Width 18.00″ (457mm)
Heating Zone Length 20.00″ (5098mm)
Baking Area Square Feet 2.5 sq. ft. (0.23 sq. m.)
Overall Dimension – Standard Single Oven w/Legs 42.00″ (1067mm) L ×

Overall Dimension – Double Oven 42.00″ (1067mm) L ×

Overall Dimension – Triple Oven 42.00″ (1067mm) L x

Weight of Single Oven 250 lb (93.3kg)
Shipping Weight 325 lb (121.3kg)
Shipping Cube 22.1 ft3 (0.62 m3)
Operating Range 8.3 kW/hr
BTU's – Natural or Propane Gas 40,000 BTU/HR
Gas Input – Natural or Propane Gas 1/2″ NPT
Maximum Operating Temperature 600°F (316°C)
Warm-up Time 20 min.
Belt Speed Limits 1-10 minutes

35.21″ (894mm) W ×

21.10″ (536mm) H ×

35.21″ (894mm) W ×

36.64″ (931mm) H x

35.21″ (894mm) W ×

48.19″ (1224mm) H ×

SERIES PS520 ELECTRICAL SPECIFICATIONS

Main Blower & Control Circuit Phase Frequency Amperage Poles Wires

Elements Voltage Voltage Draw

208-240V 208-240V 1 Ph 50/60 Hz 1.5 Amp 2 Pole 3 Wire

GAS ORIFICE AND PRESSURE SPECIFICATIONS (PER OVEN CAVITY) - DOMESTIC AND STANDARD EXPORT OVENS

Gas Type Main Orifice I.D. Supply (Inlet) Pressure Pressure

Natural 0.082” (2.08mm, #45 drill) 6-12” W.C. (14.9-29.9mbar) * 3.5” W.C. (8.72mbar)
Propane 0.057” (1.45mm, #46 drill) 11-14” W.C. (27.4-34.9mbar) * 7” W.C. (17.44mbar)

* The gas supply pressures and orifice sizes shown are for ovens installed in North America. The required gas supply pressures and orifice

sizes of ovens installed in other locations are dependent on the local gas type and on all applicable local codes.

Orifice (Manifold)

GAS ORIFICE AND PRESSURE SPECIFICATIONS (PER OVEN CAVITY) - CE OVENS

Supply (Inlet) Pressure

Gas Orifice DK,FI DE BE,FR FI,DE,NL ES,UK (Manifold) Heat

Main UK,CH,IT,AT, SE,CH,AT,DK, BE,IE,IT,PT, Orifice Rated

Type dia.

G20 2.3749 20 20 20 -- -- 11.21 22.36

mm mbar mbar mbar mbar kW-hr.

G25 2.3749 -- -- -- -- - - 16.19 22.36

mm mbar kW-hr.

G30 1.3970 -- -- -- 29 or 50 28-30, 37 26.2 22.59

mm mbar or 50 mbar mbar kW-hr.

IT,PT,ES,SE,

I

2H

I

2E

I

2E+

I

3B/P

I

3+

Pressure Input

(2 hot, 1 grd)

NOTE

Wiring Diagrams are contained in Section 6 of this Manual

and are also located inside the oven at the

bottom of the Control Panel.

Additional electrical information is provided on the oven's serial plate.

This Manual Must Be Kept For Future Reference.

2

II. COMPONENT FUNCTION (Figure 1-4)

SECTION 1

DESCRIPTION

Figure 1-4. PS520-Series Oven Components Locations

3

SECTION 1
DESCRIPTION

II. COMPONENT FUNCTION

A. Conveyor Motor and Conveyor Belt

The conveyor belt is driven by a variable-speed electric
motor (Figure 1-5) operating through a gear reducer. The
motor speed is controlled by a digital control. The stain­less-steel wire belt can travel in either direction at variable
rates ranging from 3 minutes to 30 minutes; this is the time
that a product can take to pass through the oven.

B. Blower Fan

The blower fans are located at the rear of the oven. These
blowers force heated air through the air fingers. The
BLOWER switch must be set to “ON” or “I” for oven
warmup and baking.

C. Gas Burner

The gas burner is located inside the rear panel and is
controlled by the temperature controller.

D. Cooling Fan — See Figure 1-5 and Figure 1-6

The cooling fan is located in the back of the oven. The
cooling fan draws air through its grille, blowing it through
the blower motor compartment and the control compart­ments into the oven top and exhausted out the front
louvers.

E. Air Fingers and Blank Plates - See Figure 1-7

E1. Air Fingers

An Air Finger Assembly is made up of three parts:

1. Outer Plate - The Outer Plate is the removable covering
with tapered holes, which direct the air stream onto the
product being baked.

2. Inner Plate -The perforated Inner Plate is vital in forming
the unique air jets. It must be assembled into the manifold
with its holes aligned with the holes of the outer plate.

3. Manifold - The Manifold is the assembly which slides
on tracks into the oven plenum.

Blower Assembly

Right Control Box

Figure 1-5. Machinery Compartment

Components

4

SECTION 1

DESCRIPTION

Figure 1-6. Cooling Fan

5

SECTION 1
DESCRIPTION

Half Blank Plate

F2. Blank Plates

1. Blank Plates- The Blank Plates are available to install
on the plenum where an air finger is not required.

Outer Plate

Blank Plate

Inner Plate

Finger
Manifold
Assembly

Baffle

Figure 1-7. Blank Plates (two sizes) and an Air Finger.

6

SECTION 2

SECTION 2

INSTALLATION

INSTALLATION

WARNING - For gas ovens, after any conversions, readjustments, or service work on the oven:

• Perform a gas leak test.

• Test for correct air supply.

• Test for proper combustion and gas supply.

• Check that the ventilation system is in operation.

WARNING

Keep the appliance area free and clear of combustibles.

WARNING
The oven must be installed on an even (level) non-flammable flooring and any adjacent walls must
be non-flammable. Recommended minimum clearances are specified in the Description section of

this Manual.

WARNING

Do not obstruct the flow of combustion and ventilation air to and from your oven. There must be no

obstructions around or underneath the oven. Constructional changes to the area where the oven is

installed shall not affect the air supply to the oven.

CAUTION

For additional installation information, contact your local Authorized Service Agent.

NOTE

There must be adequate clearance between the oven and combustible construction. Clearance

must also be provided for servicing and for proper operation.

NOTE

An electrical wiring diagram for the oven is located inside the machinery compartment.

NOTE

All aspects of the oven installation, including placement, utility connections, and ventilation requirements,

must conform with any applicable local, national, or international codes. These codes supersede the

requirements and guidelines provided in this manual.

NOTE

In the USA, the oven installation must conform with local codes. In the absence of local codes, gas oven

installations must conform with the National Fuel Gas Code, ANSI Z223.1. Installed ovens must be

electrically grounded in accordance with local codes, or in the absence of local codes, with the National

Electrical Code (NEC), or ANSI/NFPA70.

