Service Manual - Market Forge Industries
Contents
1. AT Fa STEAM 501 STEAM SOL G VALVE VALVE V4 MOVED FROMPOWER SWITCH 56 2 5 LENGTH TO BE ADDED ASSEMBLY EXISTING WIRES 120 240v TO 120 240v SUPPLY BOX SUPPLY BOX 9 Li N TO KETTLE oh SOLENOID BOILER CONTROL BOX AUTOMATIC BOILERS 10 FRONT NOTES 1 ALL WIRES 18 AWG AND YELLOW EXCEPT WHERE INDICATED OTHERWISE FRAME GRD 2 FOR WIRE LEAD SCHEDULE REFER TO DRAWING C 91 6472 UI AUGUST 13 2014 10 ST 24M SERIES CONVECTION STEAMERS WIRING DIAGRAMS R 1 REED SWITCH RELAY COIL SOM BUZZER 24 DONE RUN 22 0 ja 5 5 TIMER a gt RELAY 3 RELAY 1 60 MIN TIMER gt COLD WATER a CONDENSER e KETTLE MODE SWITCH lt OPTIONAL ON ST 20 ONLY OYYYYY Oo REED SWITCH RELAY COIL 24 DONE RUN 22 O RELAY TIMER 7 COLD WATER CONDENSER COIL Ad STEAM LIGHT OPTIONAL ON ST 20 ONLY KETTLE SOLENOID VALVE AUGUST 13 2014 11 ST 24M SERIES CONVECTION STEAMERS REPAIR AND REPLACEMENT A CAUTION UNDER NO CIRCUMSTANC2. 17 SIER LOWER TIMER 24 DONE RUN 22 1 EXISTING A WIRES B TO 120 240V 60 MIN TIMER TMR2 120 240V SUPPLY BOX KETTLE LOWER SUPPLY BOX LI SOLENOID N VALVE 120 240v OPTIONAL SUPPLY BOX BOILER CONTROL BOX AUTOMATIC BOILERS L 50 FRONT FRAME GRD STUD AUGUST 13 2014 9 ST 24M SERIES CONVECTION STEAMERS WIRING DIAGRAMS DIGITAL CONTROLS FRONT O FRAME GRD STUD CONNECTOR gt 1 1 83 TIMER 1 COMPARTMENT 9SVAC 265vAC REED SWITCH si Rise f RELAY RI COLD WATER COLD WATER CONDENSER CONDENSER vi v2 MOVED FROM 181 6 i 2 i TERMINAL L TM eh g MODE SWITCH N THERMOSTAT THERMOSTAT el f L D E SWITCH SWITCH 6060 6 53 54
3. Steam fails to enter cooking compart a Faulty steam solenoid valve Replace valve See Steam Solenoid ment with indicator light on Valves b Faulty wiring Inspect condition of wire and tight ness of all connections Correct as needed 3 Steam enters compartment continu a Constant steam position Move knob to timing location ously Timer dial not turning b Faulty thermostatic switch Replace switch See Cooking Com partment Thermostatic Switch c Faulty timer motor Replace timer See 60 Minute Tim er d Faulty steam solenoid valve Replace valve See Steam Solenoid Valves e Faulty wiring Inspect condition of wire and tight ness of all connections Correct as needed 4 Steam continues to flow into Timer contacts faulty Replace timer See 60 minute timer ment and or buzzer fails to sound at Buzzer faulty Replace buzzer See Buzzer end of timer setting Faulty wiring Inspect condition of wire and tight ness of all connections Correct as needed 5 Steam flows continuously from boiler a Cold water not connected Turn on external shut off valve or direct connected steam control p Faulty thermostat Replace thermostat See Cooking drain line with cooker in operation Compartment Thermostatic Switch c Faulty cold water solenoid Replace valve d Faulty wiring Inspect condition of wire and tight ness of all connections Correct as needed AUGUST 13 2014 8 ST
4. 6491 9 91 7639 10 91 7318 11 10 9174 12 10 9175 13 91 6940 14 91 6475 15 91 6476 16 91 7334 17 91 7385 18 91 5621 19 91 6492 20 08 4600 21 98 1637 22 91 7684 23 98 1605 24 91 7699 25 10 4586 26 10 8105 27 10 3343 28 10 1956 29 10 2571 30 08 1204 31 10 2184 32 91 7569 33 91 7327 34 98 1632 35 98 1631 36 08 7959 37 08 7960 38 98 1638 39 98 1639 40 98 1640 41 08 2702 42 91 7690 5 MEASURED REED SWITCH ASSEMBLY PLUMBING DRAIN REAR POST COUPLER 1 2 NPT X 5 8 ID BARB ELBOW 900 1 2 IPS BRACKET REAR FRAME SUPPORT CHECK VALVE 3 8 OD BLACK GROMMET SILICONE RED BRACKET CAVITY SUPPORT WELD ASSEMBLY TOP RELAY TUBE RELAY BASE BRACKET RELAY HINGE ASSEMBLY TOP HINGE ASSEMBLY BOTTOM TROUGH DRIP ST 24 ASSEMBLT DOOR ST 24 ASSEMBLY JET PIPE LATCH DOOR SPRING COMPRESSION MECHANICAL CONTROL PANEL WITH SWITCH STRAINER CAVITY WELD ASSEMBLY MIDDLE RACK RACK SIDE NUT 1 2 IPS S S THERMOSTAT SNAP DISC PROBE TYPE NUT BRASS 1 2 IPS SCREW 8 32 3 8 NUT LOCK 8 32 PLUG HOLE WHITE SCREW HEX HEAD 10 32 3 4 LG PANEL SIDE PANEL REAR INSULATION FRONT INSULATION REAR TUBING NORPRENE 3 8 ID TUBING NORPRENE 5 8 ID MECHANICAL CONTROL PANEL WITHOUT SWITCH DIGITAL CONTROL PANEL WITH SWITCH DIGITAL CONTROL PANEL WITHOUT SWITCH BUSHING DOOR WHITE BRACKET REED SWITCH N IN O SIN IN IBIDI IPBPIND IN NIN S
