Marshall Air F12G Service Manual
This document contains the installation and
operating instructions for:
MODELS: F12G AUTOBROIL™&
F12G DUAL BELT AUTOBROIL™
FOR YOUR SAFETY
DO NOT STORE OR USE GASOLINE OR OTHER
FLAMMABLE VAPORS OR LIQUIDS IN THE
VICINITY OF THIS OR ANY OTHER APPLIANCE.
INSTRUCTIONS TO PURCHASER:
1. ANSI Z83.11 STANDARDS REQUIRE THAT YOU POST IN A PROMINENT
LOCATION THE PROCEDURES TO FOLLOW IN THE EVENT THE USER
SMELLS GAS. THIS INFORMATION SHALL BE OBTAINED FROM THE
LOCAL GAS SUPPLIER.
2. THIS MANUAL NEEDS TO BE RETAINED FOR FUTURE REFERENCE.
WARNING: IMPROPER INSTALLATION, ADJUSTMENT, ALTERATION, OR MAINTENANCE CAN CAUSE
PROPERTY DAMAGE, INJURY OR DEATH. READ THE INSTALLATION, OPERATION AND MAINTENANCE
INSTRUCTIONS THOROUGHLY BEFORE INSTALLING OR SERVICING THIS EQUIPMENT.
111838 RV121898
Copyright © 1994 Marshall Air Systems, Inc.
All Rights Reserved.
MODEL: F12G
TABLE OF CONTENTS
I. MACHINE SETTINGS (Quick Reference)..................................................................... 2
II. MACHINE INSTALLATION............................................................................................. 3
III. OPERATING INSTRUCTIONS ...................................................................................... 6
IV. SCHEDULED MAINTENANCE...................................................................................... 7
V. PREVENTIVE MAINTENANCE...................................................................................... 8
VI. TROUBLESHOOTING................................................................................................... 9-11
VII. ASSEMBLY & DISASSEMBLY INSTRUCTIONS ......................................................... 12
VIII. REPLACEMENT PARTS............................................................................................... 13-16
Pre-lnstallation ....................................................................................................... 3
Appliance Location................................................................................................. 3
Electrical Information............................................................................................. 4
Gas Piping To Appliance ....................................................................................... 4
Pre-Operation Check............................................................................................. 4
Lighting Instructions................................................................................................ 5
Shut-Off Instructions.............................................................................................. 5
Performance Criteria.............................................................................................. 5-6
BROILER LIMITED WARRANTY.................................................................................... i
BROILER WARRANTY PROCEDURES........................................................................ ii
ILLUSTRATIONS
F12G Broiler Overall Dimensions............................................................................. FIGURE 1
Gas Components & Conveyor Drive (Rod Style)..................................................... FIGURE 2
Conveyor Drive (Mesh Style).................................................................................... FIGURE 2A
Conveyor Travel (Rod Style)..................................................................................... FIGURES
Conveyor Belt (Mesh Style)...................................................................................... FIGURE 3A
Bearing, Sprocket and Motor.................................................................................... FIGURE 4
Control Cabinet Front................................................................................................ FIGURES
Control Cabinet Components................................................................................... FIGURES
Circuit Board - Speed Control................................................................................... FIGURE 7
Thermocouple Location............................................................................................ FIGURES
Burner Assembly....................................................................................................... FIGURE 9
Tunnel Assembly....................................................................................................... FIGURE 10
Gas Piping ................................................................................................................. FIGURE 11
Gas Restraining Device............................................................................................. FIGURE 12
Hang-On Parts........................................................................................................... FIGURE 13
Lower Shield Removal.............................................................................................. FIGURE 14
Gas Line Illustration................................................................................................... FIGURE 15
Circuit Board Asby with Mount.................................................................................. FIGURE 16
Schematic.................................................................................................................. 111831
Schematic.................................................................................................................. 114464
I. MACHINE SETTINGS
AUTOBROIL™
F12G
SERIAL NUMBER: ________________________________________________________________________________
TYPE OF GAS: ___________________________________________________________________________________
HIGH LOW
GAS PRESSURE: ________ ________
CONVEYOR SPEED SETTINGS: ___________________________
TEMPERATURE SETTING: ___________________________
START-UP TECHNICIAN: _________________________________________________________________________
START-UP DATE: ________________________________________________________________________________
COMMENTS: ___________________________________________________________________________________
_______________________________________________________________________________________
________________________________________________________________________________________
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II. MACHINE INSTALLATION
PRE-INSTALLATION
1. After uncrating the Autobroil™ unit, inspect for shipping damage. Check that all control knobs are intact on the
electrical cabinet front. Contact the factory if there are obvious problems. Set the Autobroil™ in place and use the
plastic wrapping to protect it from the debris and trash of building construction. DO NOT remove plug from gas inlet
pipe. Leave this for the Qualified Service Company. Check that machine has not been dented or damaged by the
carrier. If damaged, notify your freight carrier immediately to file a concealed damage claim, following the
instructions attached to the outside of the shipping crate. Your warranty will not cover freight damage.