NOTE

In Canada, the oven installation must conform with local codes. In the absence of local codes, gas oven

installations must conform with the Natural Gas Installation Code, CAN/CGA-B149.1, or the Propane Gas

Installation Code, CAN/CGA-B149.2, as applicable. Installed ovens must be electrically grounded in

accordance with local codes, or in the absence of local codes, with the Canadian Electrical Code CSA C22.2.

NOTE

In Australia, the oven installation must conform with any requirements of the appropriate statutory authority.

Gas oven installtions must conform with AGA Codes AG311 and AG601.

NOTE

In CE countries, all aspects of the gas supply connection must comply with current IEC/CEE requirements and

with all applicable local, national, and international codes. In addition, four casters are provided to allow the oven

to be more easily moved to the installation location. These casters are intended to simplify pre-installation

movement only, and are NOT suitable for use as part of a CE oven installation. During the installation procedure,

the casters MUST be removed, so that the oven can be supported by the supplied 152mm adjustable legs.

7

SECTION 2
INSTALLATION

NOTE: The oven, when installed, must be electrically
grounded in accordance with local codes, or in the ab­sence of local codes, with the National Electrical Code
(NEC), or ANSI/NFPA70.

NOTE

There must be adequate clearance between
the oven and any adjacent combustible con­struction. Clearance must also be provided
for servicing and for operation.

CAUTION

It is recommended that the oven be placed under
a ventilation hood for adequate air supply and
ventilation.

CAUTION

Do not obstruct the flow of ventilation air to and
from your oven. Do not obstruct the fan holes in
the rear of the unit.

I. UNLOADING

Your Middleby Marshall PS520-Series Oven is shipped
partially assembled. It will arrive in a carton on a crate.

Carton size for a PS520-Series Oven is:

44-1/4″ (1124mm) Long ×

37-1/2″ (953mm) Wide ×

23″ (584mm) High ×

The crate and carton must be examined before signing the
Bill of Lading. Report any visible damage to the transport
company, and check for the proper number of crates. If
apparent damage is found, make arrangements to file a
claim against the carrier. Surface Interstate Commerce
Regulations (U.S.A.) require that the claim must be
initiated by the consignee within 10 days from the date that
the shipment is received.

PARTS LIST FOR SERIES PS520 GAS OVEN

INSTALLATION KIT

Single Stack Oven

ITEM

NO. QTY PART NO. DESCRIPTION

1 4 3101908 LEG 4″ AD FT
2 2 48392 INSULATION BOTTOM TRAY
3 1 48394 BOTTOM TRAY WELDMENT
4 1 48396 TOP COVER
5 4 51387 SCREW MSSLT THREAD 8-32 × 1/2, 18-8
6 1 59223 OWNER'S OPERATING & INSTALLATION MANUAL
7 1 22450-0228 GAS HOSE RESTRAINT CABLE
8 1 22361-0001 GAS HOSE

P/N 59182

7

8

Figure 2-1. PS520-Series Gas Oven Installation Parts

8

INSTALLATION

PARTS LIST FOR SERIES PS520 Gas OVEN

INSTALLATION KIT

Double Stack Oven

ITEM

NO. QTY PART NO. DESCRIPTION

1 2 48392 INSULATION BOTTOM TRAY
2 1 48394 BOTTOM TRAY WELDMENT
3 1 48396 TOP COVER
4 4 51387 SCREW MSSLT THREAD 8-32 × 1/2, 18-8
5 4 3101908 LEG 4″ AD FT
6 1 59223 OWNER'S OPERATING & INSTALLATION MANUAL
7 1 22450-0228 GAS HOSE RESTRAINT CABLE
8 2 22361-0001 GAS HOSE

P/N 59183

SECTION 2

7

8

PARTS LIST FOR SERIES PS520 Gas OVEN

INSTALLATION KIT

Triple Stack Oven

ITEM

NO. QTY PART NO. DESCRIPTION

1 2 48392 INSULATION BOTTOM TRAY
2 1 48394 BOTTOM TRAY WELDMENT
3 1 48396 TOP COVER
4 4 51387 SCREW MSSLT THREAD 8-32 × 1/2, 18-8
5 4 M3828 PIN, ALIGNMENT
6 1 59223 OWNER'S OPERATING & INSTALLATION MANUAL
7 1 22450-0228 GAS HOSE RESTRAINT CABLE
8 3 22361-0001 GAS HOSE

P/N 59184

7

8

Figure 2-1 (continued). PS520-Series Gas Oven Installation Parts

9

SECTION 2
INSTALLATION

1

Figure 2-5. MODEL PS520 SINGLE OVEN DIMENSIONS

4.00

101.6mm

The Opening Height is Adjustable from 2-1/4 inch minimum

1

to 3-3/4 inch maximum in 1/2 inch increments.

10

SECTION 2

INSTALLATION

Figure 2-6. MODEL PS520 DOUBLE OVEN DIMENSIONS

1

4.00

101.6mm

The Opening Height is Adjustable from 2-1/4 inch minimum

1

to 3-3/4 inch maximum in 1/2 inch increments.

2

P/N 59927 is shown in its correct installed position.

11

SECTION 2
INSTALLATION

Figure 2-7. MODEL 520 TRIPLE OVEN DIMENSIONS

1

The Opening Height is Adjustable from 2-1/4 inch minimum

1

to 3-3/4 inch maximum in 1/2 inch increments.

2

P/N 59927 is shown in its correct installed position.

12

UTILITY ROUGH-IN DIMENSIONS AND POSITIONING

FOR PS520-SERIES OVENS

WARNING

DO NOT USE CONDUIT OR GAS LINE
FOR GROUND CONNECTION.

CAUTION

IT IS RECOMMENDED THAT THE OVEN
BE PLACED UNDER A VENTILATION
HOOD FOR ADEQUATE AIR SUPPLY
AND VENTILATION.

ELECTRIC SUPPLY TO BE

PROVIDED BY CUSTOMER

SECTION 2

INSTALLATION

CIRCUIT BREAKER

Separate circuit breaker with lockout/tagout electrical
shutoff for each oven. Wire each oven separately.

15A Amp circuit breaker for 208-240V.

ELECTRICAL SPECIFICATIONS

DOMESTIC: 208V main blower motors, 1 Ph, 1.5 Amp

draw, 50/60 Hz, 208-240V control circuit, 2 pole, 3 wire
system per oven (2 hot, 1 grd).

Do

NOT

use conduit for ground.

or

DOMESTIC or EXPORT: 240V main blower motors, 1 Ph,

1.5 Amp draw, 50/60 Hz, 208-240V control circuit, 2 pole,
3 wire system per oven (2 hot, 1 grd).

230V main blower motors, 1 Ph, 1.5 Amp draw, 50/60 Hz,
208-240V control circuit, 2 pole, 3 wire system per oven
(2 hot, 1 grd).

Do

NOT

use conduit for ground.

Figure 2-9. Typical PS520-Series Oven(s)

Installation

POWER RATING

40,000 BTU/hr (11.7 kW/hr.

SUPPLY WIRE

Supply wire size must be in accordance with the National
Electrical Code (current edition) and must be in compli­ance with local codes.

SUGGESTED

If space permits, service should be located near the
control console end of the oven(s) to allow convenient
access to safety switches.