5. IB ININD 5F S5 N N N N NI O AUGUST 13 2014 15 ST 24M SERIES CONVECTION STEAMERS DOOR ASSEMBLY ITEM PART DESCRIPTION QTY 1 91 7386 OUTER DOOR 1 2 91 7387 INNER DOOR 1 3 91 7388 GASKET RETAINING PLATE 1 4 91 7389 DOOR GASKET 1 5 91 5745 DOOR HANDLE 1 6 09 1608 STRIKER 1 7 08 5027 MAGNET 1 8 91 5901 MAGNET BRACKET 1 9 08 4600 COMPRESSION SPRING 2 AUGUST 13 2014 ST 24M SERIES CONVECTION STEAMERS DOOR LATCH AND HANDLE PART NO DESCRIPTION 1 91 5669 LATCH OLD VERSION 2 91 6734 HANDLE OLD VERSION 91 5745 HANDLE NEW VERSION 91 6492 LATCH NEW VERSION AJOJN N N N AUGUST 13 2014 17 ST 24M SERIES CONVECTION STEAMERS CONDENSER ASSEMBLY USE ON 98 1644 ONLY 55 NOTE TOP CAVITY ASSEMBLY SHOWN HERE USE ON 98 1645 ONLY BOTTOM ASSY RESTRICTER MUST BE REMOVED USE ON 98 1644 ONLY TOP 55 USE 98 1645 ONLY 14 BOTTOM ASSY ITEM PART DESCRIPTION QTY 1 10 5859 VALVE STEAM SOLENOID 1 2 08 4892 COUPLER BRASS 3 8 OD X 1 2 THRD NPT 2 3 10 2885 UNION FEMALE 1 2 IPS 1 4 10 2849 NIPPLE CLOSE 1 2 NPT BRASS 2 5 98 1477 COUPLER BRASS BARB 3 8 X 3 8 NPT 1 6 08 6581 TEE MALE 1 2 NPT X FEMAL
6. 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 O Minute position an audible click indicates correct position If zero ohm reading cannot be obtained the timer is defective and must be replaced 7 Remove ohmmeter and replace all five leads on timer terminals Timer Motor A defective timer motor will cause continuous operation in the TIME mode with the timer dial failing to return to the 0 position Since thermostatic switch failure can cause the same symptom fault must first be isolated to the timer by testing the thermostat To confirm timer motor condition proceed as follows 1 Carefully check motor wire leads and tighten loose connections Use care while working with control panel Terminals carry 120 volts 2 Turn on power to the cooker 3 Set timer dial any setting beyond 0 Minute If op eration is correct the motor will turn the dial toward O 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 lights from turning on and steam solenoid from opening when the timer dial is set If steam does not enter the compartment and the
7. 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 off power to the cooker 2 Disconnect wires to the door switch terminals 3 Connect an ohmmeter between the terminals of the switch 4 Actuate the switch by closing the cooking compart ment door If a zero reading cannot be obtained the switch is defective and must be replaced 5 Remove the ohmmeter and replace the leads on switch terminals STEAM SOLENOID VALVES When either inlet solenoid valve fails to operate the fault may be a defective coil A defective coil is found using an AC volt meter to check the voltage at the coil wire ter minals with the cooker compartment operating in either CONSTANT STEAM or 60 MINUTE TIMER mode If volt age of 120 volts is present and the coil fails to open the valves the fault is in the valve coil Defective valve coils are not separately replaceable requiring complete valve replacement AUGUST 13 2014 ST 24M SERIES CONVECTION STEAMERS TROUBLESHOOTING 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 verified by using an AC volt meter at the leads with input power on the selector switch in the correct position for that timer the timer set and the
8. is converted to water by the cold water condensing systems for each compartment STEAM EXHAUST CONDENSING SYSTEM The steam condensing system consists of the identical two position normally closed cold water solenoid valves with outlet sides connected into the exhaust plumbing for each cooking compartment A spray nozzle directs cold water about the inside of the drain lines to increase cold water contact with exhausted steam Valve inlet sides are connected remote from the supply line of the steam boiler or direct connected steam plumbing The valves respond to a thermostatic switch located inside the com partment When the timer starts the cold water solenoids will energize ELECTRICAL CIRCUITS The electrical circuits of the cooker control the power to activate timer motors and energize solenoid operated valves and circuits which in turn control application of steam to the cooking compartment and condensation of steam from the exhaust line The cooker operates on 120V 2 amp 6OHz electrical service connected to all cir cuits from the circuits of the steam boiler or direct con nected steam controls contained within the cabinet on which the cooker is mounted Power is supplied to the control circuit at all times when the shut off device Circuit Breaker for the unit installed by a certified Electrician is in the ON position Control Circuit Components A brief description of the electrical circuit elements fol lows 6