2. Installation must be performed by a Qualified Service Company. The term "Qualified Service Company" means any
individual, firm, corporation or company which either is engaged in and is responsible for the installation or
replacement of gas piping on the outlet side of the meter, or the service regulator when a meter is not provided, or
the connection, installation or repair of gas appliances, who is experienced in such work, familiar with all precautions
required, and has complied with all the requirements of the authority having jurisdiction.
3. A remote gas shut-off valve must be provided and interlocked to exhaust system when in operation.
4. Because this unit is power fan exhausted, it is necessary to provide adequate make up air equal to the amount
removed. In addition to this, any other exhausts, flues, or air removal systems must be taken into consideration.
Examples of this are heat removal fans or hot water heater flues.
5. The appliance and its individual shut-off valve must be disconnected from the gas supply piping system during any
pressure testing of that system attest pressures in excess of 1/2 psig (3.45 kPa).
6. The appliance must be isolated from the gas supply piping system by closing its individual shut-off valve during any
pressure testing of the gas supply piping system at test pressures equal to or less than 1/2 psig (3.45 kPa).
APPLIANCE LOCATION
1. Position Autobroil™ to properly align with exhaust hood. Note name plate clearance.
2. The hood/ventilator for the appliance should be located in accordance with the National Fire Protection Association
Standard #96, "Removal of Smoke and Grease-Laden Vapors from Commercial Cooking Equipment" and any local
applicable requirements.
3. For proper installation, the minimum clearance from combustible construction is 9" from sides and 9" from back.
4. Adequate clearance should be maintained to allow easy access to loading and unloading areas of the machine.
5. For servicing, unit must be moved 2' clear from all construction.
CAUTION: KEEP THE APPLIANCE AREA FREE AND CLEAR FROM COMBUSTIBLES.
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ELECTRICAL INFORMATION
1. The appliance is cord connected and requires a 120 volt, AC, 60 HZ, Single Phase, 3 wire w/ground 15 AMP circuit.
Appliance must be electrically grounded in accordance with local codes, or in the absence of local codes, with the
National Electrical Code ANSI/NFPA No. 70-1987, latest edition.
2. There is a Wiring Diagram located in the Owner's Manual and under the cover of the electrical control cabinet.
GAS PIPING TO APPLIANCE
1. Installation of this appliance must conform with local codes, or in the absence of local codes, with the National Fuel
Gas Code, ANSI #Z-223.1, latest edition.
2. In Canada, this appliance is to be installed in accordance with Standard CGA B149.1 or B149.2 Installation Codes
for gas burning appliances and equipment and any local applicable requirements.
3. The appliance is supplied with a 1/2" male pipe thread. The installer must make the pipe connection to the unit in
accordance with the "National Fuel Gas Code," ANSI Z-223.1, latest edition. The gas line connected to the 1/2" male
pipe thread cannot be less than a 1/2" pipe. The gas pressure and gas volume required by this appliance is shown
on Page 7. Gas piping from source to broiler must be adequate to satisfy these requirements when all other gas
appliances in the restaurant are operating at maximum demand. A 1/2" X 3/4" bushing is provided with machine to
accommodate 3/4" feed line.
