The warranty is NOT VALID unless the oven is installed, started, and demon-
strated under the supervision of a factory-authorized installer
NOTICE
Contact your authorized Service Agency to perform maintenance and
repairs. A Service Agency Directory is supplied with your oven.
NOTICE
Using any parts other than genuine Middleby Marshall factory-manufactured
parts relieves the manufacturer of all warranty and liability.
NOTICE
Middleby Marshall (Manufacturer) reserves the right to change specifications
at any time.
KEEP THIS MANUAL IN A VISIBLE LOCATION NEAR THE
OVEN FOR FUTURE REFERENCE.
ii
Page 3
Model No.________________________ Serial No._______________ Installation Date __________
MIDDLEBY MARSHALL
No Quibble Limited Warranty
(U.S.A. Only)
Middelby Marshall, Hereinafter referred to as “The Seller”,
warrants equipment manufactures by it to be free from defects
in materials and workmanship for which it is responsible. The
seller’s obligation under thus 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 purchase of (1) 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 no quibble 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 and Hawaii. The
warranty is valid in the 50 Unites 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 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.
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 forgoing 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
The Mideleby Marshall PS520-Series may be used
either as a single oven or stacked for use as a 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, single ovens. A triple oven
(Figure 1-3) consists of three stacked single ovens.
The lower oven is mounted on a base pad.
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.
SECTION 1
DESCRIPTION
Figure 1-1. Single PS520 Oven
Figure 1-2. Double PS520 Oven
Figure 1-3. Triple PS520 Oven
1
Page 6
SECTION 1
DESCRIPTION
PS520 SERIES OVEN SPECIFICATIONS
Conveyor Belt Width18.00” (457mm)
Heating Zone Length20.00” (5098mm)
Baking Area Square Feet2.5 sq ft (.023 sq. m.)
Overall Dimensions
Standard Single Oven w/Legs42.00” (1067mm) L x
35.21” (894mm) W x
21.72” (786mm) H x
Overall Dimensions
Double Oven42.00” (1067mm) L x
35.21” (894mm) W x
37.27” (947mm) H x
Overall dimensions
Triple Oven42.00” (1067mm) L x
35.21” (894mm) W x
52.82” (1342mm) H x
Weight of Single Oven250 lbs (93.3kg)
Shipping Weight325 lbs (121.3kg)
Operating Range8.3 kW/hr
Maximum Operating temperature5500F (2870C)
Warm-up Time20 min.
Belt Speed Limits1-10 minutes
SERIES PS520 ELECTRICAL SPECIFICATIONS
Main Blower &Control CircuitPhaseFrequencyAmperagePolesWires
Elements VoltageVoltageDraw
All Models208-240V208-240V1 Ph50/60 HzSee Below2 Pole3 Wire
CE Only380-400V230-240V1 Ph50/60 HzSee Below2 Pole3 Wire
Heater Amperage(2 hot, 1 grd)
VoltagekWAmp
3808.321.8
4008.323.0
3 Ph50/60 HzSee Below4 Pole5 Wire
Heater Amperage(3 hot, 1 neut, 1 grd)
Voltage kWL1L2L3 N
3808.3 21.8 21.8 1.2 1.2
4009.2 23.0 23.0 1.2 1.2
(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.
This Manual Must Be Kept For Future Reference
2
Page 7
II. COMPONENT FUNCTION
SECTION 1
DESCRIPTION
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 1 minute to 10 minutes; this
is the time that a product can take to pass trough 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. Electric Heaters
There is one heater element mounted on the inside of
the rear panel. The element is connected to an electrical
control which is energized by the temperature controller.
D. Cooling Fan - See Figure 1-4
Blower Motor
Stand off
Cooling Fan
Figure 1-4 Blower Assembly
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 4-8, 414
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 it’s holes aligned with the holes of the
outer plate.
3. Manifold - the Manifold is the assembly which slides
on the tracks into the oven plenum.
Conveyor Drive Motor
Left Control Box
Figure 1-5 Machinery Compartment
Components
3
Page 8
SECTION 2
INSTALLATION
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 provide 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” (112mm) Long x
37-1/2” (953mm) Wide x
23” (584mm) High x
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.
CAUTION
On ovens with the Machinery Drive
Compartment located at the RIGHT end, a
minimum clearance of 0” to a left side wall,
18” to a right side wall and 6” from a back wall
to air openings at the rear of the oven must be
maintained.
For servicing and cleaning, a minimum of 18”
clearance from all walls is recommended.
