Pitco MGII SERVICE MANUAL
IMPORTANT FOR FUTURE REFERENCE
Please complete this information and retain this manual
for the life of the equipment:
Model #: ___________________________
Serial #: ___________________________
Date Purchased: ____________________
Service Manual
MGII: McDonald’s Full and Split Gas Fryers
with and without Filter
ENGLISH
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L22-236 Rev. 2 (06/11)
TO THE PURCHASER, OWNER AND STORE MANAGER
Please review these warnings prior to posting them in a prominent location for reference.
TO THE PURCHASER
Post in a prominent location the instructions to be followed
in the event that an operator smells gas. Obtain this
information from your local gas supplier.
WARNING
DO NOT store or use gasoline or other flammable vapors and
liquids in the vicinity of this or any other appliance.
WARNING
Improper installation, alteration, service or maintenance can
cause property damage, injury or death. Read the
installation, operating and maintenance instructions
thoroughly before installing or servicing this appliance.
WARNING
Installation, maintenance and repairs should be performe d
by a Pitco Authorized Service and Parts (ASAP) company
technician or other qualified personnel. Installation,
maintenance or repairs by unauthorized and unqualified
personnel will void the warranty.
WARNING
Installation and all connections must be made according to
national and local regulations and codes in force.
WARNING
During the warranty period if a customer elects to use a nonoriginal part or modifies an original part purchased from
Pitco and/or its Authorized Service and Parts (ASAP)
companies, this warranty will be void. In addition, Pitco and
its affiliates will not be liable for any claims, damages or
expenses incurred by the customer which arises directly or
indirectly, in whole or in part, due to the installation of any
modified part and/or received from an unauthorized ser vice
center.
WARNING
This appliance, when installed, must be electrically grounded
in accordance with local codes, or in the absence of local
codes, with the National Electrical Code, ANSI/NFPA 70, or
the Canadian Electrical Code, CSA C22.2, as applicable.
WARNING
Adequate means must be provided to limit the movement or
this appliance without depending on the gas or electrical
cord connection. Single appliances equipped with legs must
be stabilized by installing anchor straps. All appliances
equipped with casters must be stabilized by installing
restraining chains, or equivalent means.
WARNING
An appliance equipped with casters and a flexible gas line
must be connected to the gas supply with a quick disconnect
device. This quick disconnect must comply with ANSI Z24.41.
WARNING
DO NOT alter or remove structural material on the appliance
to accommodate placement under a ventilation hood.
WARNING
This appliance is intended for professional use only and
should be operated by fully trained and qualified personnel.
WARNING
If the appliance is equipped with a power cord and it is
damaged, it must be replaced by a Pitco Authorized Service
and Parts (ASAP) company technician, or a similarly
qualified person in order to avoid a hazard.
WARNING
The power supply must be disconnected before servicing,
maintaining or cleaning this appliance.
WARNING
The appliance is NOT jet stream approved. DO NOT clean
the appliance with a water jet.
WARNING
DO NOT attempt to move this appliance or transfer hot
liquids from one container to another when the unit is at
operating temperature or filled with hot liquids. Serious
personal injury could result if skin comes in contact with the
hot surfaces or liquids.
WARNING
DO NOT sit or stand on this appliance. The appliance’s front
panel, tank, splash back, tank cover, workshelf, drain board
is not a step. Serious injury could result from slipping,
falling or contact with hot liquids.
WARNING
NEVER use the appliance as a step for cleaning or accessing
the ventilation hood. Serious injury could result from slips,
trips or from contacting hot liquids.
WARNING
The oil/shortening level should NOT fall below the minimum
indicated level line at any time. The use of old shortening
can be dangerous as it will have a reduced flash point and be
more prone to surge boiling.
WARNING
The contents of the crumb catch and/or filter pan of any filter
system must be emptied into a fireproof container at the end
of each day. Some food particles can spontaneously
combust if left soaking in certain types of oil or shortening.
WARNING
Completely shut the appliance down when oil/shortening is
being drained from the appliance. This will prevent the
appliance from heating up during the draining and filling
process. Serious injury can occur.
WARNING
This appliance is intended for indoor use only.
WARNING
DO NOT operate appliance unless all panels and access
covers are attached correctly.
WARNING
It is recommended that this appliance be inspected by a
qualified service technician for proper performance and
operation on a yearly basis.