9. 0 Minute Timer Constant Steam The timer contains a 120 volt AC synchronous motor that drives a timing dial through a gear reduction and clutch mechanism The timer dial is manually set for any interval of operation from 0 to 60 minutes or constant steam as read on the calibrated dial face The manual rotation of the dial moves the common element 1 of the timer switch from the neutral OFF position to contact 3 which con nects with the steam inlet solenoid valve operating circuit The cooker is placed into automatic operation with the setting of the timer dial Its timing cycle however is auto matically delayed by a thermostatic switch which assures operating temperature is achieved before the timer motor begins to time out When the timer motor has operated for the preset duration the common element is trans ferred to contact 4 returning the inlet solenoid valve to the closed position and energizing the buzzer Contact to the buzzer circuit remains closed until the dial is manu ally turned to the OFF position returning the common ele ment 1 of the timer switch to the neutral position Indicator Lights An indicator light is included for both compartments The light remains on red at all times when the coinciding tim er dial is set and the door interlock switch is closed The light turns off at the end of the timed cooking duration or when the set time has elapsed Buzzer The buzzer is an alarm device that o
10. 0 Minute timer contacts b Buzzer c Wiring a b Wiring AUGUST 13 2014 ST 24M SERIES CONVECTION STEAMERS TROUBLESHOOTING ELECTRICAL INSPECTION The first step in any electrical trouble shooting procedure is a thorough physical inspection of all wiring connections To access electrical components remove the control pan el as explained in Exterior Panel Removal Before removing control panel checking connections and wiring be sure that the cir cuit breaker for incoming power is OFF When power is supplied all exposed terminals of the control panel carry 120 volts Check all wiring connections by hand to assure that both ends of all connection points are tightly secured Use a screwdriver to tighten connection points If necessary vi sually inspect all quick disconnect terminals for evidence of corrosion Terminals in this condition should be sepa rated cleaned with emery cloth until shiny and tightly re connected 60 MINUTE TIMER Timer Contacts Defective timer contacts will result in failure of either cook er compartment to operate When this occurs remove the control panel see Exterior Panel Removal and proceed as follows 1 Turn off power to the cooker at external circuit break er 2 Disconnect all five wires from timer terminals 3 Connect an ohmmeter between terminals 1 and 3 4 Rotate timer dial beyond the O Minute point any setting to obtain
11. 24M SERIES CONVECTION STEAMERS WIRING DIAGRAMS MECHANICAL CONTROLS 182 NOTES 1 ALL WIRES 18 AWG AND YELLOW EXCEPT WHERE INDICATED OTHERWISE RELAY R3 RELAY R4 2 FOR WIRE LEAD SCHEDULE REFER DRAWING 91 6472 FRONT O 82 FRAME GRD 3 KETTLE SWITCH IS AN OPTIONAL FEATURE STUD WHT PILOT LIGHT UPPER LTI GRN N VA COLD WATER 1 CONDENSER RELAY RI VI 14 13 COLD WATER CONDENSER 43 V2 Ki BLK REED SWITCH 52 UPPER 27 438 5 37 THERMOSTAT THERMOSTAT SWITCH SWITCH 53 54 WHT 41 gt 46 S 60 MIN TIMER 35 mig TMRI UPPER STEAM STEAM SOL SOL MODE SWITCH VALVE VALVE 171 MOVE FROM TB2 8 22 V3 v4 MOVE FROM TB2 7 i 4 S 172 Bl x 16 LT2 GRN 235 i Way OPTIONAL WAH 51 20 ONLY G 24 WHT LOWER 171 172 A 3 6