4
Page 9
PARTS LIST FOR SERIES PS520 ELECTRIC OVEN
INSTALLATION KIT
Single and Double Stack Ovens
P/N 48397
Item
NO.QTYPART NO.DESCRIPTION
143101908Leg 4” AD FT
2248392Insulation Bottom Tray
3148394Bottom Tray Weldment
4148396Top cover
5451387Screw MSSLT Thread 8-32 x 1/2, 18-8
6152358Installation & Operation Manual - English
6159476Installation & Operation Manual - French
SECTION 2
INSTALLATION
PARTS LIST FOR SERIES PS520 ELECTRIC OVEN
INSTALLATION KIT
Triple Stack Ovens
P/N 54593
Item
NO.QTYPART NO.DESCRIPTION
1248392Insulation Bottom Tray
2148394Bottom Tray Weldment
3148396Top cover
4451387Screw MSSLT Thread 8-32 x 1/2, 18-8
54M3828Pin, Alignment
6152358Installation & Operation Manual - English
6159476Installation & Operation Manual - French
5
Page 10
SECTION 2
INSTALLATION
Figure 2-5. MODEL PS520 SINGLE OVEN DIMENSIONS
1
The Opening Height is Adjustable
from 2-1/4 inch minimum to 3-3/4
inch maximum in 1/2 inch
increments.
Figure 2-6. MODEL PS520 DOUBLE OVEN DIMENSIONS
Figure 2-7. MODEL PS520 TRIPLE OVEN DIMENSIONS
6
Page 11
UTILITY ROUGH-IN DIMENSIONS AND POSITIONING
FOR PS520 SERIES OVENS
WARNING
DO NOT USE CONDUIT OR GAS LINE FOR
GROUNDING CONNECTION
CAUTION
IT IS RECOMMENDED THAT THE OVEN BE
PLACED UNDER A VENTILATION HOOD
FOR ADEQUATE AIR SUPPLY AND
VENTILATION
SECTION 2
INSTALLATION
To Oven
ELECTRIC SUPPLY TO BE
PROVIDED BY CUSTOMER
CIRCUIT BREAKER
Separate circuit breaker with lockout/tagout electrical
shutoff for each oven. Wire each oven separately.
50 amp circuit breaker for 208-240V, or 30 Amp circuit
breaker for 380-480V.
ELECTRICAL SPECIFICATIONS
ALL MODELS:
•208V main blower motors and elements, 1 Ph, 39.9
Amp draw, 50/60 Hz, 208V control circuit, 2 pole,
3 wire system per oven (2 hot, 1 grd).
•230V main blower motors and elements, 1 Ph, 33.0
Amp draw, 50/60 Hz, 230V control circuit, 2 pole,
3 wire system per oven (2 hot, 1 grd).
•240V main blower motors and elements, 1 Ph, 34.6
Amp draw, 50/60 Hz, 208-240V control circuit, 2 pole,
3 wire system per oven (2 hot, 1 grd).
•400V elements, 3 Ph, 23.0/23.0/1.2 Amp draw, 50/60
Hz, 5 pole, 4 wire system per oven (3 hot, 1 neut, 1
grd)
Do NOT use conduit for ground.
To Oven
Suggested dimensions are shown; utility code
requirements supercede any factors shown.
Figure 2-9. Typical PS520-Series Oven(s)
Installation
ELECTRICAL RATING
7.6 - 9.2 kW/hr
SUPPLY WIRING
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
A mechanically driven ventilation system is required for
the PS520 Series Middleby Marshall conveyorized electric
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 that must be installed in the field (See Section
1: Figure 1-4, page 3 for reference)
7
Page 12
SECTION 2
INSTALLATION
These “C” Channel brackets are installed in the vertical
plane using existing screws 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 connection for the ventilation
system, electric supply, as arranged by the
customer. Following these connections, the
factory-authorized installer can perform the
initial start-up 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.
A fused disconnect switch or a main circuit breaker
(customer supplied) 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 code requirements. Copper is the
recommended material for the electrical supply
conductors.
IV. ELECTRIC SUPPLY FOR ELECTRICALLY
HEATED OVENS
Power requirements for electrically heated ovens are
usually 208-240VAC, 1-phase, 3 wire (2 ‘hot’, 1 ground),
although ovens built for export can have power
requirements of 380VAC and 480VAC. (These ovens
have a 4-wire or 5-wire system.) A 1.5” (38mm) diameter
cutout/hole in the back of the machinery compartment
provides access for the electrical supply connections on
380V and 480V units. 208V and 240V units have 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.
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.
The supply conductors must be of the size and material
(copper) recommended to provide the current require;
(refer to the data plate for the ampere specifications).