WARNING
There is an open flame inside this appliance. The unit may
get hot enough to set nearby materials on fire. Keep the area
around the appliance free from combustibles.
WARNING
DO NOT supply the appliance with a gas that is not indicated
on the data plate. If you need to convert the appliance to
another type of fuel, contact your Equipment Supplier or a
Pitco Authorized Service and Parts (ASAP) Company.
WARNING
DO NOT use an open flame to check for gas leaks!
WARNING
If gas flow to appliance is interrupted, or pilots extinguish,
wait 5 minutes before attempting to relight the pilot to allow
any residual gas in appliance to dissipate.
WARNING
Ensure that the appliance can get enough air to keep the
flame burning correctly. If the flame is starved for air, it can
give off a dangerous carbon monoxide gas. Carbon
monoxide is a clear odorless gas that can cause suffocation.
2 L22-236 Rev. 2 (06/11)
MGII Full and Split Tank Gas Fryer TABLE OF CONTENTS
1. THEORY OF OPERATION.....................................................................5
1.1. HEATING SYSTEM .....................................................................................................................................5
1.2. H
1.3. H
1.4. T
1.5. F
IGH LIMIT SYSTEM:.................................................................................................................................5
OOD RELAY SYSTEM - U.S./CANADA UNITS O NLY....................................................................................5
EMPERATURE PROBE..............................................................................................................................5
ILTER SYSTEM ........................................................................................................................................6
2. TROUBLESHOOTING ...........................................................................7
2.1. FRYER TROUBLESHOOTING.......................................................................................................................7
2.2. F
ILTER TROUBLESHOOTING.......................................................................................................................9
3. COMPONENT TROUBLESHOOTING.................................................10
3.1. TEMPERATURE PROBE:...........................................................................................................................10
3.2. G
3.3. H
3.4. D
3.5. T
3.6. I
3.7. R
AS VALVE:...........................................................................................................................................10
IGH LIMITS:..........................................................................................................................................11
RAIN VALVE & RETURN VALVE SWITCHES:............................................................................................11
RANSFORMER:......................................................................................................................................11
GNITION MODULE:..................................................................................................................................11
ELAY BOARD: ......................................................................................................................................12
3.8. C
3.9. F
OMPUTER CONTROLLER: ......................................................................................................................13
LUE BAFFLE .........................................................................................................................................14
4. CE GAS TABLE...................................................................................15
5. COMPONENT REPLACEMENT FRYER.............................................17
5.1. FRONT PANEL ........................................................................................................................................17
5.1.1. Front Panel Bezel................................................................................................................17
5.1.2. Computer Removal .............................................................................................................17
5.1.3. Wire Reduction Board.........................................................................................................17
5.1.4. Front Panel and Top Deck..................................................................................................18
5.2. C
ONTROL COMPONENTS .........................................................................................................................19
5.2.1. Ignition Module....................................................................................................................19
5.2.2. Transformer Box .................................................................................................................19
5.2.3. Transformer .........................................................................................................................20
5.2.4. Cord Entrance Box..............................................................................................................20
5.2.5. Hood Relay (North America Only).....................................................................................20
5.3. G
AS TRAIN.............................................................................................................................................21
L22-236 Rev. 2 (06/11) 3
TABLE OF CONTENTS
5.3.1. Manual Gas Shutoff.............................................................................................................21
5.3.2. Gas Valve Removal.............................................................................................................21
5.3.3. Pilot Removal.......................................................................................................................23
5.3.4. Burner Removal...................................................................................................................23
5.3.5. Gas Conversion...................................................................................................................24
5.4. T
ANK .....................................................................................................................................................25
5.4.1. Probe Replacement.............................................................................................................25
5.4.2. High Limit Replacement .....................................................................................................26
5.4.3. Drain Switch Removal.........................................................................................................26
5.4.4. Tank Removal......................................................................................................................27
5.4.5. Tank Disassembly...............................................................................................................29
5.4.6. Tank Assembly....................................................................................................................30
5.4.7. Tank Installation..................................................................................................................33
6. COMPONENT REPLACEMENT – FILTER..........................................36
6.1. PUMP AND PUMP BOX.............................................................................................................................36
6.1.1. Pump Removal.....................................................................................................................36
6.1.2. Pump Box.............................................................................................................................37
6.1.3. Pump Transformer ..............................................................................................................37
6.1.4. Pump Relay..........................................................................................................................37
6.1.5. Pump Circuit Breaker..........................................................................................................37
6.2. D
RAIN LINE ............................................................................................................................................38
6.2.1. Drain Line Removal.............................................................................................................38
7. SCHEMATICS......................................................................................39
7.1. CONTROL SCHEMATIC.............................................................................................................................39
7.2. F
7.3. F
7.4. C
7.5. C
7.6. C
4 L22-236 Rev. 2 (06/11)
ILTER SYSTEM 115V.............................................................................................................................40
ILTER SYSTEM 208, 220 – 240 V..........................................................................................................41
ORD BOX & HOOD CONTROL (US & CANADA) ......................................................................................42
ORD BOX W/O HOOD CONTROL (US & CANADA)...................................................................................42
ORD BOX (EXPORT & CE)....................................................................................................................43
MGII and MG2T GAS FRYER SERVICE
1. Theory of Operation
Knowing and understanding the MGII sequence of fryer and component operation will enable you to diagnose
equipment failure more easily and accurately. (Note: The schematic references used are derived from the
schematic on pages _ - _ of this manual.)