CAUTION

UNIT MUST HAVE AIR VENT PLATES IN­STALLED OR WARRANTY WILL BE VOID.

II. VENTILATION GUIDELINES

A mechanically driven ventilation system is required for the
PS520 Series Middleby Marshall conveyorized gas ovens.

Local codes and conditions vary greatly from one area to
another and must be complied with. Following are the
suggested requirements for good ventilation. Please re­member these are recommendations or guidelines, you
may have a special condition or problem that will require
the services of a ventilation engineer or specialist. Proper
ventilation is the oven owner’s responsibility. Improper
ventilation can inhibit oven performance.

Please Note: There are now two “stand off”
‘C’ Channels and the “plate” for “Double
and Triple Ovens” that must be installed in
the field.

13

SECTION 2
INSTALLATION

These ‘C’ Channel brackets are installed in the vertical
plane using existing screws (Item 6) to support these ‘C’
Channels using the upper and lower Key Hole openings in
the ‘C’ Channels. The ‘C’ Channels are identical and once
installed will allow ample amounts of air through the cooling
fan mounted on the rear side of the oven by keeping the
oven away from the rear wall.

III. ELECTRICAL CONNECTION INFORMATION

FOR PS520-SERIES OVENS.

WARNING

Authorized supplier personnel normally ac­complish the connections for the ventilation
system, electric and gas supplies, as ar­ranged by the customer. Following these
connections, the factory-authorized installer
can perform the initial startup of the oven.

Check the oven data plate (Figure 2-10) before making any
electric supply connections. Electric supply connections
must agree with data on the oven data plate.

electrical code requirements. Copper is the recommended
material for the electrical supply conductors.

IV. ELECTRIC SUPPLY FOR GAS

HEATED OVENS

Power requirements for gas heated ovens are 208 ­240VAC, 1-phase, 3-wire (2 ‘hot’, 1 ground). Electrical
connection is made through a cord and plug. Using flexible
cable(s) for the electrical power supply conductors re­quires a 2″ (51mm) strain-relief fitting (not furnished) to
enable safe access to the terminal block from which oven
power is distributed.

The supply conductors must be of the size and
material (copper) recommended to provide the cur­rent required; (refer to the data plate for the ampere
specifications). The electric current rating for each
conductor supplying a PS520-Series Oven is 1.5A.

NOTE: The electric supply installation must satisfy the
requirements of the appropriate statutory authority, such
as the National Electrical Code (NEC), ANSI/NFPA70,
(U.S.A.); the Canadian Electrical Code, CSA C22.2; the
Australian Code AG601; or other applicable regulations.

A fused disconnect switch or a main circuit breaker
(customer furnished) MUST be installed in the electric
supply line for each oven; it is recommended that this
switch/ circuit breaker have lockout/tagout capability. The
electric supply connection must meet all national and local

ELECTRICAL

INLET

GAS INLET

Figure 2-11. Junction Connection Box

Figure 2-10. Typical Electric Oven Data Plate

14

SECTION 2

INSTALLATION

V. GAS SUPPLY

CAUTION

DURING PRESSURE TESTING NOTE THE FOLLOWING:

1. The oven and its individual shutoff valve must be discon­nected from the gas supply piping system during any
pressure testing of that system at test pressure in excess
of 1/2 psi (3.45 kPa).

2. The oven must be isolated from the gas supply piping
system by closing its individual manual shutoff valve
during any pressure testing of the gas supply piping
system at test pressure equal to or less than 1/2 psi (3.45
kPa).

3. If incoming pressure is over 14" W.C. (35mbar), a
separate regulator MUST be installed in the line BEFORE
the individual shutoff valve for the oven.

WARNING: To prevent damage to the control valve regu­lator during initial turn- on of gas, it is
open the manual shutoff valve very slowly.

After the initial gas turn-on, the manual shutoff valve must
remain open except during pressure testing as outlined
in the above steps or when necessary during service
maintenance.

A . Gas Utility Rough-In Recommendations

The following gas system specifications are STRONGLY
RECOMMENDED. Deviating from these recommendations
may affect the baking performance of the oven.

Gas Meter - 650 cfh (307

l/min) meter

Gas Line

• DEDICATED LINE from the gas meter to the oven

• 2" (50.8mm) pipe for natural gas

• 1-1/2" (38.1mm) pipe for propane

• Maximum length: 200' (61m). Each 90° elbow equals 7'
(2.13m) of pipe.

B . Gas Conversion

Where permitted by local and national codes, it is possible to
convert ovens from natural to propane gas, or from propane to
natural gas. Use the appropriate Middleby Gas Conversion Kit
for the specific oven model.

very important to

2. Connect a suitable pressure gauge to pipe line or to
outlet pressure tap of gas control concerned, to measure
burner pressure (measuring point must be as near to
burner as possible).

3. Make sure that the appliance is in operation and the
Moduplus® coil is energized with maximum current.

4. If maximum rate pressure needs adjustment, use an 8 mm
wrench to turn adjustment screw for maximum pressure
setting (clockwise to increase or counter-clockwise to de­crease pressure), until the desired maximum outlet pres­sure is obtained.

5. Disconnect electrical connection of the Moduplus

®

.

6. Check minimum pressure setting and readjust if neces­sary. (See Adjusting Minimum Pressure Setting for proper
adjusting procedure.)

7. Reconnect pressure feedback connection (if appcable).

8. If minimum and maximum pressures are set, wire the
Moduplus

®

in circuit.

9. Close pressure tap screw.

E. Adjusting the Minimum Pressure Setting

1. Disconnect pressure feedback connection (if appcable).

2. Connect a suitable pressure gauge to pipe line or to outlet
pressure tap of gas control concerned, to measure burner
pressure (measuring point must be as near to burner as
possible).

3. Disconnect electrical connection of the Moduplus

®

.

4. Energize operator, set control in operation and wait until an
outlet pressure is recorded on pressure gauge.

5. If minimum rate pressure needs adjustment, use an 8 mm
wrench to turn adjustment screw for minimum pressure
setting (clockwise to increase or counter-clockwise to
decrease pressure), until the desired minimum outlet
pressure is obtained.

6. Check if main burner lights easily and reliable at minimum
pressure.

7. Reconnect pressure feedback connection (if appcable).

8. Close pressure tap screw.

Figure 2-15 - Flexible Gas Hose Installation

CAUTION: The terms of the oven’s warranty require all start-

ups, conversions and service work to be per­formed by a Middleby Authorized Service Agent.

C . PS520 Propane Conversion

Two items have to be changed, to change the oven to LP:

1. Replace main orifices.

2. Adjust main gas regulator per instructions below.
Disconnect the manifold union closest to the main burner, and

remove the manifold assembly (four screws). Slide out the
manifold assembly (leaving the ignition and sense wires con­nected). Replace the main orifices.

Replace the main orifices on the manifold assemblies with the LP
units, and replace the manifold assembly. Reconnect the union.