12. E 1 2 BRANCH 1 7 10 3739 1 2 X 3 8 REDUCING BUSHING 1 8 98 1630 WELDMENT COLD H20 STEAM VALVE 1 9 10 1055 TEE 3 8 ALL ROUND 1 10 10 3644 PLUG SQUARE HEAD 3 8 IPS BRASS 1 11 08 7525 MIPPLE CLOSED 3 8 NPT BRASS 2 12 08 6498 VALVE 3 8 NPT COLD WATER CONDENSER 1 13 08 4912 COUPLER BARB 5 8 OD X 1 2 IPS 1 14 08 7962 COUPLER BARB 5 8 OD X 3 8 IPS 1 15 98 1477 COUPLER BRASS BARB 3 8 X 3 8 THD NPT 1 AUGUST 13 2014 18 ST 24M SERIES CONVECTION STEAMERS
13. ES SHOULD HARDWARE OR PARTS BE REPLACED WITH A DIFFERENT LENGTH SIZE OR TYPE OTHER THAN AS SPECIFIED IN THE PARTS LIST THE HARDWARE USED IN THE COOKER HAS BEEN SELECTED OR DESIGNED SPE CIFICALLY FOR ITS APPLICATION AND THE USE OF OTHER HARDWARE MAY DAMAGE THE EQUIPMENT AND WILL VOID ANY WAR RANTY Door Latch Tension Adjustment A CAUTION SHUT OFF MAIN ELECTRICAL POWER TO UNIT Procedure 1 Open the cooking compartment door 2 Remove the control panel by removing the eight mounting screws and disconnecting the wire plug and restraining wire 3 Tighten both nuts down until the springs are fully compressed 4 Back each nut off 1 2 turn 5 Remount the control panel reconnecting wire plug and restraining wire Door Handle Tension Adjustment Procedure 1 Open the cooking compartment door 2 Remove the six screws and washers from the top edge and bottom edge of the door 3 Remove the inner door gasket mounting plate assem bly from the outer door Do not disassemble these three components remove them as an assembly 4 Tighten both nuts down until the springs on the outer door are fully compressed 5 Back each nut off 1 2 turn 6 Remount the inner door gasket mounting plate as sembly by assembling the six screws and washers Door Gasket Replacement The cooking compartment door gaskets are made of a silicone type rubber material that is very durable but sub ject to wear during normal operat
14. Switch will allow the user to set the mode of the steam The user can either set the switch so that top and bottom cavity are in use at the same time Or the bottom cavity and a separate direct connected kettle can be used at the same time AUGUST 13 2014 ST 24M SERIES CONVECTION STEAMERS TROUBLESHOOTING TROUBLE SHOOTING GUIDE A trouble shooting guide for use by service personnel is given in the table below ELECTRICAL FAULT ISOLATION Correction of an electrical failure first requires isolation of the fault to a single circuit or component In most cases the nature of the failure and its effect upon the operation of the cooker will be sufficient to narrow it down to one or more circuit elements The Electrical Fault Isolation table is provided as a guide for isolating electrical faults ELECTRICAL TROUBLE SHOOTING PROCEDURES Before performing the trouble shooting procedures in this section the serviceman must be familiar with the function of all controls as described in the Operation section as well as with the Principles of Operation ELECTRICAL FAULT ISOLATION GUIDE The electrical trouble shooting procedures that follow re quire access to components and terminals of the electri cal control panel Electrical controls are reached by re moving screws that fasten the control panel to the frame The panel may be pulled forward for testing while inter connected to the cooker circuits or disconnected at the pin connecti
15. W MARKET FORGE I N D U S ST 24M SERIES 12 PAN PRESSURELESS STEAM COOKERS PARTS AND SERVICE MANUAL EFFECTIVE AUGUST 13 2014 Superseding All Previous Parts Lists The Company reserves the right to make substitution in the event that items specified are not available ERRORS Descriptive and or typographic errors are subject to correction MARKET FORGE INDUSTRIES 44 Lakeside Avenue Burlington Vermont 05401 USA Telephone 802 658 6600 Fax 802 860 3732 www mfii com P N 14 0290 Rev A 8 14 TABLE OF CONTENTS PRIN IPEESSOF OPERATION ss os eS Oe 3 TROUBLESHOGWNG eee Ba i Da 5 WIRING DIAGRAMS K NEN N ee eee NEE E KEKE EEK Med oe aoe 9 REPAIR AND REPLACEMENT uussa ssa saa K a 12 ILLUSTRATED PART LIST CONTROL PANEL ASSEMBLY 22 Nae 13 lt 55 ied adage ekki i eas 14 DOOR ASSEMBLY E E e 16 DOOR CATCHAND HANDLE BSE si ea a 17 GONDENSERASSEMBLX din E E aaa 18 AUGUST 13 2014 2 ST 24M SERIES CONVECTION STEAMERS PRINCIPLES OF OPERATION GENERAL The ST 24 Pressureless Steam Cooker consists of two identical cooking compartments one above the other in a single cabinet as