1.1. Heating System
Power to the machine is turned ON:
When the fryer is plugged in, power is supplied to the transformer, T1. The transformer step s the line
voltage down to 24VAC to operate the heat control circuit.
If Fuse, F1, on the Relay Board, A4, is good, the “AC POWER” LED illuminates. The computer is supplied
with 24VAC and, if the drain valve handle is closed, the proximity switch, LS1, supplies 24 VAC to the DVI
(drain valve interlock) Input at the Computer Controller, (reference connector J/P1, pin #5).
The Computer Controller, A1, is turned ON by pressing the
The Side On Relay, K3, will be energized, closing the circuit and the “S.O.” LED on the Relay Board
illuminates. If the High Limit, HL1, is NOT tripped the ignition module is supplied with 24VAC at terminal 6
(24VAC).
The ignition module generates a 24VAC output from terminal 3(PV) to the PV terminal on the Gas Valve,
V1, and generates a spark at the igniter, E2. When the pilot has lit and the ignition module has proven the
pilot flame, it will have a 24VAC output at terminal 1(MV) resulting in 24VAC at connector J/P32, pin #2, on
the Relay Board. The Heat Demand Relay, K1, on the Relay Board will control the 24VAC supply to the
gas valve when the controller calls for heat. Note: When the Computer Controller is on, the pilot should
always remain lit.
When the Computer Controller calls for heat:
The Heat Demand Relay is energized supplying the Gas Valve with 24VAC and the “HD” LED on the
Relay Board illuminates. This also supplies the Computer Controller with a heat feedback signal, at
connector J/P32, pin #6.
1.2. High Limit System:
If the High Limit, HL1, opens (“trips”), it interrupts the 24VAC supply to the ignition module. As a result, the
pilot goes out. When the Computer Controller calls for heat, it will not receive a 24VAC heat feedback
signal. After 10 seconds, (90 seconds on first heat demand), of heat demand output lacking a heat
feedback signal, the Computer Controller will indicate “IGNITION FAILURE” or “HEAT FAIL”. After the
High Limit is reset, (allow unit to cool below 400ºF, (204ºC), and press red reset button.), the Computer
Controller will have to be turned off and back on for the unit to heat.
button:
1.3. Hood Relay System - U.S./Canada units only
There is one Hood Relay, K6, per system, (“battery”) of fryers (located in a box mounted below the rear
bottom brace of left-hand fryer). It is wired in parallel to the Side On signal of every Computer Controller
(both sides of an MG2T Split). When any side of any Computer Controller is turned on this relay is
energized, (providing power to the hood fan motor) and will stay energized until all Computer Controllers
are turned off.
The Side On harness is equipped with a Fuse, F_. In the event of a short or over-current in the wiring to
the Hood Relay, all the F_ fuses in the system will blow. As a result, the fryer will no longer control the
hood fan motor. To repair, first correct the over-current condition, and then replace all the F_ fuses in the
fryer system.
1.4. Temperature Probe
The Computer Controller receives temperature readings from the Temperature Probe, RT1.
