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SERVICE MANUAL 
 
DUAL TECHNOLOGY FINISHER 
 
MODEL 1920 SERIES 
 
 
 
 
 
Lincoln Foodservice Products, LLC 
1111 North Hadley Road 
Fort Wayne, Indiana  46804 
United States of America 
 
Phone : (800) 374-3004 
U.S. Fax: (888) 790-8193   •   Int’l Fax: (260) 436-0735 
 
Technical Service Hot Line 
(800) 678-9511 
 
www.lincolnfp.com 
 
 
 
 
 
 
 
 
 
DTFsvcman  REV 1/5/07                                                                                                                    
                    
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                        SEQUENCE OF OPERATION  DUAL TECHNOLOGY FINISHER    1921  208VAC 60 HZ.  3 PHASE  1922  240VAC 60 HZ.  3 PHASE      POWER SUPPLY Electrical power to be supplied to the oven by a four conductor service for three phase.  Black conductor is hot.  Red conductor is hot.  Orange conductor is hot   Green conductor is ground.  MAIN FAN CIRCUIT Power is permanently supplied through the 10 amp fuses, through the normally closed  oven cavity hi-limit thermostat, to the normally open main power switch and to
                    
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                        SCHEMATIC DIAGRAM  MODEL 1921 S/N 8001207 and Below    DTF – 1920 Series Service Manual 3                                                                                                                                                                                                                                                                                                                                                                                                                           
                    
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                        SCHEMATIC DIAGRAM  MODEL 1922 S/N 8001207 and Below      4 DTF – 1920 Series Service Manual                                                                                                                                                                                                                                                                                                                                                                                                                         
                    
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                        SCHEMATIC DIAGRAM  MODEL 1921 / 1922 S/N 8001208 and Above                    DTF – 1920 Series Service Manual 5                                                                                                                                                                                                                                                                                                                                                                                                    
                    
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                        TROUBLESHOOTING GUIDE         1921   208 VAC  60 HZ. 3 PHASE     1922   240 VAC  60 HZ. 3 PHASE    SYMPTOM POSSIBLE CAUSE EVALUATION  Oven fan will not run Incoming power supply Check circuit breakers. Reset if required. Call power  co. if needed.   Fuses, 10 Amp, motor and Check, replace if necessary.  controls   Fuse holder Check, replace if necessary.     Hi-limit thermostat,  Terminals are normally closed. If open, reset  Oven cavity        thermostat and retest. If thermostat will not hold 
                    
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                         Control transformer Check for 208/240VAC supply to the primary of the  control transformer. If no voltage is present, trace  wiring back to the main power switch. If voltage is  present, check for 24VAC at the transformer  secondary. If there is primary voltage, but no secondary  voltage, replace the control transformer.   Oven control Check for 24VAC supply to control. If no voltage is  present, trace wiring back to control transformer. If  24VAC is present, check for a read-out on the display
                    
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                        a digital multimeter.  The element resistance  should be as follows:  208V – 43 ohms    approx.   240V – 57 ohms    approx.  Replace heating elements as needed.  No Infrared Heating Main fan motor Check for main fan operation. If it is not operating, refer  to “Oven fan will not run”.   Air pressure switch Check for 208/240VAC to the air pressure switch. If no  voltage is present, trace wiring back to main power  switch. This normally open switch should close when  the main fan is activated. Ref
                    
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                         Switch, Main Power WITH POWER OFF: Check continuity between switch  terminals. Replace switch as needed.   Control transformer Check for supply voltage to the primary of the control  transformer. If no voltage is present, trace wiring back  to the oven power relay. If voltage is present, check for  24 VAC at the transformer secondary. If there is  primary voltage but no secondary voltage, replace  control transformer.   Air pressure switch Check for 208/240VAC to the air pressure switch. If no 
                    
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                        REMOVAL, INSTALLATION AND ADJUSTMENT    DUAL TECHNOLOGY FINISHER    CAUTION!  BEFORE REMOVING OR INSTALLING ANY COMPONENT IN THE DUAL TECHNOLOGY  FINISHER, BE SURE TO DISCONNECT THE ELECTRICAL POWER SUPPLY.      MOTOR, MAIN FAN - REPLACEMENT    1. Shut off power at main breaker.  2. Remove conveyor and finger assemblies from oven (see installation operations  manual).  3. Remove front plenum assembly. Measure location of main fan on motor shaft for  reassembly. Loosen two set screws and remove m
                    