Typical specifications for each PS520-Series Oven are
208-240V, 1-phase, 3 wire, 8.3kW; this oven requires
50 ampere service. A PS520-Series Double Oven (Figure
1-2) installation would require two 50 ampere service
connections, one for each oven; the 8.3kW power
consumption also doubles for such an installation to
16.6kW.
The 208V, 230V or 240V AC electrically heated oven
uses two legs of the supplied power to provide 208V,
230V or 240V AC power for the oven control circuitry
ELECTRICAL
INLET
Figure 2-10. Typical Electric Oven Data Plate
Figure 2-11. Junction Connection Box
8
Page 13
I. CONTROL FUNCTIONS
SECTION 3
OPERATION
SECTION 3
OPERATION
Temperature
Controller
Conveyor
Speed
Control
Conveyor
Switch
Blower
Switch
Heat
Switch
Figure 3-1. PS520-Series Oven Control Functions
WARNING
A possibility of injury from rotating parts and electric
shock exists in the 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 the oven.
9
Page 14
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 the 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
bearing damage. To protect the blower motor and
bearings a thermostatic override is built into the oven.
0
F (930C) to prevent blower
Temperature
Controller
If the temperature of the oven is over 2000F (930C) the
main blower will continue to run after the blower switch
is turned to the “OFF” or “O” position.
C. Heat Switch
Turning the HEAT switch to “ON” or “I” will energize the
electric heating system. This switch is in series with the
blower fan motor and high temperature override switch.
Both switches must be closed before the heating
elements can be energized.
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
consistent oven temperature.
The temperature controller contains a low-limit switch
which allows the oven to cool down to 200
0
F (930C)
before shutting off the blower. A high-limit indication
(ALM1) will appear on the display if the oven reaches
6500F (3430C).
Door Safety
Switch
Conveyor Speed
Digital Control
Conveyor Speed
Control Module
Conveyor
Drive Motor
Figure 3-2. Interior View of Control Console
10
Page 15
E. Conveyor
The on-off switch for the conveyor motor is on the
digital control panel. Also on the control panel is the
digital conveyor speed control. The digital control can
be adjusted from 1-10 minutes 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.
SECTION 3
OPERATION
MEASURING CONVEYOR SPEED
See Figure 3-4 and 3-5.
To check conveyor speed, place a product item at the
entrance end of the 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 Figure 3-4 and 3-5, the oven shown is with
the conveyor running left to right.
WARNING
A possibility of injury from rotating parts and electric
shock exists in the 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 the oven.
Minutes
Seconds
Figure 3-3. Conveyor Speed Digital Control
Figure 3-4. Product at entrance end of baking
chamber - BEGINNING OF TIMING
11
Figure 3-5. Product at exit end of baking
chamber - END OF TIMING
Page 16
SECTION 3
OPERATION
WARNING
OVEN MUST BE KEPT CLEAR OF
COMBUSTIBLES AT ALL TIMES
III. STEP-BY-STEP OPERATION
A. Start-up Procedure
Daily Start-up
1. Turn the BLOWER switch (Figure 3-6) to the “ON” or “I”
position. This starts the main blower fan and the cooling
fans. This 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 4-1 page
13) 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 NOTICE
The cooling fan operates when the BLOWER
switch is turned “ON” or “I”. It must operate to
keep the control console below 1400F (600C)
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 (see Figure 3-6) to the “ON” or “I”
position. This completes a circuit to supply electric power
to the electric heating system.
6. Oven will reach baking temperature of 500
approximately 20 minutes. Allow the oven to cycle for 30
minutes after it has reached desired baking 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
start-up 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 2000F (930C) at which time they
will stop automatically.
0
F (2320C) in
3. Turn the CONVEYOR switch (see Figure 3-6) to the
“ON” or “I” position. This starts the conveyor belt moving
through the oven. Set the conveyer speed for the desired
baking time. Refer to the following Procedures E, F and G.
2. Make certain that there are no products left on the
conveyor inside the oven. Turn the CONVEYOR switch to
“OFF” or “O”
12
Figure 3-6. Control Panel
Page 17
SECTION 3
OPERATION
IV. NORMAL OPERATION - STEP-BY-STEP
A. Daily Start-up Procedure
1.Check that the circuit breaker/fused disconnect is in the on
position.
2.Turn the “BLOWER”
switch to the “ON”
or “I” position.
3.Turn the “CONVEYOR”
switch to the “ON” or
“I” position.
4.If necessary, adjust the
conveyor speed setting
by pressing the
pushbuttons on the con-
veyor speed controller to
change the displayed
bake time.
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.
or
7.Wait for the oven to heat to the setpoint temperature.
Higher setpoint temperatures will require a longer wait.