D. Adjusting the Maximum Pressure Setting

1. Disconnect pressure feedback connection (if appcable).

1/2" gas line

tee with

pressure tap

15

1/2" gas

pipe nipple

Quick-

disconnect

device

3/4"-1/2"
gas pipe

reducer

3/4" gas

pipe nipple

90°

Elbow

Flexible

Gas Hose

To Gas

Supply

Pipe

Full-Flow

Gas

Shutoff

Valve

Individual gas

connection for

each oven

cavity

SECTION 2

y

INSTALLATION

Figure 2-16. Gas Burner Assembly

Gas Burner

Manifold Pressure Tap

Figure 2-17. Burner Assembly

Gas

Valve

Main•

Pressure•

Ta p

Gas Burner

Assembl

Main•

Orifices

Figure 2-18. Gas Valve

Adjustment Screw (5 mm)

for minimum pressure

setting

Adjustment Screw

(8 mm) for maximum

pressure

setting

F. Checkout

After any adjustment, set appliance in operation and observe
through a component cycle to ensure that burner system com­ponents function correctly.

G. Maintenance

It is recommended to check yearly the minimum and the maxi­mum setting and readjust them if necessary.

H. Connection

WARNING

Some procedures in this section may require

conversions, readjustments, or service on the oven's
gas system. Before performing these procedures, check
that the main gas supply valve and the circuit breaker/fused

=

disconnect are in the OFF ("O") position. After completing
these procedures, perform a gas leak test before operating
the oven.

CAUTION

The terms of the oven's warranty require all start-ups, conver­sions and service work to be performed by a Middleby Marshall
Authorized Service Agent. The installation, start-up and changes
required when changing from one gas type to another can be
performed ONLY by a certified professional.

NOTE: Certain safety code requirements exist for the installation
of gas ovens; refer to the beginning of Section 2 for a list of the
installation standards. In addition:

• In the USA, the installation must conform with local codes,

or in the absence of local codes, with the National Fuel Gas
Code, ANSI Z223.1.

• In Canada, the installation must conform with local codes,

or in the absence of local codes, with the Natural Gas
Installation Code, CAN/CGA-B 149.1, or the Propane
Installation Code, CAN/CGA-B 149.2, as applicable.

• In Australia, the installation must conform with AGA Codes

AG311 and AG601, and with any requirements of the
appropriate statutory authority.

• In CE countries, the gas supply connection should be

according to EN-203 (gas appliance directive) and to
applicable ISO 228-1 or ISO 7-1 recommendations. All
aspects of the gas supply connection must comply with
current IEC/CEE requirements and with all applicable
local, national, and international codes.

• For all ovens equipped with casters, the gas line connection

shall be made with:

- A connector that complies with the Standard for
Connectors for Movable Gas Appliances, ANSI Z21.69
(in USA), or Connectors for Movable Gas Appliances,
CAN/CGA-6.16 (in Canada).

Check the oven’s gas supply requirements to determine the
type of gas to be used with the oven. If the gas type required does
NOT match the local supply:

• For North American installations,

a conversion kit is
supplied with the oven to allow operation using propane
gas. Refer to Part B, Gas Conversion, in this section.

• For CE ovens, directions for converting the oven for use with
other gases are described in Part D.1,

Preparation for Use

with Various Gases, in this section.

16

If the installation will use the supplied gas hose, be sure that
the 1/2" to 3/4" gas line fitting is attached. Refer to the
instructions in the gas hose package. One gas line connection
method is shown in Figure 2-15; however, compliance with
the applicable standards and regulations is mandatory.

Inlet and regulated gas pressures can be measured using
a “U” tube manometer at the tap locations shown in Figures
2-15 and 2-16.

1. Checking the Gas Supply (Inlet) Pressure

a. With the main gas supply valve closed and the circuit

breaker/fused disconnect in the OFF ("O") position, open
the inlet pressure tap shown in Figure 2-16 and attach a

manometer to the tap.
b. Depress the safety switches to allow the oven to operate.
c. Open the main gas supply valve. Switch the circuit

breaker/fused disconnect to the ON ("I") position.
d. Start the oven according the directions in the

section of this Manual. Adjust the temperature controller

to the maximum setting (316°C).
e. Measure the supply (inlet) pressure.
f. Switch the oven off. Close the main gas supply valve, and

switch the circuit breaker/fused disconnect to the OFF

("O") position. Remove the manometer, and close the

inlet tap.
g. Compare the measured supply (inlet) pressure to the

nominal pressures shown in Table 1-5 (in the Description

section of this Manual).
If the supply pressure is lower or higher than the nominal

pressure, the reason should be investigated and the gas
supplier contacted.

For natural gas ovens, if the measured supply pressure is
lower than 0.247psi, or higher than 0.363psi, contact the gas
supplier. DO NOT OPERATE THE OVEN or adjust the oven
controls.

Operation

SECTION 2

INSTALLATION

17

SECTION 2
INSTALLATION

NOTES

18

I. CONTROL FUNCTIONS

SECTION 3

OPERATION

SECTION 3

OPERATION

Figure 3-1. PS520-Series Oven Control Functions

WARNING

A possibility of injury from rotating parts and
electric shock exists in this oven.
Never disassemble or clean the oven with the
BLOWER switch or any other oven control turned
“ON” or “I”. Turn “OFF” or “O” and lockout or
tagout all electric power to the oven before
attempting to clean or service this oven.

19

SECTION 3
OPERATION

II. COMPONENT INFORMATION AND

LOCATION (Figures 3-1 and 3-2)

A. Door Safety Switch

The Door Safety Switch is located at the lower right side
of control panel opening. Opening the control panel door
permits this switch to open, disconnecting power to all
electrical controls.

CAUTION

Do NOT touch the wires going to this safety switch.
Current is always present.

B. Blower Switch

The blower switch has two positions. The switch must
be “ON” or “I” for the main blowers to come on and permit
the oven to run. The fan circulates the air throughout the
oven and must stay on during baking and during the
cool down cycle above 200°F (93°C) to prevent blower
bearing damage. To protect the blower motor and
bearings a thermostatic override is built into the oven.

If the temperature inside the oven is over 180°F (82°C)
the main blower will continue to run after the blower
switch is turned to the “OFF” or “O” position.

C. Heat Switch

The “Heat Switch” allows the burner to activate. Activation
is determined by the settings on the Digital Temperature
Controller.

D. Temperature Controller

The temperature controller is a solid-state, PID type to
maintain the operator-set temperature. The temperature
controller continuously monitors the oven temperature and
turns on the modulating solid state relay controller. The
heat is on for the time required to maintain a constant oven
temperature.

The temperature controller contains a low-limit switch
which allows the oven to cool down to 200°F (93°C) before
shutting off the blower. A high-limit indication (ALM 1) will
appear on the display if the oven reaches 650°F (343°C).

Figure 3-2. Interior View of Control Console

20

E. Conveyor

The on-off switch for the conveyor motor is on the control
panel. Also on the control panel is the digital conveyor
speed control. The digital control can be adjusted
from 1-10 min. bake time (conveyor speed).
Refer to Figure 3-3.

Conveyor speed is measured by the amount of time it
takes for an item to go through the bake chamber of the
oven.

MEASURING CONVEYOR SPEED.

SECTION 3

OPERATION

See Figures 3-4 and 3-5.