16. ciding timer dial set at the O Minute position If volt age is 120 volts the fault is in the buzzer which must be replaced If 120 volts is not present the fault is in the wir ing or control components timer or selector switch COLD WATER CONDENSER CIRCUIT If during cooker operation steam exits from the drain line opening located in lower boiler compartment the condensing system fails to operate as evidenced by repeated discharge of water from the drain line the condensing circuit is malfunctioning The failure can be caused by a defective condenser thermostat or cold wa ter solenoid coil or by wiring failure To test condenser thermostat refer to Cooking Compartment Thermostatic Switch If the condenser thermostat functions correctly but ei ther of the cold water solenoid valves fails to operate the cause might be a faulty valve coil A defective coil is found using an AC volt meter to check the voltage at the coil wire terminals with the cooker compartment in operation If voltage of 120 volts is present and the valve fails to open the fault is in the valve coil Defective valve coils are separately replaceable WIRING All of the electrical components of the cooker timers in dicator lights etc are connected to each other by wiring If all of the electrical components are operating correct ly and the incoming power has been checked but the cooker fails to operate the fault lies in the wiring The W
17. 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 or control components selector switch timer or door switch COOKING COMPARTMENT THERMOSTATIC SWITCH A thermostatic switch included in the circuit for the timer motor delays timer operation until steam flowing into the compartment satisfies the temperature actuated switch device If a timer motor fails to operate within about one minute after the indicator light comes on with cooker compartment empty the cause may be a defective ther mostatic switch To test the switch proceed as follows 1 Disconnect the two wires connected to the thermo static switch terminals 2 Connect an ohmmeter between the two terminals of the switch 3 Place the cooker into operation and observe ohmme ter dial Within one minute of operation the switch contacts close automatically to register a zero ohm reading on the dial If a zero ohm reading is not ob tained the switch is defective 4 Shut off cooker disconnect ohmmeter leads and re place wires on switch terminals BUZZER If the buzzer does not sound at the termination of the op erator selected timer setting timer dial returned to O Min ute position the fault may be a defective buzzer Buzzer operation is verified using an AC volt meter at buzzer coil connections with input power on and selector switch and coin
18. ion Should the gasket leak readjust the door gasket to the unit or replace it Procedure Replace Gasket 1 Open the cooking compartment door 2 Remove the six screws on the outside of the door and remove the inner door assembly 3 Remove the eight nuts from the door gasket mount ing plate on the inside of the inner door assembly 4 Remove the door gasket mounting plate and the door gasket 5 Install the new door gasket to the mounting plate 6 Reassemble the mounting plate with gasket to the in side of the inner door assembly using the eight nuts 7 Reassemble the inner door assembly using the six screws on the outside of the door NOTE Remember that the lip on the door gasket mount ing plate must fit into the channel on the inside edge of the gasket to insure a proper seal Procedure To Adjust Gasket to Unit To prevent steam leaks around the door adjust the gasket tension to cavity Adjust the gasket by loosening the six screws on top and bottom of door move inner door plate in or out left side or right side and tighten the six screws Exterior Panel Removal To prevent hazard in servicing the cooker certain that the steam supply boiler is shut down the cold water shut off valve is closed and the electrical disconnect circuit breaker for the cooker boiler unit is off before remov ing side panels Access to all internal plumbing and electrical assemblies is from the right