The oven cavity can reach a temperature of 500
in approximately 15 minutes.
8.(Optional) Press the
Temperature key to
show 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.
0
F (2320C)
B. DAILY SHUTDOWN PROCEDURE
1.Turn the “HEAT”
and “BLOWER”
switches to the “OFF” or
“O” position. Note the
blowers will remain in
operation until the oven
has cooled to below
2000F (930C).
2.Make certain that there
are no products left on the
conveyor inside the oven.
Turn the “CONVEYOR”
switch to the “OFF”
or “O” position.
3. After the oven has cooled and the blowers have turned
off, switch the circuit breakers/fused disconnect to the
“OFF” or “O” position.
6. Turn the “HEAT”
switch to the “ON” or “I”
position, and wait for the
“HEAT ON” light to turn
on.
CAUTION
In case of power failure, turn all switches to the “OFF” or
“O” position and remove the product. After the power has
been restored, perform the normal start-up procedure. IF
THE OVEN WAS SWITCHED OFF FOR LESS THAN (5)
FIVE MINUTES, WAIT FOR AT LEAST (5) FIVE
MINUTES BEFORE RESTARTING THE OVEN.
13
Page 18
SECTION 3
OPERATION
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
6500F (3430C). Refer to
Quick Reference;
Troubleshooting in this
section.
Temperature
Key
Press this key once to view
the Actual Temperature in
the Display
Display
Shows the Set Point or
the Actual Temperature
in degrees Fahrenheit (F)
or Celsius (C).
“HEAT ON”
Light
Lights when the burner is
in operation.“SP LOCK”
“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.
Service Key
Service use only
Unlock Key
Press this key together
with the Set Point Key to
allow the Set Point to be
changed. Changes can
only be made for 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
14
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
seconds.
Page 19
V. QUICK REFERENCE: TROUBLESHOOTING
SYMPTOMPROBLEMSOLUTION
SECTION 3
OPERATION
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
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
0
200
utes of start-up, and the
oven has stopped heating.
Controls may be set incorrectly
0
F (3430C), and
F (930F) within 15 min-
•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” , “BLOWER” , and
“CONVEYOR” switches to the “OFF” or “O” position.
•Wait for AT LEAST FIVE MINUTES before restarting the
oven.
•Repeat the daily procedure.
•Check that the Set Point is correctly set.
•Check that both “BLOWER” and “HEAT”
switches are in the “ON” or “I” position.
•Wait for AT LEAST FIVE MINUTES before restarting the
oven.
•Repeat the Daily Start-up procedure. Check that the Set
Point is above 2000F (930C)
Switch is in the “ON” or “I”
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 to
cool. Disconnect electrical power to the oven.
•Refer to Section 4, Maintenance, for instructions on
reassembling the air fingers.
•Turn the oven to the “OFF” or “O” position, and allow to
cool. Disconnect electrical power to the oven.
•Check if the conveyor is blocked by an object inside the
oven.
•Refer to Section 4, Maintenance, for instructions on
checking the conveyor and drive chain tension.
•Check that the set temperature and bake time settings
are correct.
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.
15
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SECTION 4
MAINTENANCE
SECTION 4
MAINTENANCE
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
disassemble 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.
NOTICE
If the oven is to be removed from it’s 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 breaker.
8. Follow normal start-up instructions.
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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 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” or “I”. It must operate to keep
the electrical control cabinet below 140
0
F (600C).
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 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.
Cooling Fan Grille
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
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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 PS520-Series Oven note the following:
PRECAUTIONS-
1. Do not use excessive water or saturation of oven
insulation will occur.
2. Do not use 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
Console
Controls
Temperature
Controller
Removable Air Fingers
(inside baking chamber)
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 below
Part#Quantity
27170-0244Case of Quarts (6)
27170-0246Case 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.
Blower and Cooling
Fan Motor
Conveyor
Speed
Control
Conveyor
Motor
(inside)
Motor
Housing
Guard
Removable
Crumb Pan
Removable
Conveyor
Assembly
Adjustable
Eyebrow
Legs
Figure 4-3
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SECTION 4
MAINTENANCE
5. Lift other side of conveyor and push toward other
side.
6. Remove conveyor as shown.
Figure 4-4
Figure 4-5
Figure 4-6
Figure 4-7
CAUTION
19
Be careful no to bump the drive sprocket while
handling the conveyor, to avoid damaging the
drive shaft.
Page 24
SECTION 4
MAINTENANCE
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 (see 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.)
Standard Fingers
2. Slide blank plates straight out.
Figure 4-8
Figure 4-9
3. Remove air fingers.
NOTE: Some oven users require a custom finger
arrangement where the quantity of air fingers may vary.