4. A flexible AGA approved gas line is available. Instructions are (1) the installation shall be made with a connector that
complies with the Standard for Connectors for Movable Gas Appliances, ANSI Z21.69, latest edition, and a quickdisconnect device that complies with the Standard for Quick-Disconnect Devices for Use With Gas Fuel, ANSI
Z21.41, latest edition, and (2) adequate means must be provided to limit the movement of the appliance without
depending on the connector and the quick-disconnect device or its associated piping to limit the appliance
movement (see Figure 12 for details and Page 14, Item 4).
5. See Page 4, Items 5 and 6, for instructions on gas supply line pressure testing.
CAUTION: DO NOT OBSTRUCT THE FLOW OF COMBUSTION AND VENTILATION AIR.
PRE-OPERATION CHECK
Before lighting and operating your Autobroil™, make a quick check of critical items as follows:
1. Remove protective paper from outside covers and trays.
2. Remove side panel and check to see that all parts are in place and that none are damaged.
3. Start the conveyor chain and check for proper operation. The conveyor chain should run free and not be catching or
hanging up on anything.
4. The speed of the conveyor chain should be modulated from seven (7) minutes to thirty (30) seconds, and back again
without the chain stopping.
5. Check that gas pressure at appliance is correct (see Performance Criteria) (Page 7).
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LIGHTING INSTRUCTIONS
1. Turn exhaust system on.
2. Make sure filters are in place in the hood.
3. Turn conveyor chain on.
4. Remove side covers.
5. Turn gas cock in gas line on.
6. Turn knob on gas valve to on (see Figure 11).
7. Turn on heat switch. Ignition is electronic.
8. If pilot flame or burners fail to light turn heat switch off and wait five minutes before attempting to relight.
SHUT-OFF INSTRUCTIONS
1. Turn heat switch off.
2. Turn conveyor switch off.
3. Turn ventilator off.
PROLONGED POWER FAILURE: NO ATTEMPT SHOULD BE MADE TO OPERATE THE APPLIANCE DURING
POWER FAILURE.
PERFORMANCE CRITERIA - NATURAL GAS
1. The manifold pressure for each burner and appliance inlet pressure and gas amount is listed below:
TYPE OF GAS - Natural
PRESSURE AT THE APPLIANCE - 5.5 -10.0 IWC for Natural
MANIFOLD PRESSURE - Low 2.0 IWC; High 5.0 IWC for Natural
TOTAL GAS AMOUNT - 50,000 BTUH @ 100% High Fire
Manifold pressure is measured by a pressure gauge on the outlet side of the gas valve. With the unit on for at
least fifteen minutes and the broiler temperature controller set at 600°F, the pressure should be at 2.0 IWC. Now
set the broiler temperature controller to high and note that high fire pressure is 5.0 IWC. These valves are factory
set. If high pressure settings do not come up to specification, check for at least 5.5" line supply pressure. Refer to
Figure 11 - information is shown on gas pressure high and low range adjustment.
2. The burners in the appliance are a special infrared type. All of the air for combustion must be injected through the
Venturis. This makes orifice design and alignment very critical. The orifice design, in combination with the correct
natural or propane gas pressure will result in adequate air aspiration and mixing. There are no air shutters. No air
adjustment is needed.
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CAUTION: DO NOT STACK BOXES OR IN ANY WAY BLOCK AREA IN IMMEDIATE VICINITY OF VENTURIS
3. Pilot burner adjustment may be made by turning the pilot adjusting screw counter-clockwise to increase, or clockwise
to decrease flame size. Pilot adjusting screw is on gas valve (see Figure 11).
4. All burners will be bright orange when burning properly and with the temperature control set to cause 5.0 IWC (i.e.,
high fire) gas pressure on the pressure gauge. A dull red is normal once the set temperature is achieved. "Popping"
or burning back at the orifice of the burner is a result of the burner grid being loose or broken, or a faulty gasket
under the burner grid.