The Temperature Probe resistance varies with temperature, decreasing as temperature rises.
L22-236 Rev. 2 (06/11) 5
SERVICE
1.5. Filter System
Opening the RED filter return valve handle closes the magnetically actuated Proximity Switch, LS4,
causing the “Pump Run” Relay, K5, to be energized. This allows line voltage to flow to the Filter Pump
Motor, M1. The Pump Motor begins to run. Closing the filter return valve handle will de-energize the relay
and the Pump Motor will stop running.
The pump system is equipped with a Circuit Breaker, CB1, which de-energizes the system and the heat
tape, (if so equipped), in the event of over-current. The Circuit Breaker switch must be in the ON position
for the pump and heat tape to operate.
The return piping system may be provided with optional Heat Tape, HTR1, to prevent solidification of solid
shortening. The Heat Tape is low wattage and is on constantly to maintain liquid shortening in the line.
The Filter Pump Motor, M1, is equipped with a thermal overload. In the event of over-temperature of the
pump motor, the thermal overload opens shutting off the pump. Once the pump motor has cooled, it can
be reset by pressing the red button at the end of the motor housing.
6 L22-236 Rev. 2 (06/11)
MGII and MG2T GAS FRYER SERVICE
2. Troubleshooting
2.1. Fryer Troubleshooting
Problem Probable Causes Corrective Actions
No power to appliance. Check main building power supply.
Circuit Breaker tripped. Reset circuit breaker.
Connect power cord. Check power
cord where it enters the rear of the
Computer Controller
display does not light.
Power Cord loose or not connected.
Fuse, F1, blown.
Transformer, T1, Defective. Check and replace if defective
Defective Controller
Computer is in Melt Cycle. Allow time for unit to heat up.
fryer’s entrance box. Verify that it is
plugged all the way into the
receptacle.
Check Wire Reduction Board. If AC
Lamp is not lit check F1 fuse. If fuse
is blown, replace with a 2.5 A fast
acting fuse.
If AC Lamp on Wire Reduction
Board is lit, check for 24 VAC
between pins 1 and 2 on J/P 1. If
voltage is present and computer
display is not lit, controller is
defective. Check for shorts on
controller outputs prior to replacing
controller.
Computer Controller
shows “MELT” and
heats slowly, or not
at all.
Computer Controller
shows “IGNITION
FAILURE” and
alarms.
Main gas supply is off. Verify main gas supply is turned on.
Gas shut off valve (yellow handle) is
closed.
Gas valve is not turned on. Turn manual gas valve to “ON”.
Quick disconnect not properly
connected.
High temperature limit has tripped.
Ignition Module has locked out.
Low gas pressure
Main gas supply is off. Verify main gas supply is turned on.
Gas shut off valve (yellow handle) is
closed.
Gas valve is not turned on. Turn manual gas valve to “ON”.
Quick disconnect not properly
connected.
Verify gas shut-off valve is open,
(yellow handle is in line with the gas
line).
Verify quick disconnect is properly
seated.
Reset high temperature limit. Check
and replace if defective.
Turn Fryer off and back on again to
reset ignition module. If lockout
recurs, check for proper pilot flame
and proper module operation.
Replace if defective
Check regulated gas pressure at
burner manifold. Verify pressure
matches dataplate information.
Adjust as necessary.
Verify gas shut-off valve is open,
(yellow handle is in line with the gas
line).
Verify quick disconnect is properly
seated.
L22-236 Rev. 2 (06/11) 7
SERVICE
Problem Probable Causes Corrective Actions
Computer Controller
shows “IGNITION
FAILURE” and
alarms (cont.)
Excessive Recovery
Time; (Recovery
Time exceeds 2:25
Standard)
Oil Temperature is
hotter, or colder than
shown by Computer
Controller
Computer Controller
displays “DRAINING”
or “TURN OFF”
Computer Controller
displays “PROBE
FAILURE”
Allow appliance to cool and reset
High temperature limit has tripped.
Ignition Module has locked out.
Low gas pressure
Improper Flue Baffle Setting
Excessive Oil Level
Oil added during Recovery Test.
Quick disconnect not properly
connected.
Low gas pressure
Improper Flue Baffle Setting
Burners require cleaning. Remove and clean burners.
Temperature Calibration
Defective Temperature Probe
Blue drain valve is not completely
closed.