19. iring Diagrams in this manual show all terminals and interconnections within the electrical circuits All num bered terminals are identified and all leads number coded as shown Connections can be easily removed The Schematics show the same information schemati cally and is an aid in isolating circuits for testing Using an ohmmeter wiring continuity between the connections shown on the wiring diagram is readily verified 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 AUGUST 13 2014 ST 24M SERIES CONVECTION STEAMERS GENERAL TROUBLESHOOTING GUIDE TROUBLESHOOTING PROBLEM PROBABLE CAUSE S REMEDV 1 Indicator light fails to light with timer a Power to cooker off Locate external circuit breaker for set incoming power and place in ON position b Door interlock switch contacts Shut cooker door to close switch not closed contacts Check alignment of door with switch Door interlock switch faulty Replace switch See Door Interlock Switch Indicator light burned out Replace light Faulty timer contacts Replace timer See 60 Minute Tim er f Faulty wiring Inspect condition of wire and tight ness of all connections Correct as needed 2
20. on for complete removal and repair INCOMING POWER Before trouble shooting any of the electrical parts or as semblies verify that power is being supplied to the cook er Incoming power is connected at the boiler or direct connected steam control box located in the base cabinet With power connected to the cooker an AC voltmeter is used to measure 120 volts across L1 and L2 If 120 volts is present and the cooker will not operate the fault lies within the electrical circuits of the cooker FAILURE FAULT LOCATION 1 Will not operate in either CONSTANT STEAM or 60 MINUTE TIMER po Incoming power 8 Steam flows continuously from boiler drain line Thermostatic switch Cold water solenoid valve a sitions b Timer c Door interlock switch d Wiring 2 Operating in CONSTANT STEAM position but not in 60 MINUTE TIMER a 60 minute timer position b Wiring 3 Operates in 60 MINUTE TIMER position but not in CONSTANT STEAM Timer position b Wiring 4 Steam solenoid valve fails to open with indicator light on a Solenoid valve coil b Wiring 5 Indicator light off when steam solenoid valve open Indicator light b Wiring 6 With indicator light on and steam solenoid valve open timer dial fails to a Compartment thermostatic switch turn b Constant steam position c Timer motor d Wiring 7 Buzzer fails to sound at end of 60 MINUTE TIMER mode a 6
21. perates by oscillation of a striker against the core of an electromagnet When the 60 minute timer dials reach the O Minute position the buzzer coil is energized to sound the buzzer Move ment of the timer dial to the OFF position opens the con tact to the buzzer coil to shut it off Door Interlock Switch The interlock switch is a single pole proximity switch with normally open contacts The switch is operated by the proximity of a magnet within the door When the door is open the switch contacts remain in the open position When the door is closed and securely latched in place the magnet is near the switch to close the contacts Connected between the operating contact 3 of the tim ers and the steam inlet solenoid valve the door switch acts as a protective device to interrupt valve operation unless the door is closed Thermostatic Switch The thermostatically operated switch is a two position normally open switch mounted on the cooking compart ment The switch functions to activate the cold water sole noid valves of the steam condensing system and to delay timer motor operation until the compartment temperature reaches 195 F thus assuring that cooking temperature exists throughout the timed duration Digital Timers Optional The timer controls the steam to the cavity by either a con stant steam setting or a used defined timer that will be programmed by the user into the timer Kettle Switch Optional The Kettle