OR IN ANY OTHER WAY OBSTRUCT FLOW OF COMBUSTION AIR. THE TOP OF THE OVEN IS
VERY HOT.
- FIRE WARNING –
FLAMES WILL EXIT FLUE AREA AND COOKING CHAMBER ENDS DURING COOKING
NOTE: IF BURNER IS CRACKED OR BROKEN, OR IF A GASKET IS LEAKING, THE BURNER MUST BE
REPAIRED (see Figure 9).
III. OPERATING INSTRUCTIONS
1. After the power has been turned on, cycle the conveyor ON switch and observe that conveyor is moving and not
catching or hanging up on anything. The speed of the conveyor chain should be modulated from low to high, and
back again without the chain stopping. Leave the heat switch OFF.
2. The conveyor time selector controls for each conveyor can be set from 30 seconds to 7 minutes 59 seconds. This is
the time your food is in the oven as measured from the leading edge of the food starting IN the oven to the leading
edge starting OUT of the oven.
3. When the conveyor switch is turned on the temperature display indicates the temperature of the burners. The display
will read the approximate room temperature if the heat ON switch has not yet been turned ON.
LIGHTING INSTRUCTIONS
1. Turn exhaust system on.
2. Make sure filters are in place in the hood.
3. Turn conveyor chain on.
4. Remove side covers.
5. Turn gas cock in gas line on.
6. Turn knob on gas valve to on (see Figure 11).
7. Turn on heat switch. Ignition is electronic.
8. If pilot flame or burners fail to light turn heat switch off and wait five minutes before attempting to re-light.
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SHUT-OFF INSTRUCTIONS
1. Turn heat switch off.
2. Turn conveyor switch off.
3. Turn ventilator off.
4. With the heat switch ON, the display will indicate the temperature of the burners. The "SET" temperature is that which
is displayed by the pointer of the large knob. The ACTUAL temperature is shown in the window. Allow 20 minutes for
warm up in the morning. Your Operations Department has established speed settings for each conveyor, and generally
these should not be touched unless authorized by Operations. The combination of cooking time and temperatures
have been made to produce your food correctly.
5. The selectors for temperature and time may be adjusted should menu changes take place. CAUTION:
ONLY AUTHORIZED PERSONNEL SHOULD HAVE ACCESS TO THE ADJUSTABLE CONTROLS
PROLONGED POWER FAILURE: NO ATTEMPT SHOULD BE MADE TO OPERATE THE APPLIANCE DURING
POWER FAILURE.
IV. SCHEDULED MAINTENANCE
DAILY CLEANING PROCEDURES
CAUTION: DO NOT USE OVEN CLEANER ON THIS APPLIANCE. Under no circumstances should oven
cleaner ever be used on this appliance. IT WILL EAT HOLES IN THE ALUMINUM GAS VALVES
AND GAS LINES, CAUSTIC FUMES WILL CAUSE ELECTRICAL COMPONENT DAMAGE, AND WILL
CAUSE MANY OTHER PROBLEMS IF USED TO CLEAN THIS BROILER.
WARNING: THE REVERBERATING SCREEN (LOCATED UNDER THE TOP BURNERS), IS MADE FROM
INCONEL METAL MESH. THIS MATERIAL DETERIORATES WITH USE. INSPECT SCREEN DAILY
AND REPLACE IF SCREEN IS SEVERELY CORRODED. FAILURE TO DO SO CAN RESULT IN
METAL PARTICLES BEING SERVED TO YOUR CUSTOMERS.
CAUTION: Do not touch the broiler section immediately after appliance shut-down. The temperature inside
enclosures is in excess of 500°, which eliminates the need to clean any parts inside the enclosures for
sanitary purposes. Any grease that may build up on the exterior of the enclosures should be cleaned off
with a damp cloth and a minimum amount of detergent.
* Never use a large amount of water on the enclosure!!
CAUTION: KEEP THE APPLIANCE AREA FREE AND CLEAR FROM COMBUSTIBLES.
