Market Forge ST-5G Service Manual
ST-5G
GAS COUNTERTOP CONVECTION STEAMER
PARTS AND SERVICE MANUAL
EFFECTIVE JUNE 12, 2015
The Company reserves the right to make substitution in the event that items specied are not available.
ERRORS: Descriptive and/or typographic errors are subject to correction.
44 Lakeside Avenue, Burlington, Vermont 05401 USA Telephone: (802) 658-6600 Fax: (802) 860-3732
Superseding All Previous Parts Lists.
MARKET FORGE INDUSTRIES
www.mi.com
P/N 14-0287 Rev C
TABLE OF CONTENTS
GENERAL TROUBLESHOOTING GUIDE ................................................3
TROUBLESHOOTING ..................................................................5
ELECTRICAL FAULT ISOLATION GUIDE ................................................6
WIRING DIAGRAMS ...................................................................7
ILLUSTRATED PARTS LIST
MAIN ASSEMBLY ......................................................................9
DOOR ASSEMBLY ................................................................... 12
BURNER, PROPANE AND NATURAL GAS ASSEMBLY ................................. 13
GAS PLUMBING AND VALVE ASSEMBLY ............................................. 14
JUNE 12, 2015 2 ST-5G
GENERAL TROUBLESHOOTING GUIDE
PROBLEM / PROBABLE CAUSE REMEDY
1. 1. Cooking Indicator Light Fails to Light with Timer Set.
a. Main power circuit breaker tripped. Located external circuit breaker for incoming power and
place in ON position.
b. Door interlock switch contacts not closed. Shut cooker door to close switch contacts. Check alignment
of door with switch.
c. Door interlock switch faulty. Replace switch.
d. Indicator light burned out. Replace light.
e. Faulty timer contacts. Replace timer.
f. Faulty wiring. Inspect condition of wire and tightness of all connections.
Correct as needed.
2. Steam Fails to Enter Cooking Compartment with Cooking Indicator Light On.
a. Faulty wiring.
3. Steam Enters Compartment Continuously. Timer Dial Not Turning.
a. Constant steam position. Move knob to timing location.
b. Faulty thermostatic switch. Replace switch.
c. Faulty timer motor. Replace timer.
d. Faulty wiring. Inspect condition of wire and tightness of all connections.
4. Steam Continues to Flow into Compartment and/or Buzzer Fails to Sound at End of Timer Setting.
a. Faulty timer contacts. Replace timer.
b. Faulty buzzer. Replace buzzer.
c. Faulty wiring. Inspect condition of wire and tightness of all connections.
5. Steam Flows Continuously from Boiler Drain Line with Cooker in Operation.
a. Cold water not connected. Turn on external shut-off valve.
b. Faulty cooling valve. Replace cooling valve.
c. Faulty wiring. Inspect condition of wire and tightness of all connections.
6. Door Leaks.
a. Damaged door gasket. Check gasket for cuts and replace as needed.
b. Clogged compartment drain or plumbing. Remove screen and clean drain line or plumbing.
7. Water Flows into Cooking Compartment.
a. Level probe short circuited. Check and correct.
b. Scale build-up on probe. Clean all probes.
c. Water ll solenoid valve. Plugged, defective, clean or replace.
8. Water Accumulates in Compartment.
a. Plugged compartment drain. Remove screen and clean drain line.
9. Water Flows into Drain During Shut-Down.
a. Cooling valve does not close. Check valve for foreign material or damage.
Inspect condition of wire and tightness of all connections. Correct
as needed.
Correct as needed.
Correct as needed.
Correct as needed.
JUNE 12, 2015 3 ST-5G
GENERAL TROUBLESHOOTING GUIDE
PROBLEM / PROBABLE CAUSE REMEDY
10. Water not Being Supplied to Generator.
a. Water supply off. Check incoming water valve is on.
b. Supply water pressure too low. Call supply agency.
c. Defective water solenoid valve. Replace or clean.
d. Level probe shorted. Check and correct.
e. Defective water level control. Replace.
f. Drain valve is open. Check valve, clean or replace.
IMPORTANT NOTE: These problems are an indication of severe water conditions which should be corrected immediately
to avoid damage to the components and performance of the steamer. Call your Service Agency for Assistance.
ADJUSTMENTS: All units are adjusted at the factory. in case of operation problems at initial installation, check type of gas
supply and manifold pressure and compare it with information on the rating plate.
11. Burners Do Not Come On.
a. Gas supply is off. Locate supply line and turn on.
b. Power switch is off. Located switch in cabinet and turn on.
c. Probe not sensing water level. Clean probes, check wiring.
d. Ignitor not functioning. Check ignition module relay.
e. Combination gas valve not opening. Check that control knob is in the ON position, check that
120 volts is at the gas valve.