You can remove the 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).
4. With air fingers out, place them in an upright position
to remove the outer plate.
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 sidepull straight out.
Figure 4-10
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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 steel 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 parts of
the air fingers as you are reassembling.
Figure 4-14
Figure 4-12. Standard Lower Finger
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.
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 4-13. Standard Upper Finger
Figure 4-15
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SECTION 4
MAINTENANCE
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.
Figure 4-16
Extended Lip
Flange of
Finger Manifold
Tab on
Outer Plate
Tab on
Outer Plate
Figure 4-17
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MAINTENANCE
5. Install fingers and blank plates correctly with edges interlocked and no space between edges.
SECTION 4
Top Finger
Tab on Outer Plate of
Finger Located in Groove
Correct -
Edges Overlap
Completely
Figure 4-18
D. Reinstall End Plugs
1. Reinstall lower end plug. Be sure to tighten the wing screw on the end plug.
2. Reinstall conveyor.
Blank Plate
3. Reinstall upper end plug. Be sure to tighten two wing screws on the end plug..
Figure 4-19
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SECTION 4
MAINTENANCE
E. Conveyor Reassembly Into Oven
1. Lift conveyor and position it in the oven as shown.
NOTE: Conveyor may be inserted into either end of
the oven. If it is ti 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 the conveyor and check tension by lifting
the conveyor belt at the center of the oven chamber
opening (see Figure 4-23). The belt should not lift
higher then 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”.
3. Newer model PS520-Series ovens have adjustment
screws at the end to tighten the conveyor belt. If these
adjustment screws are at their limit and belt tension is
still not correct, loosen the adjustment screws,
proceed to “H. Conveyor Belt Link Removal” to
shorten the belt and then return to “F. CheckingConveyor Belt Tension” for proper adjustment. If belt
is tensioned properly proceed directly to “J. AttachingDrive Chain”.
Conveyor Extension
Figure 4-22
Figure 4-23
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Page 29
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 the end of the
conveyor as shown in Figure 4-24.
Master
Links
Figure 4-24
2. Using long nose pliers, unhook master links at left
end of conveyor as shown in Figure 4-25.
4. Unhook the link to be removed.
5. Pull up on the link section and remove. Do not
discard the link removed as it may be used for making
spare master links.
NOT: If a section of the conveyor is being replaced it
should be done now. Remove the links that need
replacing and use the section of conveyor belt
furnished in the installation kit to replace them.
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
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SECTION 4
MAINTENANCE
6. Reconnecting 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.
H. Attaching Drive Chain
1. If drive sprocket assembly was removed,
reassemble it onto 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 the oven.
Crumb Pan
Mounting Bracket
Lower End Plug
Figure 4-33
Figure 4-31
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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 as shown in Figure 4-
35.
Figure 4-35
B. Ventilation
WARNING
Shut OFF all electrical power and lockout/tagout
the switch before attempting maintenance work.
NOTE: It is recommended that the 3-month
maintenance be performed by an authorized Middleby
Marshall technician.
Check that the air circulation throughout the oven is
not blocked and is working properly.
IV. MAINTENANCE - EVERY 6 MONTHS
A. Check brushes on D.C. conveyor motor. When
worn to less then 1/10” (2.4mm), replace the brushes.
B. Check your venting system.
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.
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SECTION 4
MAINTENANCE
PS520-SERIES ELECTRIC OVEN KEY SPARE PARTS KIT
ITEMPART NO.DESCRIPTIONQUANTITY
158504Kit, Temperature Control On/Off PID1
251402Relay, 100A1
358390Conveyor Drive Motor with 2 pole magnet1
458323Conveyor Speed control1
533812-5Thermocouple3
650715Heater Element, 208V1
651017Heater Element, 240V1
651958Heater Element, 380V1
651961Heater Element, 480V1
757408Contactor 65 amp 3-pole1
28
Page 33
SECTION 5
TROUBLESHOOTING
SECTION 5
TROUBLESHOOTING
PROBLEM:
PRODUCTS ARE OVERCOOKED
OR UNDERCOOKED
Check for correctCheck for correct
setting of conveyorsetting on temperature
speed control.controller
Set the conveyorTurn temperature
speed control atcontrol to correct
correct setting.setting.
Verify the food
preparation process.
If products still cook incorrectly,
call your Middleby Marshall
Service Agency.
PROBLEM:
OVEN BLOWER AND CONVEYOR OPERATE,
YET THE OVEN IS NOT HEATING
Reset the temperature controller
to a new setting (above 2000F),
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 the 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