1. Remove the following items and wash with hot soapy water.
Load Tray - Figure 2
Exit End Tray - Figure 2
2. Wipe conveyors with damp cloth as they cool.
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3. Remove grease residue from any part of remaining broiler structure where visible. Use a damp cloth with detergent
and a putty knife for best results.
4. After cleaning all removable parts as noted, allow to dry and reassemble.
QUARTERLY CLEANING PROCEDURES
1. Remove lower burners from both broiler tunnels if examination reveals debris on the burner face.
2. Open conveyors and lay chain aside. Refer to Figure 3 for proper conveyor reassembly.
3. Remove upper burners and screens.
4. By reaching in through openings in upper broiler section, scrape any residue from tops of burner shields.
5. Remove ash and debris from lower broiler section and vacuum inside of broiler tunnel.
6. Reinstall burner screens, burners and conveyor (see Figure 3).
7. Clean gas orifices:
• Orifices are passageways directing gas flow into burner. Uneven gas flow or air to
gas ratio is caused by dirty or damaged orifices.
• Orifices are made of brass. Use special care in cleaning—don't gouge or make
gas holes bigger.
• To reach orifices, remove burners.
• Use a pipe cleaner dipped in rubbing alcohol to clean orifices. Swab until clean;
free of carbon build-up. Do not use drill bit; this damages orifice.
EVERY TWELVE MONTHS
1. Lubricate roller chain very lightly with SAE 30 oil.
2. Remove all motor brushes and replace if less than 1/4" is left (see Figure 4).
3. INVENTORY THE SPARE PARTS KIT AND ORDER MISSING PARTS AS NEEDED. KEEP A COMPLETE
SET OF PARTS ON HAND AT ALL TIMES.
V. PREVENTIVE MAINTENANCE
1. In addition to daily cleaning, there is little preventive maintenance necessary on the Autobroil™.
Bearings are high temperature, long-life bearings that need no lubrication. They are shown in Figure 4. After several
years of continuous use, it may be necessary to replace the bearings. They should be replaced with bearings
obtained from the Factory only, since they are special high temperature type bearings.
2. The drive motors shown in Figure 4 are a DC type motor that employs motor brushes. These brushes should be
checked for wear on a yearly basis. Replace the brushes when they have worn in length to 1/4" or less.
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3. Inspect the roller chain in Figure 2 for slack. There should be at least 1/2" slack on a cold machine or
chain will be too tight when the machine heats. Remove any excessive slack by loosening the screws
holding the motor in place and sliding the motor to one side to tighten the chain. If no adjustment
remains, then shorten the roller chain. Lubricate the roller chains with a few drops of oil as needed.
4. Inspect conveyor for excessive slack. Figure 2 shows the automatic adjustment spring. After all of the
adjustment has been used, remove a conveyor link (see Figure 3).
VI. TROUBLESHOOTING
This section contains a list of imagined problems with your Autobroil™ oven. By locating the problem in this section, you
may be able to make a quick repair. ALL ELECTRICAL TROUBLE SHOOTING INVOLVING ACCESS INTO THE
MOTORS OR ELECTRICAL ENCLOSURES MUST BE PERFORMED BY A QUALIFIED ELECTRICIAN. ALL ITEMS
MARKED WITH ASTERISKS SHOULD BE PERFORMED BY SERVICE AGENCY QUALIFIED TO PERFORM
SERVICE ON GAS FIRED APPLIANCES.
1. BURNER BACKFIRES
Flashback, blue flame at entrance to burner makes motor-boating sound like a blow torch. IMPORTANT: if
burner backfires, turn it off. Continued operation will cause damage to the entire burner.
POSSIBLE CAUSE:
* A) Burner overtired - manifold pressure too high. Check high and low pressure at the gauge to give
pressure values shown on Page 7. Wait 5 minutes and relight. Flashback will not occur immediately
unless a large opening in or around the burner grid is evident. Wait an hour after relighting to check if
problem is solved.
B) Burner grid or burner gasket failure. Replace burner grid or gasket (Figure 9).
2. FLAMES VISIBLE AT UPPER BROILER SECTION FLUE
POSSIBLE CAUSE:
* A) Low gas pressure. Check that gas pressure is not less than 3.0 IWC on natural and 6.0 IWC on
propane.