Improperly adjusted or defective
drain switch
Open or shorted temperature probe Check and replace if defective.
high temperature limit. Check and
replace if defective
Turn fryer off and back on again to
reset ignition module. If lockout
recurs, check for proper pilot flame
and module operation. Replace if
defective.
Check regulated gas pressure at
burner manifold. Verify pressure
matches dataplate information.
Adjust as necessary.
Adjust flue baffle to provide proper
burner operation.
Oil level should never exceed “MAX”
line. Drain extra oil from tank.
Repeat heat up without adding oil
during test and compare results.
Verify quick disconnect is properly
seated.
Check regulated gas pressure at
burner manifold. Verify pressure
matches dataplate information.
Adjust as necessary.
Adjust flue baffle to provide proper
burner operation.
Refer to McDonald’s PM Card
FR014.
Contact a qualified service
technician.
Close blue drain valve handle.
Check and Adjust/Replace as
needed.
8 L22-236 Rev. 2 (06/11)
MGII and MG2T GAS FRYER SERVICE
2.2. Filter Troubleshooting
Drain valve is not fully open Press down on the drain
valve handle and verify that it
is fully open
Drain Valve is open; the oil is
draining slowly or not at all
Drain is plugged with debris. Use the clean out rod to clear
the drain valve opening. If this
does not clear the blockage,
close the drain valve.
Remove drain “T” to clear
blockage.
Red return valve handle is not
completely open.
Pull on the red return valve
handle to make sure it is
completely open.
Pump return handle is pulled
out, but no pumping sound
can be heard.
Filter circuit breaker is tripped
or in the off position.
Filter motor thermal overload
is tripped.
Filter power cord is
unplugged or loose.
Reset the circuit breaker or
press it to the on position.
Push the red reset button on
the end of the filter pump
motor.
Check the power cord at the
rear of the fryer entrance box,
and at the rear of the pump
box and verify that the power
cords are pushed all the way
into their receptacles.
Loose or defective sensor
switch
Check that the switch is tight
and has the correct gap.
Replace if defective.
Dirty filter media Change filter paper/pad.
Pickup tube screen clogged Remove and clean pickup
Oil is returning to the tank
slowly or not at all.
Filter pan not pushed in
completely
O-rings not sealing on pickup
tube.
tube screen cap.
Push filter pan in to complete
connection.
Check and replace o-rings if
defective.
Pickup tube screen not tight. Tighten pickup tube screen
cap.
Excessive air bubbles are in
the oil being returned to the
tank.
Drain valve is closed, but the
computer controller still
displays “DRAINING”
Pickup tube screen cap
missing
Filter pan not pushed in
completely
O-rings not sealing on pickup
tube.
Blue drain valve handle not
completely closed
Improperly adjusted or
defective drain switch.
Locate and install pickup tube
screen cap.
Push filter pan in to complete
connection.
Check and replace o-rings if
defective.
Verify that drain valve handle
is completely closed.
Check that the switch is tight
and has the correct gap.
Replace if defective.
L22-236 Rev. 2 (06/11) 9
SERVICE
A
3. Component Troubleshooting
3.1. Temperature Probe:
Electrical resistance of the Temperature Probe, RT1, changes as the
temperature changes. As temperature rises, the probe’s resistance
decreases.
If the probe is suspect, check its resistance and the oil/air temperature at
which it was taken. Compare these values to those in the table at right.
If the probe measures open circuit, (O.L. or ) or shorted, (0 Ohms), it
should be replaced. If the resistance varies more than 30 Ohms when
being checked between 325-375F, (163-190C), the probe will give a
false temperature reading to the computer controller and should be
calibrated (up to 10F) or replaced.
3.2. Gas Valve:
The Gas Valve, VI has dual 24VAC valve coils. When 24VAC is applied to
the PV connection, the pilot valve opens, allowing gas to flow to the pilot.
When 24VAC is applied to the MV connection, the main valve opens,
allowing gas to flow to the main burners.