12. Burners Produce Carbon Deposits.
a. Incorrect orice size. Check size and correct.
b. Incorrect gas supply. Check size and correct.
c. Incorrect gas pressure. Check gas pressure at manifold. Correct if necessary.
13. Flash Back.
a. Burning inside mixer tube. Reduce primary air.
b. Incomplete combustion. Increase burner input.
c. Sooting of burner. Increase primary air.
d. Miss-located ignitor. Adjust ignitor.
IMPORTANT NOTICE: AT LEAST TWICE A YEAR, HAVE AN AUTHORIZED SERVICE PERSON CLEAN AND ADJUST
THE UNIT FOR MAXIMUM PERFORMANCE.
ADJUSTMENTS AND SERVICE WORK MAY BE PERFORMED ONLY BY A QUALIFIED TECHNICIAN WHO IS EXPERIENCED IN AND KNOWLEDGEABLE WITH THE OPERATION OF COMMERCIAL GAS COOKING EQUIPMENT.
HOWEVER, TO ASSURE YOUR CONFIDENCE, CONTACT YOUR AUTHORIZED SERVICE AGENCY FOR RELIABLE
SERVICE, DEPENDABLE ADVICE OR OTHER ASSISTANCE AND FOR GENUINE FACTORY PARTS.
JUNE 12, 2015 4 ST-5G
TROUBLESHOOTING
FINDING, UNDERSTANDING AND FIXING THE PROBLEM
Timer Contacts (60 Minute Timer)
Defective timer contacts will result in failure of cooker
compartment to operate. When this occurs, remove the
control pan and proceed as follows:
1. Turn off power to the cooker at external circuit breaker.
2. Disconnect all ve wires from timer terminals.
3. Connect an ohmmeter terminals 1 and 3.
4. Rotate timer dial beyond the “0 minute” point (any
setting) to obtain a reading of zero ohms on the
ohmmeter. If zero ohm reading cannot be obtained,
timer contacts are defective and the timer must be
replaced.
5. Move ohmmeter leads to terminals 1 and 4.
6. Rotate timer dial to “0 minute” position (an audible
click indicates correct position). If zero ohm reading
cannot be obtained, timer contacts are defective and
the timer must be replaced.
7. Remove ohmmeter and replace all ve leads on timer
terminals.
Timer Motor (60 Minute Timer)
A defective timer motor will cause continuous operation
in the TIME mode, with the timer dial failing to return to
the “0 minute” position. Carefully check motor condition,
proceed as follows:
1. Carefully check motor wire leads and tighten lose
connections. !! WARNING: !! USE CARE WHILE
WORKING WITH CONTROL PANEL. TERMINALS
CARRY 120 VOLTS.
2. Turn on power to the steamer.’
3. Set timer dial (any setting beyond “0 minute”). If operation s correct, the motor will turn the dial toward “0
minute”. If the motor fails to operate, it is defective
and the entire timer must be replaced.
4. Shut off power to the cooker.
Door Interlock Switch
Malfunction of the cooker door interlock switch prevents
timer indicator light from turning on and steam solenoid
from opening when the timer dial is set. If steam does not
enter the compartment and the cooking indicator light fails
to turn on with the door latch securely engaged, the fault
may be in the door interlock switch. Proceed as follows:
1. Turn off power to the cooker.
2. Disconnect wire to the door switch terminals.
3. Connect an ohmmeter between the terminals of the
switch.
4. Actuate the switch by closing the cooking compartment door. If zero ohm reading cannot be obtained,
timer contacts are defective and the timer must be
replaced.
5. Remove the ohmmeter and replace the leads on
switch terminals.
Indicator Lights
If the cooker compartment functions correctly, with the
single exception that the indicator light fails to light during
operation, the fault is a defective indicator light. A “burned
out” or defective light is veried by using a AC volt-meter
at the leads, with input power on the selector switch in
correct position for that timer, the timer set, and the door
latches closed. If 120 volts is present, the fault is in the
indicator light and requires replacement. If 120 volts is
not present, the fault is in the wiring control components
(selector switch, timer or door switch).
Buzzer
If the buzzer does not sound at the termination of the operator-selected timer setting (timer dial returned to “0 minute” position), the fault may be a defective buzzer. Buzzer
operation os veried using an AC volt-meter at buzzer coil
connections with input power on a selector switch and coinciding timer dial set at the “0 minute” position. If voltage
is 120 volts, the fault is in the buzzer, which must be replaced. If 120 volts is not present, the fault is in the wiring
control components (selector switch or timer).
Wiring
Using an ohmmeter, wiring continuity between the con-
nections shown on the wiring diagram is readily veried.
This is best done in stages, removing only those wires
required for each continuity check. As each lead is replaced, it should be checked for evidence of corrosion and
cleaned if necessary. All leads must be tightly attached so
as to provide a good electrical connection.
JUNE 12, 2015 5 ST-5G
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