3. PILOT FLAME GOES OUT
POSSIBLE CAUSE:
* A) Increase size of pilot by adjusting gas quantity. This is accomplished by turning the screw in the top
of valve (see Figure 11).
* B) Remove pilot orifice and clean.
4. PILOT DOES NOT LIGHT
POSSIBLE CAUSE:
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* A) Pilot flame too small. Adjust gas control valve to give a larger pilot flame (see Figure 11).
* B) Low gas pressure. Increase gas pressure to appliance.
* C) Pilot orifice clogged. Dislodge debris or replace orifice.
5. BURNER WILL NOT LIGHT AT ALL
POSSIBLE CAUSE:
* A) Orifice. Check that orifice is not plugged. (If it is necessary to change the orifices, new ones must be
B) Check that flame runner is properly mounted and no parts are clogged.
* C) Check that flame runs up arm and turns into upper broiler section.
D) Pilot. Pilot must light and stay lit in order for burner to light. Check pilot problem list.
6. CONVEYOR CHAIN WILL NOT MOVE
POSSIBLE CAUSE:
A) UNPLUG UNIT FROM ELECTRICAL OUTLET.
* B) Check 1 amp fuse on the speed control circuit board.
* C) Check 5 amp fuse (inside control cabinet).
* D) Check on/off switch to make sure power is flowing through the switch.
E) Check for object caught in conveyor, causing a jam.
F) Check to see if motor shaft is moving. If so, then sprocket needs to be tightened on motor or conveyor
ordered from the factory.)
shaft.
G) Check pick-up on end of motor shaft to see if it is in place and if wires are intact (see Figure 4).
H) Locate plug in motor cord and disconnect motor electrically. Remove pick-up by snapping black cap
7. NO SPEED CONTROL ON CONVEYORS
POSSIBLE CAUSE:
A) If conveyor runs full speed (30 second cook time) all the time, change the pick-up as described
off of end of blue pick-up and remove screw. To loosen screw it is necessary to grip motor shaft on
rear of motor with a 1/4" wrench so the shaft does not turn when applying pressure to screw. Attach
pick-up to new motor and with new motor plugged to cord (but not mounted) see if motor runs. If so,
then install new motor. If not, then change circuit board.
in Item 6H.
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* B) Connect the wires from the board of the conveyor with no control onto a spare circuit board. If
* C) If connecting the wires into the spare board does make it work, then the circuit board has failed.
8. REPEATED MECHANICAL BINDING
POSSIBLE CAUSE:
A) Check for excessive conveyor slack. See Page 10, Item 4 under Preventive Maintenance.
B) Check to see that chain is not on backwards. See proper chain installation on Figure 3.
there is still no control, the speed selector for that conveyor has failed.
C) Inspect chain closely for bent or warped links that may be hanging up and causing a
D) Visually inspect the motor drive chain assembly for smooth rotation of chain and make
E) Make sure the axle assembly is clean and free of grease and food residue to allow smooth
F) Check the axle assembly to make certain all set collars, bearings, etc. are properly
G) Disassemble conveyor axle assembly and check condition of green bearings for excessive wear.
9. FOOD IS COOKED INCONSISTENTLY
A) Check for correct conveyor speed and temperature.
B) Check for gas pressure at gauge. It should average around 3" pressure under no load.
C) Make sure both top and bottom burners are glowing dull red at low temperature settings and bright
D) Check that high and low gas pressures are as shown on Page 7 when temperature controller is
E) Check that food is being held at consistent temperature. (Food will be inconsistent if some is partially
binding condition. Also check that the chain links are not climbing out of the sprockets as the
conveyor rotates.
certain there is no binding or worn components. Check for proper slack per Item 3 bottom of Page
10.
movement of the conveyor.
positioned and secure.
orange at high temperature settings.
set at High and Low settings.
frozen and some is properly thawed.)
** INSTRUCTIONS MARKED WITH ASTERISKS SHOULD BE PERFORMED BY A QUALIFIED SERVICE
COMPANY.
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