TEMP RESISTANCE TEMP RESISTANCE
°F/°C
60/16 139,055 330/166 1,192
80/27 84,644 335/168 1,123
100/38 53,146 340/171 1,058
120/49 34,328 345/174 998
140/60 22,755 350/177 942
160/71 15,446 355/179 890
180/82 10,716 360/182 841
200/93 7,586 365/185 795
210/99 6,427 370/188 752
220/104 5,470 375/191 712
240/116 4,013 380/193 675
260/127 2,991 385/196 640
280/138 2,262 390/199 607
300/149 1,734 395/202 576
320/160 1,347 400/204 547
325/163 1,267
OHM
°F/°C
OHM
Pilot flame is adjustable using the pilot adjustment screw. It should be
adjusted at installation to achieve a flame sense current of 0.15 A or
greater.
Note: This procedure requires the use of a DC microammeter. The
meter should be wired with a switch that allows the meter to be
switched out of the circuit while the ignition system is sparking.
Connect the DC microammeter between the flame sensor (spark) terminal
and the flame sensor lead, (spark cable). Once the pilot is lit, and sparking
has stopped, switch the meter into the circuit. Observe proper polarity: if
the meter needle goes below 0, reverse the leads. The flame current
reading must be 1.0 A or greater, (0.15 A or greater for CE units).
Remove the pilot adjustment screw cap screw, (B), to expose the pilot
adjustment screw. Turning the pilot adjustment screw clockwise
decreases the size of the pilot flame and flame sense current. Turning the
pilot adjustment screw counterclockwise increases the pilot flame size and
the flame sense current. Once the pilot flame has been adjusted properly,
replace the pilot adjustment screw cap screw and remove the
microammeter.
The gas valve is equipped with a pressure regulator to
regulate burner pressure. Regulated pressure should be
the same, ±0.1” W.C. (.25mbar, .02kPa), as that marked
on the data plate on the inside door of the appliance. To
measure regulated gas pressure, connect an accurate
pressure gauge (range of 0-16 “W.C. (0-39.85mbar, 0-
3.98kPa) in 0.1” (.25mbar, .02kPa) increments) or
manometer to the burner pressure tap, (A). To adjust the
pressure, remove the burner pressure regulator
adjustment screw cap and, with a flat head screwdriver,
adjust the regulator screw until the proper burner
Model Gas Type Gas Pressure (in W.C.)
MG2 #46 #55 4.0 10.0
MG2S #46 #55 4.0 10.0
Orifice Tip Size and Burner Pressure
(for CE Countries see Section 4.0)
ON
OFF
) Burner Pressure Tap
B) Pilot Adjustment Screw Cap
C) ON/OFF Knob
D) Burner Pressure Regulator Adjustment
Screw Cap
E) Inlet Pressure Tap
NON-CE COUNTRIES
Nat LP Nat LP
10 L22-236 Rev. 2 (06/11)
MGII and MG2T GAS FRYER SERVICE
g g
pressure is reached. Turning the screw clockwise will increase the burner pressure. Turning the screw
counterclockwise will decrease the burner pressure. When the pressure is correct, replace the regulator
adjustment screw cap.
NOTE: A properly sized and installed gas line will deliver a minimum supply pressure of 7.0”
W.C. (17.4mbars, 1.74kPa) natural gas or 13.0” W.C. (32.4mbars, 3.25kPa) propane to all
appliances connected to the supply line, operating simultaneously at full demand. If regulated
gas pressure cannot be achieved with all appliances in the store running, there may be a
buildin
as supply deficiency.
3.3. High Limits:
The High Limit switch, HL1, is a normally closed switch that opens when the temperature at the high limit
sensing bulb reaches 450F15F, (232C 8).
The high limit can be tested by utilizing the Computer Controller high limit test feature. Refer to McDonald’s
PM Card FR015 for instructions on how to perform this test.
WARNING!
This test should be performed by a qualified technician only! Monitor the fryer closely. This test will
cause the oil to heat past the normal operating temperature and can cause damage to the machine and
its operator if care is not taken.
WARNING!
This test will cause the burners to run continuously.
If the switch does not open, (“trip”), between the prescribed limits it is defective and should be replaced. Once
tripped, the switch cannot be reset until the oil has cooled to approximately 400F, (204C). If the switch
cannot be reset, (by pressing the red reset button), after the oil has cooled it is defective.
3.4. Drain Valve & Return Valve Switches:
These switches, LS1 and LS4, are magnetically actuated proximity switches.
When the Drain Valve Handle is moved to the open position, the Actuator magnet will move away from the
switch causing the Drain Valve Switch, LS1, to open. When the Drain Valve is closed the switch will close.