To check conveyor speed, place a product item at the
entrance end of baking chamber as shown. Time how long
it takes for the leading edge of the item to go from the
entrance end of the baking chamber to the exit end. This
should be the conveyor speed shown on the conveyor
speed digital control.

NOTE: In Figures 3-4 and 3-5, the oven shown is with the
conveyor running right to left.

WARNING

Possibility of injury from rotating parts and

electrical shock exist in this oven.

Never disassemble or clean the oven with the

blower switch or any other part of the oven

turned “ON” or “I”. Turn “OFF” or “O” and

lockout or tagout all electrical power to the

oven before attempting to clean or service

this oven.

Figure 3-3. Conveyor Speed Digital Control

Figure 3-4. Product at entrance end of baking

chamber – BEGINNING OF TIMING

21

Figure 3-5. Product at exit end of baking

chamber – END OF TIMING

SECTION 3
OPERATION

WARNING

OVEN MUST BE KEPT CLEAR OF

COMBUSTIBLES AT ALL TIMES.

III. STEP-BY-STEP OPERATION

4. Set the temperature controller to the desired baking
temperature.

NOTE: For complete temperature controller operation
instructions refer to Step C.

5. Turn the HEAT switch (Figure 3-6) to the “ON” or “I”
position. Wait for the “Heat ON” light to turn on.

A. Startup Procedures

Daily Startup

1. Turn the BLOWER switch (Figure 3-6) to the “ON” or “I”
position. This starts the main blower fan and the cooling
fans. The blower circulates air through the air fingers and
must stay on during the cooking or baking process.

2. Check to see if the cooling fans (see Figure 1-8) are
operating when the blower switch (see Figure 3-6) is turned
“ON” or “I”. The cooling fans cool the control components
and blower motor. The cooling fans, located at the rear of
the oven blows air into and through the cabinet. Air is
exhausted through the front of the cabinet and also out the
front of the oven. Refer to Daily Maintenance Section for
fan intake checking procedure.

IMPORTANT NOTE

The cooling fan operates when the BLOWER
switch is turned “ON” or “I”. It must operate to keep
the control console below 140°F (60°C).

3. Turn the CONVEYOR switch (Figure 3-6) to the “ON” or
“I” position. This starts the conveyor belt moving through
the oven. Set the conveyor speed for the desired baking
time. Refer to the following Procedures E, F and G.

6. Oven will reach a baking temperature of 500°F (232°C)
in approximately 20 minutes. Allow the oven to cycle for
30 minutes after it has reached desired bake temperature.
The oven is now ready for baking.

Power Failure

In case of power failure, turn off all switches and remove
product. After power has been reestablished follow
normal startup procedure.

B. Shutdown Procedure

1. Turn the BLOWER and HEAT switches to “OFF” or “O”.

NOTE: The blowers will remain on until the oven tempera­ture cools down to 200°F (93°C) at which time they will stop
automatically.

2. Make certain that there are no products left on the
conveyor inside the oven. Turn the CONVEYOR switch
to “OFF” or “O”.

22

SECTION 3

OPERATION

Figure 3-6. Control Panel

23

SECTION 3
OPERATION

IV. NORMAL OPERATION - STEP-BY-STEP

A.Daily Startup Procedure

1. Check that the circuit breaker/fused disconnect is in the
on position.

2. Turn the "BLOWER"

( ) switch to the “ON”

("I") position.

3. Turn the "CONVEYOR"
( ) switch to the
“ON” ("I") position.

4. If necessary, adjust the
conveyor speed setting
by pressing the
pushbuttons on the con­veyor speed controller to
change the displayed
bake time.

or

or

7. Wait for the oven to heat to the setpoint temperature.
Higher setpoint temperatures will require a longer wait.
The oven can reach a temperature of 500°F (232°C) in
approximately 15 minutes.

8. (Optional) Press the Tem­perature (

the Actual Temperature
in the display, and wait
for the "ACTUAL TEMP"
light to turn on. This al­lows you to monitor the
oven temperature as it
rises to the setpoint.

9. Allow the oven to preheat for 10 minutes after it has
reached the set point temperature.

B. DAILY SHUTDOWN PROCEDURE

1. Turn the "HEAT" (
"BLOWER" (
ches to the "OFF" ("O")

position. Note that the
blowers will remain in op­eration until the oven has
cooled to below 200°F
(93°C).

) key to show

) and

) swit-

wait

for

+

5. Adjust the temperature
controller to a desired set
temperature, if neces­sary.

• Press the Set Point

and Unlock keys at
the same time. Wait
for the "SET PT" light
to turn on.

• Press the Up Arrow
and Down Arrow
Keys as necessary
to adjust the set­point.

6. Turn the "HEAT" ( )
switch to the "ON" ("I")
position, and wait for the
"HEAT ON" light to turn
on.

+

or

wait

for

wait

for

2. Make certain that there
are no products left on
the conveyor inside the
oven. Turn the "CON­VEYOR" (
the "OFF" ("O") position.

3. After the oven has cooled and the blowers have turned
to the “OFF” or “O” position, switch the circuit breaker/fuse
disconnect to the “OFF” or “O” position.

) switch to

IMPORTANT

On gas ovens, if the "HEAT ON" light will not illuminate,
OR if the oven does not heat, the gas burner may not have
lit. Turn the "HEAT" (
VEYOR" (
for AT LEAST FIVE MINUTES before restarting the oven.
Then, repeat the Daily Startup procedure.

) switches to the "OFF" ("O") position. Wait

), "BLOWER" ( ), and "CON-

CAUTION

In case of power failure, turn all switches to the “OFF”
("O") position and remove the product. After the
power has been restored, perform the normal startup
procedure. IF THE OVEN WAS SWITCHED OFF FOR
LESS THAN 5 MINUTES,
MINUTES BEFORE RESTARTING THE OVEN.

WAIT FOR AT LEAST FIVE

24

SECTION 3

OPERATION

"SP LOCK"

Light

Lights when the
set point is locked
out from changes.

This setting can

only be changed by

service personnel.

OVERTEMP

Light

Lights when the oven

temperature is

greater than 650°F

(343°C). Refer to

Quick Reference:

Troubleshooting in

this section.

Display

Shows the Set Point

or the Actual Tem-

perature in degrees

Fahrenheit (F) or

Celsius (C).

"HEAT ON"

Light

Lights when the

burner is in

operation.

"SET PT"
(setpoint)

Light

Lights when the

set point is shown

in the display.

"ACTUAL TEMP"

Light

Lights when the Actual
Temperature is shown

in the display.

Temperature

Key

Press this key once

to view the Actual

Temperature in the

Display.

together with the Set

Point Key to allow the

changed. Changes

can only be made for

Unlock Key

Press this key

Set Point to be

60 seconds.

Up Arrow and Down

Arrow Keys

Press these keys to

adjust the Set Point up or

down. If the Set Point will

not change, refer to Set

Point Key and Unlock Key

in this section.

Service Key

Service use

only.

Set Point Key

Press this key

together with the

Unlock Key to allow

the Set Point to be

changed.

Changes can only be

made for 60 sec-

onds.