22. r compartments are equipped with normally closed solenoid valves operated by the electri cal control circuits The inlet valves are opened whenever the compartment control circuit is activated by use of the 60 minute timers STEAM INLET LINE steam supply line is plumbed from the boiler output or direct connected steam control to a 1 2 inch barb fitting connected to the input sides of both steam inlet solenoid valves When a cooking compartment is not in use the valve for the compartment remains closed to prevent steam from entering During operation the appropriate inlet solenoid valve is opened by activation of the con trol circuit Steam is projected onto the surface of pans of food loaded into the compartment by an orifice located inside the compartment Steam continues to flow through the compartment in this manner until the control circuit closes the solenoid valve WATER INLET TO TOP CAVITY _ STEAM JET PIPE Mi 2 PER COMPARTMENT f WATER DRAIN LINE STEAM LINE TO CAVITY STEAM LINE TO CAVITY _ STEAM LINE FROM BOILER WATER INLET FROM BOILER Figure 1 AUGUST 13 2014 ST 24M SERIES CONVECTION STEAMERS PRINCIPLES OF OPERATION STEAM EXHAUST AND DRAIN LINES Perforated strainers at the drain line openings inside each compartment allow only steam condensation and liquid cooking drainage to enter Prior to discharge into the boil er drain system steam
23. sembly Each compartment is fitted with independent electrically controlled steam circuits and spring loaded self sealing doors with slam action latches Compartments can be used separately or simultaneously for either constant steam or 60 minute timing The prin ciples of operation in this section include an explanation of steam steam condensing and electrical circuits and their functioning PLUMBING CIRCUITS The plumbing circuits consist of the piping steam sole noid valves orifice drain and cold water condenser re quired to provide controlled steam application to the cook ing compartments A simplified diagram of these circuits is shown in below NOTE Figure 1 is strictly a pictorial schematic diagram and is not intended to show the actual configura tion of the plumbing All components are shown in correct relationship with each other However the diagram does not show their actual locations or position within the cooker As shown in the diagram steam inlet and exhaust con nections are connected at the factory directly into a steam boiler or direct connected steam plumbing enclosed within the base cabinet on which the cooker is mounted The boiler or direct connected steam control system is equipped to supply constant regulated steam at 14 15 PSI Steam exhaust having been reduced to water by the cold water condenser is directed into the boiler or direct connected steam control drain system Steam inlet lines fo
24. side and right front The left side panel is removed by removing the bottom screw and pushing up on the panel until the lower lip disengages the frame The electric control panel may also be removed as a unit by removing screws and pulling the panel forward Removal of the control panel is completed by unplugging intercon necting wiring at the pin housing Steam and Water Solenoid Valve Replacement Replacements for the 1 2 inch steam solenoid valves and the 1 4 inch water valves are available as complete units from Market Forge Authorized Service Agencies It is nec essary to replace an entire steam valve when the coil is faulty or the diaphragm ruptures Replacement coils are available for the water valves The valves are accessed as explained in Exterior Panel Removal shown above AUGUST 13 2014 12 ST 24M SERIES CONVECTION STEAMERS CONTROL PANEL ASSEMBLY PART NO DESCRIPTION 1 98 1616 CONTROL PANEL 1 2 98 1612 LEXAN CONTROL PANEL 1 3 08 6464 60 MINUTE TIMER 2 4 08 6541 TERMINAL STRIP 2 5 91 6471 BRACKET TERMINAL STRIP 2 6 10 7395 BUZZER 2 7 08 3826 KNOB TIMER 2 8 10 5052 LIGHT RED 2 AUGUST 13 2014 13 ST 24M SERIES CONVECTION STEAMERS CABINET ASSEMBLY RIGHT SIDE VIEW AUGUST 13 2014 14 ST 24M SERIES CONVECTION STEAMERS CABINET ASSEMBLY ITEM PARTNO DESCRIPTION 1 08 6308 2 08 4912 3 10 2793 4 98 1643 5 08 6538 6 98 1643 7 08 6538 8 91
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