Opening the Red Return Valve Handle will close the proximity switch causing the “Pump Run” Relay, K5, to be
energized. The pump will begin to pump. Closing the return valve handle will open the proximity switch
causing the relay to de-energize and the pump will stop pumping. These switche s can be checked with an
Ohmmeter. When the switch is closed, you should have continuity, (near 0 Ohms). The normal gap between
the Actuator magnet on the valve handle and the Sensor switch is
1
/8” – ¼” (3 – 6mm).
3.5. Transformer:
The Transformer, T1, is a Class 2 step-down, multiple tap primary to 24VAC secondary device. The
transformer can be checked by reading the input and output voltages. A quick check for transformer 24VAC
output can be done at the relay board behind the front panel. The AC LED is illuminated if the F1 fuse is good
and the board is receiving 24 VAC at connector J/P35 between pins #2 and #4.
3.6. Ignition Module:
The Ignition Module, A2, is a 24VAC input, single ignition trial, (with multiple retrials upon flame loss), device. It
senses flame through the spark lead using flame rectification. When 24VAC is input between the 24V (THS on
CE modules) terminal and 24V (GND), the ignition module generates a 24VAC output from its PV terminal.
The igniter sparks until the module senses pilot flame, or for 85-90 seconds, at which time the module will lock
out, whichever occurs first. When the module has proven the pilot flame, it will generate a 24VAC output at the
MV terminal resulting in 24VAC at connector J/P32, pin #2 on the relay board. (The relay board then controls
the 24VAC to the gas valve when the Computer Controller calls for heat.)
L22-236 Rev. 2 (06/11) 11
SERVICE
Note: When the Computer Controller is on, the pilot should always remain lit. If the pilot is not lit, either the
high limit is open, or the ignition module has locked out. Ignition module lockout can be reset by turning the
fryer off and back on again.
3.7. Relay Board:
The relays on the relay board have 24VDC coils. They are soldered to the board and are non-repairable.
In the event of a relay failure, replace the relay board
When installed, the relay board must have fish paper installed between it and the heat shield to which it is
mounted. This prevents the leads on the board from shorting against the metal heat shield.
Relay Board Component Explanation:
Fuse:
F1 – If fuse is blown, AC will not be lit.
Trouble Shooting Lights:
A.C. – When lit, F1 Fuse and T1 Transformer are good.
S.O. – When lit, A1 Computer is on and K3 Side On Relay should be energized.
H.D. – When lit, A1 Computer is on and calling for heat, K1 Heat Demand Relay should be energized.
Relays:
K1 – Heat Demand Relay, will be energized when A1 Computer calls for heat and wh en H.D. is lit.
K3 – Side On Relay, will be energized when A1 Computer is on and A.C. is lit.
Connectors:
J31 – Connects to A1 Computer.
J32 – To Side On and Heat Demand Contactors and Heat Feed Back.
J33 – To 24 VAC jumper harness.
J34 – To Drain Switch.
J35 – Input voltage from transformer.
Relay Board:
Note: J connectors are marked on the relay board.
With 24 VAC supplied to pin #2 at connector J35 and a good
F1 fuse, the relay board will have a 24 VAC output at pin #2 on
connectors J33 and J34 and the A.C. indicator will be
illuminated.
Note: Since the fryer is equipped with a computer, at
connection J33 there will be a jumper from pin #2 to pin
#10 to supply 24 VAC to pin #2 at connection J31 to supply
the controller with 24 VAC.
When the board receives a 24 VDC side on input at pin #7 on
connectors J31 and J33, the S.O. indicator will illuminate, the
side on relay (S.O.) will energize and there will be a 24 VAC
output at pin #4 on connector J32.
When the board receives a 24 VDC heat demand input at pin
#6 on connectors J31 or J33, the H.D. indicator will illuminate,
the heat demand relay (H.D.) will energized and there should
be continuity between pin #1 and pin #2 at connector J32.
12 L22-236 Rev. 2 (06/11)
MGII and MG2T GAS FRYER SERVICE
3.8. Computer Controller:
The McDonald’s Computer controller is an electronic temperature control, timer and menu control. Input
signals to the controller, (Power, DVI, Heat Feedback) are 24VAC. Controller outputs, (Side On, Heat
Demand), are 24VDC. Temperature is measured via a thermistor temperature probe, RT1.