25

SECTION 3
OPERATION

V. QUICK REFERENCE: TROUBLESHOOTING

SYMPTOM PROBLEM SOLUTION

light is lit, food product is

undercooked

Oven will not

turn on at all

appears in display,
oven is not heating

Oven will not heat

The oven temperature ex­ceeded 650°F (343°C), and
the burner was automati­cally shut down.

Electrical power may not be
reaching the oven, or the
controls may be set incor­rectly.

The oven did not reach
200°F (93°C) within 15 min­utes of startup, and the oven
has stopped heating.

Controls may be set incor­rectly.

• Follow the procedures under Daily Shutdown Procedures in
this section to shut down the oven. Contact your Middleby
Marshall Authorized Service Agent to determine and correct the
cause of the condition to prevent damage to the oven.

• Check that the circuit breaker/fused disconnect is turned on.

• Check that the "BLOWER"
position.

• Turn the "HEAT" (
( )switches to the "OFF" ("O") position.

• Wait for AT LEAST FIVE MINUTES before restarting the oven.

• Repeat the Daily Startup procedure.

• Check that the Set Point is correctly set.

• Check that both the "BLOWER"
are in the “ON” ("I") position.

• If the oven still will not heat,turn the "HEAT" ( ), "BLOWER"

( ), and "CONVEYOR" ( )switches to the "OFF" ("O")

position.

• Wait for AT LEAST FIVE MINUTES before restarting the oven.

• Repeat the Daily Startup procedure. Check that the Set Point
is above 200°F (93°C).

( ) Switch is in the “ON” ("I")

), "BLOWER" ( ), and "CONVEYOR"

( ) and "HEAT" ( ) Switches

Oven is operating, but

little or no air is blowing

from air fingers

Conveyor moves with a

jerky motion, or will not

move at all

Food products are

overcooked or

undercooked.

Air fingers may have been
reassembled incorrectly
after cleaning.

Conveyor may be jammed
on an object in the oven, or
conveyor belt or drive chain
tension may be incorrect.

Controls may be set incor­rectly.

• Turn the oven to the “OFF” or “O” position, and allow it to cool.
Disconnect electrical power to the oven.

• Refer to Section 4,
bling the air fingers.

• Turn the oven to the “OFF” or “O” position, and allow it to cool.
Disconnect electrical power to the oven.

• Check if the conveyor is blocked by an object inside the oven.

• Refer to Section 4,
the conveyor and drive chain tension.

• Check that the set temperature and bake time settings are
correct.

Maintenance, for instructions on reassem-

Maintenance, for instructions on checking

IF THESE STEPS FAIL TO RESOLVE THE PROBLEM, CONTACT YOUR LOCAL MIDDLEBY MARSHALL
AUTHORIZED SERVICE AGENT. A SERVICE AGENCY DIRECTORY IS SUPPLIED WITH YOUR OVEN.

26

SECTION 4

MAINTENANCE

SECTION 4

MAINTENANCE

WARNING

Before ANY cleaning or servicing of the oven, perform the following procedure:

1. Switch off the oven and allow it to cool. Do NOT service the oven while it is warm.

2. Turn the full-flow gas safety valve to the off position.

3. Turn off the electric supply circuit breaker(s) and disconnect the electric supply to the oven.

4. If it is necessary to move a gas oven for cleaning or servicing, disconnect the gas supply before moving the oven.
When all cleaning and servicing is complete:

1. If the oven was moved for servicing, return the oven to its
original location.

2. Reconnect the gas supply.

3. Reconnect the electrical supply.

WARNING

Possibility of injury from rotating parts and electrical

shock exist in this oven. Turn off and lockout or tagout

electrical supply to oven(s) before attempting to

disassemble, clean or service oven(s). Never disas-

semble or clean the oven with the blower switch or any

other part of the oven turned on.

WARNING

Before performing any maintenance work or cleaning,

turn main power switch off.

CAUTION

When cleaning do not use any abrasive cleaning

materials or water spray, wipe clean only. Never use a

water hose or pressurized steam cleaning equipment

when cleaning this oven.

4. Turn on the full-flow gas safety valve. Test the gas line
connections for leaks using approved leak test sub­stances or thick soap suds.

5. Turn on the electric supply circuit breaker(s).

6. Perform the normal startup procedure.

NOTICE

If the oven is to be removed from its installed location
for servicing, perform the following procedure:

1. Switch off the oven and allow it to cool. Do NOT
service the oven while it is warm.

2. Turn off main circuit breakers and disconnect
connector from oven.

3. Move oven to desired location for servicing.

4. When servicing is complete, move oven to original
location.

5. Adjust legs to level oven.

6. Connect electrical connectors to oven.

7. Turn on main circuit breakers.

8. Follow normal startup instructions.

27

SECTION 4
MAINTENANCE

I. MAINTENANCE - DAILY

A. Exterior

Everyday you should clean the outside of the oven with a
soft cloth and mild detergent.

WARNING

Never use a water hose or pressurized steam
cleaning equipment when cleaning the oven.

B. Cooling Fan

1. ONE COOLING FAN GRILLE AT THE REAR OF THE
OVEN MUST BE CLEANED DAILY - Clean grille with a
stiff nylon type brush.

2. Check the air intake of the cooling fan daily. The best
time to check is right after starting the oven.

IMPORTANT NOTE

The cooling fan operates when the blower switch
is turned to “ON” (“I”). It must operate to keep the
electrical control cabinet below 140°F (60°C).

D. Crumb Pans (Figure 4-2)

WARNING

Crumb pan is extremely hot while oven is
operating. Allow oven to cool before
removing crumb pan.

When the oven is cool remove and clean the crumb pan at
each end of the oven. Each crumb pan can be removed
by sliding it out, as shown in Figure 4-2. Reinstall the
crumb pans after cleaning.

WARNING

IF FAN BLADE IS NOT ROTATING, BROKEN,
OR FAN ASSEMBLY IS MISSING FROM MAIN
BLOWER MOTOR SHAFT, DO NOT OPERATE
OVEN. REPLACE COOLING FAN BLADE
BEFORE OPERATING OVEN. Serious damage
could be done to the burner blower motor and/or
solid-state electrical components if oven is
operated while cooling fan is not running or vent
grille is plugged.

3. Using a stiff nylon brush clean control compartment
vent grille.

C. Conveyor Belt (Figure 4-2)

Everyday, just after starting the oven, stand at the
unloading end of the conveyor, and with a brush, remove
food particles (crumbs, etc.) clinging to the conveyor belt,
brushing them into the crumb pan.

Figure 4-1. Oven Cooling Fans

Figure 4-2. Conveyor Belt and

Crumb Pan Cleaning

28

SECTION 4

MAINTENANCE

II. MAINTENANCE - MONTHLY

NOTE: The oven interior may require cleaning more
than once a month depending on the volume of
baking. To clean the interior, you have to disassemble
some parts of the oven.