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                        CIRCUIT BREAKER, MAIN MOTOR - REPLACEMENT    1. Shut off power at main breaker.  2. Remove rear cover.  3. Remove wires from appropriate circuit breaker and mark wires for reassembly.  4. Remove mounting nut from circuit breaker and remove circuit breaker.  5. Reassemble in reverse order and check system operation. Be sure to reset circuit  breaker before operation.    FUSE HOLDER - REPLACEMENT    1. Shut off power at main breaker.  2. Remove rear cover.  3. Remove wires from appropriate fuse ho
                    
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                        CAPACITOR, CONVEYOR MOTOR – REPLACEMENT    1. Shut off power at main breaker.  2. Remove control box top. Remove tube from air pressure switch.  3. Remove wiring from air pressure switch and conveyor motor capacitor and mark all  wires for reassembly.  4. Remove two screws and remove air pressure switch/capacitor mounting bracket.  5. Remove capacitor from mounting bracket.  6. Reassemble in reverse order and check system operation.    CONVEYOR MOTOR – REPLACEMENT    1. Shut off power at main br
                    
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                        THERMOCOUPLE MEASUREMENT    TEMPERATURE (°F) D.C. MILLIVOLTS   200°   2.8   250°   4.0   300°   5.1   350°   6.0   400°   7.1   450°   8.2   500°   9.3   550°   10.4   600°   11.5       THERMOSTAT, HI-LIMIT – REPLACEMENT    1. Shut off power at main breaker.  2. Remove rear cover, remove right side heating element cover.  3. Remove hi-limit thermostat from the mounting bracket. Remove mounting nut from hi- limit thermostat. Remove hi-limit thermostat.  4. Form 90° bend in hi-limit thermostat.  5
                    
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                        voltage (120/240) and frequency (50Hz./60Hz.). After the new control is installed, the  control will need to be initialized. To initialize the new control, press and hold the two center  buttons on the front control panel. After the oven starts, release the buttons, the control is  now initialized. Reassemble in reverse order and check system operation.                                                                                         14 DTF – 1920 Series Service Manual                     
                    
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                        GENERAL VIEW  MODEL 1921, 1922      A 370438 Finger housing, lower  B 370441 Columnating plate, lower  C 370443 Finger cover, lower left. Marked ‘LS’  D 370444 Finger cover, lower right. Marked ’RS’  E 370445 Front element cover  F 370446 Front cover  G 370447 Finger cover, upper  H 370442 Columnating plate, upper  I 370439 Finger housing, upper  J 370448 Air wash panel, upper  K 370449 Air wash panel, lower  L 370450 ¼ turn fastener  M 370451 Air return assy.  N 370452 Finger support, upper  O 
                    
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                        CONTROL BOX VIEW  MODEL 1921, 1922      A 369432 Switch, on/off  B 370456 Label, control panel  C 370457 Front panel  D 369460 Spring, compression  E 369413 Drive key  F 369410 Coupling sleeve  G 370106 Washer  H 350259 Screw  I 370458 Heating element, Infrared – 208VAC   370460 Heating element, Infrared – 240VAC  J 370462 Motor, conveyor  K 370383 Capacitor, conveyor motor  L 369430 Air pressure switch  M 370463 Top, control box  N 370464 Control, main and display  O 370465 Cover, rear control 
                    
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                        REAR VIEW  MODEL 1921, 1922      A 370466 Timer, cool down, 30 minute  B 369422 Relay, main fan  C 370467 Thermocouple  D 370468 Cover, heating element  E 370469 Motor mount   F 370470 Motor, main fan S/N 8001207 and Below   4060485 Motor, main fan S/N 8001208 and Above  G 370468 Cover, heating element  H 370471 Cooling fan  I 370472 Air switch tube assy.  J 369427 Transformer, control  K 370459 Heating element, 208VAC   370461 Heating element, 240VAC  L 369479 Relay, Heating element  M 369409 M