The same controller is used for McDonald’s Gas and Electric Fryers and for both Full and Split Tanks. When
the controller is powered up, it looks at probe and drain valve inputs to determine if it is a full or split
configuration. (For this reason, always connect the right harness first and then the left harness when
connecting a Split, as power comes into the controller via the left harness.)
Note: When replacing a controller, it must be set up for the appliance type, (GAS, GAS2 or ELECTRIC) on
which it is installed. The MGII fryer uses the GAS2 temperature algorithm. Failure to set the control up for
the correct appliance type may result in poor appliance operation.
Note: All controller test points are at connector P/J1 (closest connector to the controlle r).
With 24 VAC supplied to pin #1 (24 VAC supply) and pin #5 (24 VAC input from DVI), the display should
read “OFF”.
With the controller turned on, there will be a 24 VDC output at pin #9 (side on).
When the controller calls for heat, there will be a 24 VDC output at pin #8 (heat demand) and a 24 VAC
input at pin #6 (heat feed back). If the controller does not receive the 24VAC input at pin #6 within 10
seconds, (90 seconds on first heat demand), the controller will display “HEAT FAIL” or “IGNITION
FAILURE”. This indicates that the controller did not receive a heat feedback signal when it called for heat.
If this occurs:
Look to see if the pilot is lit. If not:
1. Check the high-limit switch, HL1. (Is it open (“tripped”)?)
2. Check the ignition module, A2, (Sensing pilot flame? locked out?).
If the pilot is lit:
3. Check the heat demand (HD) relay, K1, on the relay board; (Is heat demand relay energized?
Continuity through COM and NO contacts?).
If display reads “PROBE”, check the resistance of the temperature probe, RT1. See the table on page 5.
Check the wires and connectors between the probe and controller for continuity.
If display reads “SYSTEM” “FAILURE”, or “HOT HI-1”, test the temperature probe and the wires and
connectors between the probe and controller for a short.
If display reads “DRAINING” “TURN OFF”, this indicates that there is no 24VAC input at pin # 5, (DVI
Input). Verify that the drain valve is closed, check the proximity switch on the drain valve, turn the fryer off,
then turn the fryer on.
L22-236 Rev. 2 (06/11) 13
SERVICE
3.9. Flue Baffle
The McDonald’s MGII Gas Fryers are typically installed in a direct-coupled ventilation hood. They a re shipped
from the factory with adjustable baffles installed in the flue of each fryer. Upon installation, these baffles must
be adjusted to provide proper operation within the ventilation hood.
WARNING
Failure to properly adjust the flue baffles may result in improper operation, poor temperature
recovery, poor ignition, pilot extinction, and damage to the appliance.
If the appliance is not installed in a direct-coupled hood system, (e.g. canopy hood), the flue
baffles must be removed before installation for proper operation.
The fryer will ship with the baffle set in the normal position for most
McDonald’s “Universal” hoods. (McDonald’s direct-coupled hoods
manufactured after 1995 are of the “Universal” type.) If upon installation
under the hood, the burner flame is found to be lifting or pulsing, the draw of
the hood may be higher than nominal and adjustment of the flue baffle may
be necessary. The flame can be viewed by looking through the burner shield.
If the flue baffle requires adjustment, pulsing can often be heard when the
burners fire.
The baffle can be adjusted as follows:
1. Pull the fryer out from under the ventilation hood.
2. Loosen the 2 screws securing the baffle slide plate, move the plate to a
more closed position and retighten the screws.
3. Reinstall fryer under ventilation hood.
4. Recheck burner operation
5. Repeat as necessary
The burners should be rechecked after baffle adjustment. If there is pulsing or the flame is lifting off the burner
face, the baffle is still too far open. If there is significant flame roll out on ignition, then the baffle is too far
closed. The baffle should be set in the most open position that allows for stable, non-pulsing, non-lifting burner
operation.
WARNING!
If the baffle can not be adjusted properly, the facility must have the ventilation system checked
immediately to be sure that it is within normal operating specifications. After the ventilation system is
corrected, the baffle setting must be rechecked. Failure to correct ventilation problems or properly set
flue baffles will result in extremely poor fryer operation and possible equipment damage.
14 L22-236 Rev. 2 (06/11)
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