When cleaning your Series PS520 Oven note the
following:

PRECAUTIONS-

1. Do not use excessive water or saturation of oven
insulation will occur.

2. Do not use a caustic oven cleaner or the aluminized
finger manifold surfaces will be severely damaged.

When cleaning your oven, first remove all heavy debris
with a vacuum cleaner. Use a damp cloth for light cleaning.
For heavier cleaning of baked on grease and carbon
deposits use a non-caustic cleaner that will not react with
the aluminized finger manifold surfaces.

You can order non-caustic cleaner from your local autho­rized Middleby Marshall Parts Distributor in the quantities
listed:

Part # Quantity

27170-0244 Case of Quarts (6)

27170-0246 Case of Gallons (4)

A. Removing Conveyor From Oven For Cleaning

1. Remove entry and exit trays.

2. Loosen (do not remove) two screws on housing guard.

3. Remove motor housing guard.

4. Lift conveyor and remove chain.

5. Lift other side of conveyor and push toward other side.

Figure 4-3.

29

SECTION 4
MAINTENANCE

6. Remove conveyor as shown.

Figure 4-4.

Figure 4-5.

Figure 4-6.

Figure 4-7.

CAUTION

Be careful not to bump the drive sprocket while

handling the conveyor, to avoid damaging the

drive shaft.

30

B. Air Fingers Disassembly For Cleaning

1. As the air fingers are removed use a felt pen to mark all
parts of the fingers. This includes the finger manifold, inner
plate and the outer plate (refer to Figure 1-9). If a blank or
choke plate is used, mark that plate also. Fingers are
marked in the order shown; as viewed from the front of the
oven. (The marks for an upper oven should be preceded
with a “U”, example UB1, UT2, etc.)

T1 T2 T3

B1 B2 B3

Standard Fingers

2. Slide blank plates straight out.

SECTION 4

MAINTENANCE

Figure 4-9.

4. With air fingers out, place them in an upright position to
remove the outer plate.

Figure 4-8.

3. Remove air fingers.

NOTE: Some oven users require a custom finger arrange­ment where the quantity of air fingers may vary.

You can remove top and bottom fingers and blank plates
from each or either end. It is highly recommended that
each finger be marked before removing so it is placed in
exactly the same position when reassembled
(refer to step 1).

5. Gently step on the lip of the finger and pull the outer
plate off.

Remove the air fingers, pull the finger at the back side - pull
straight out.

Figure 4-10.

31

SECTION 4
MAINTENANCE

6. To remove the inner plate, pull the plate out and then up.

Figure 4-11.

7. The outer finger plate is stainless and may be cleaned
by either soaking in a hot, strong detergent solution or
using a caustic cleaner. The conveyor belt can also be
cleaned in the same way.

C. Reassembly of Air Fingers

1. Air fingers are made up of one inner plate, one outer
plate and the finger housing manifold. Be sure to match up
the markings (T1, T2, T3, etc.) on all the parts of the air
fingers as you are reassembling.

Figure 4-14.

2. Reassemble the inner plate. Keep your fingers clear so
you won’t pinch them. The inner plate of a finger will only
go in one way because of its design.

Figure 4-12. Standard Lower Finger

3. Replace the outer plate by placing your hands flat on
the top of the plate and pushing down. Keep your fingers
clear so you won’t pinch them.

Figure 4-15.

Figure 4-13. Standard Upper Finger

32

4. Replace the air fingers by pushing in at the back side.
Remember to replace them according to the numbers
marked on them when they were removed. They must go
back in the same way they came out.

IMPORTANT: When inserting fingers the tab on
the outer plate must be in the groove as shown in
Figure 4-18. There is a blocking tab on the outside
of the groove which will prevent inserting the
finger in the groove if the outer plate is moved
away from the flange of the finger manifold.

SECTION 4

MAINTENANCE

Figure 4-16.

Extended Lip

Flange of
Finger Manifold

Tab on
Outer Plate

Tab on
Outer Plate

Figure 4-17.

33

SECTION 4
MAINTENANCE

5. Install fingers and blank plates correctly with edges
interlocked and no space between edges.

Top Finger

Tab on Outer Plate of Finger
Located in Groove

Top Finger

Incorrect - Too
Much Space

Blank Plate

Incorrect - Too
Much Space

Blank Plate

Tab on Outer Plate of Finger
Located in Groove

Top Finger

Tab on Outer Plate of Finger
Located in Groove

Correct ­Edges Overlap
Completely

Blank Plate

Figure 4-18.

34

D. Reinstall End Plugs

1. Reinstall lower end plug. Be sure to tighten the wing
screw on the end plug.

2. Reinstall conveyor.

3. Reinstall upper end plug. Be sure to tighten two wing
screws on the end plug.

SECTION 4

MAINTENANCE

Figure 4-19.

Figure 4-20.

35

SECTION 4
MAINTENANCE

E. Conveyor Reassembly Into Oven

1. Lift conveyor and position it in oven as shown.

NOTE: Conveyor may be inserted into either end of oven.
If it is to be installed from the non-drive end of the oven the
drive sprocket assembly must be removed as shown in
conveyor disassembly section.

Figure 4-21.

2. Reinstall the conveyor extension.

F. Checking Conveyor Belt Tension

WARNING

Oven conveyor belt must be cool when adjusting
belt. Do not adjust belt if HOT.

1. With the conveyor assembly in the oven, stand at one
end of conveyor and check tension by lifting the conveyor
belt at the center of the oven chamber opening. The belt
should not lift higher that 1″ to 2″ (75mm to 102mm).

2. If conveyor belt is still not under proper tension, an
entire link must be removed. Use the following procedure
“H. Conveyor Belt Link Removal” to remove a link. If
conveyor belt is under proper tension proceed directly to
“J. Attaching Drive Chain”.

Conveyor Extension

Figure 4-23.

Figure 4-22.

36

SECTION 4

MAINTENANCE

G. Conveyor Belt Link Removal

1. Using long nose pliers, an entire link can be removed
with the conveyor assembly either in or out of the oven.
Position master links at end of conveyor as shown in
Figure 4-24.

Master
Links

Figure 4-24.

4. Unhook the link to be removed.

5. Pull up on the belt link section and remove. Do not
discard the link removed as it may be used for making
spare master links.

NOTE: If a section of the conveyor belt is being replaced
it should be done now. Remove the links that need
replacing and use the section of conveyor belt furnished in
your installation kit to replace them.

2. Using long nose pliers, unhook master links at left end
of conveyor as shown in Figure 4-25.

Figure 4-25.

3. Remove the outside master links on the right and left
sides of the conveyor belt as shown in Figure 4-26.

Figure 4-27.

NOTE: Before connecting the inside master links, notice

that these links have a correct position (Figure 4-28). The
link at the right is in the correct (horns up) position for
inserting into the conveyor belt. The horns facing down are
in the incorrect position.

Correct
Position

Incorrect
Position

Figure 4-28.

Figure 4-26.

37

SECTION 4
MAINTENANCE

6. Reconnect the inside master links (Figure 4-29.)

Figure 4-29.

NOTE: The outside master links have right and left sides

to them. The right edge master link has an open hook
facing you as shown in Figure 4-30. This will match up with
the outer edges of the conveyor belt. Remember this hook
travels backwards on the conveyor.

Direction of travel

H. Attaching Drive Chain

1. If drive sprocket assembly was removed reassemble it
into the conveyor drive shaft. Be sure flat on end of drive
shaft aligns with set screw in conveyor shaft collar. Once
in place tighten 3/32″ set screw.

2. Lift conveyor and install drive chain to conveyor drive
sprocket and motor sprocket.

Figure 4-30.

7. Reconnect the outside master links.

8. Replace all parts removed from the oven.

Figure 4-32.

3. The angle plate located on the underside of the con­veyor must be against the lower end plug. This is true on
both sides of oven.

Crumb Pan

Mounting

Bracket

Lower End Plug

Figure 4-33.

Figure 4-31.

38

SECTION 4

MAINTENANCE

4. Reattach conveyor guard to control panel and secure
two screws.

Install both upper end plugs.

Figure 4-34.

III. MAINTENANCE - EVERY 3 MONTHS

A. Electrical Terminals

Open the control cabinet door by removing the three
screws from the control cabinet door. Tighten all electrical
control terminal screws including the electrical contactor
terminal screws as shown in Figure 4-35.

Figure 4-35.

B. Ventilation

Check that the air circulation throughout the oven is not
blocked and is working properly.

WARNING

Shut OFF all electrical power and lock/tag out the
switch before attempting maintenance work.

NOTE: It is recommended that the 3-month mainte­nance be performed by an authorized Middleby Marshall
technician.

IV. MAINTENANCE - EVERY 6 MONTHS

A. Check brushes on D.C. conveyor motor, when worn to
less than 1/10″ (2.4mm), replace the brushes.

B. Check your oven venting system.

C. Inspect and clean the burner nozzle and the spark
electrode assembly.

IMPORTANT NOTICES:

• Installation of replacement parts requiring access
to the interior of the oven is permitted only by an
authorized service technician.

• If there are any problems with the operation of the
oven, the authorized service technician must be
called.

• It is suggested to obtain a service contract with a
manufacturer’s authorized service technician.

39

SECTION 4
MAINTENANCE

KEY SPARE PARTS KIT

An oven can be purchased with a Key Spare Parts Kit
(Figure 4-36). (The kit can be purchased when the oven is
ordered, or later, from a Middleby Marshall Authorized
Parts Distributor). The kit contains many of the crucial

PS520-SERIES GAS OVEN KEY SPARE PARTS KIT (Figure 4-36)

ITEM PART NO. ENGLISH DESCRIPTION QUANTITY

1 28041-0011 Contactor, DP 25A 208/240V 1
2 58390 Motor, Conveyor Drive w/Magnet 1
3 60671 Board, Amplifier Signal, 4-20VDC 1
4 32108 XFMR, 240V PRI 24V 65VA SEC 1
5 33812-5 Thermocouple, Type “J” Shielded 2.50 x 120 3
6 33813 Filter, RFI 1
7 38185 Assembly, Pickup Sensor 1
8 41872 Transformer, 240V (P), 24V (S) 25VA 1

9 44696 Switch, Rotary and Mounting Adapter 3
10 44697 Block, Contact 3
11 45644 Breaker, Circuit 240V 1A 1

12 48455 Ignitor, Single Rod PS536
13 50239 Ignition, Spark Module 24VAC 50/60 Hz 1
14 60598 Switch, Air .13″ WC 1
15 50794 Relay, 240VAC 2P1S 1
16 47321 Control, Combo 4-20MA, Burst 1
17 58323 Controller, Digital w/o Dip Switch 1
18 60679 Valve, Gas Modulating 1
19 36451 Fan, Cooling 230VAC 295 CFM 1

20 50240 Ignition Cable, 25″ 1

21 59002 Inshot Burner 2

22 52244 Main Blower 2

parts that can reduce serious downtime and loss of
production, if a failure occurs.

Replacement parts for this kit can be purchased from your
Middleby Marshall Authorized Parts Distributor.

1

220

14

1

89

5

3

10 11

16

17

7

13

5

12

19

4

18

21

15

22

Figure 4-36.

40

SECTION 5

TROUBLESHOOTING

SECTION 5

TROUBLESHOOTING

PROBLEM:

PRODUCTS ARE OVERCOOKED

OR UNDERCOOKED

Check for correct

setting of conveyor

speed control.

Set the conveyor speed

control at correct setting.

Verify the food

preparation process.

If products still cook incorrectly,

call your Middleby Marshall

Service Agency.

setting on tempera-

Check for correct

ture controller.

Turn temperature

control to correct

setting.

PROBLEM:

OVEN BLOWER AND CONVEYOR OPER-

ATE, YET THE OVEN IS NOT HEATING

Reset the temperature controller

to a new setting (above 200°F),

after turning the BLOWER switch

to off for 30 seconds.

Start the oven again. If the oven still does not

heat, call your Middleby Marshall Service Agency.

PROBLEM:

CONVEYOR WILL NOT HOLD PROPER

SPEED OR WILL NOT RUN AT ALL

Check whether the conveyor is
jammed on something in oven.

PROBLEM:

OVEN DOES NOT HEAT

Check to see if both BLOWER
switch and HEAT switch are in

the “ON” or “I” position.

If oven does not heat, call your

Middleby Marshall Service Agency.

PROBLEM:

BLOWER MOTOR IS RUNNING, YET LITTLE

OR NO AIR BLOWS FROM AIR FINGERS

Air fingers reassembled incorrectly,

after cleaning.

Assemble air fingers correctly, after cleaning.

Refer to Section 4 procedure, or call your

Middleby Marshall Service Agency.

Check for proper tension of conveyor drive

chain and conveyor belt. Refer to Section 4 for

correct procedure.

Check that the conveyor

drive sprocket is tight.

If conveyor still does not run correctly, contact

your Middleby Marshall Service Agency.

PROBLEM:

OVEN DOES NOT TURN ON WHEN ITS

SWITCHES ARE TURNED ON

Check that all electric supply switches are set to

the “ON” or “I” position. Then, start the oven.

If oven still will not start, contact your Middleby

Marshall Service Agency.

41

SECTION 5
TROUBLESHOOTING

NOTES

42

ELECTRICAL SCHEMATICS

SECTION 6

ELECTRICAL SCHEMATICS

SECTION 6

59113D

43

Wiring Diagram, G208-240 50/60 GO, PS520G

WARNING

Improper installation, adjustment, alteration, service or maintenance

can cause property damage, injury or death. Read the installation,

operating and maintenance instructions thoroughly before

installing or servicing this equipment.

NOTICE

During the warranty period, ALL parts replacement and servicing should be performed by

your Middleby Marshall Authorized Service Agent. Service that is performed by parties

other than your Middleby Marshall Authorized Service Agent may void your warranty.

NOTICE

Using any parts other than genuine Middleby Marshall factory manufactured parts relieves

the manufacturer of all warranty and liability.

NOTICE

Middleby Marshall reserves the right to change specifications at any time.

Middleby is proud to support the Commercial Food Equipment
Service Association (CFESA). We recognize and applaud
CFESA's ongoing efforts to improve the quality of technical
service in the industry.

Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • [phone] • FAX [phone]

www.middleby.com