Repair manual

MT2136
3-21
MT2136G CE WITH COMPUTER CONTROL - M7290 REV E
COMPONENT REFERENCE
NOTE: Refer to FIGURE 12 page 3-33 for compoĆ
nent locations.
1. BLOWER RELAY (22672)
2. MOTOR CONTACTOR (M2247)
3. CONVECTION FANS (CCW) (M2872)
4. CONVECTION FANS (CW) (M2873)
5. CONVECTION PRESSURE SWITCH (M0595)
6. BELT STOP RELAY (22672)
7. DC SPEED CONTROL BOARD (M3153)
8. MANUAL RESET HI LIMIT SWITCH (M3295)
9. HEAT RELAY (22672)
10. SINGLE POLE SINGLE THROW THERMAL
SWITCH (M1362)
11. SINGLE POLE SINGLE THROW RELAY (16775)
12. TRIPLE POLE DOUBLE THROW RELAY (90250)
13. TEN SECOND PURGE TIMER (M3173)
14. DIFFERENTIAL BURNER PRESSURE
SWITCH (M2819)
15. COMBUSTION BLOWER MOTOR (M2386)
16. LANDIS & GYR IGNITION CONTROL SYSTEM
(M3168)
17. 2 SECOND TIMER (M3172)
18. DUAL SOLENOID GAS VALVE
(Natural - M6000, LP - M6001)
19. COOKING COMPUTER (M7880)
20. RTD PROBE (M7427)
21. SINGLE POLE DOUBLE THROW THERMAL
SWITCH (M2453)
22. COOLING FAN (23034)
23. SINGLE POLE DOUBLE THROW THERMAL
SWITCH (M2453)
24. DC Motor (M3128)
25. COOLING FANS (23034)
OPERATION
1. Apply power to the oven. Program the time and
temperature into the computer (19). The blowĆ
er relay (1), belt stop relay (6) and heat relay (9)
pull in and power up three separate circuits.
The voltage to the relay coils is 12 VDC.
2. The blower relay (1) closes sending 230 volts to
the coil of the motor contactor (2). Points 1, 2, 5
and 6 close powering the convection fans (3 &
4).
3. The convection fan pressure switch (5) closes
due to the vacuum that is established in the
burner tube chamber by the operation of the
convection fans.
4. The belt stop relay (6) sends 230 volts to the
DC drive board (7) and the manual reset hi limit
switch (8). The DC motor (24) starts provided
there is a time entered in the cooking computer
(19).
NOTE: The motor used in this oven is 180 volts
DC at its highest speed.
NOTE: This relay will only be powered if there
is a time programmed into the computĆ
er. THE OVEN WILL NOT HEAT IF TIME
IS NOT PROGRAMMED INTO THE
COMPUTER.
5. The heat relay (9) sends 230 volts to a single
pole single throw thermal switch (10). If closed
the relay continues to send power to one side
of a single pole single throw relay (11). This
relay will not see power at it's coil until a triple
pole double throw relay (12) closes and the ten
second timer (13) counts down.
6. Once the convection fan pressure switch (5)
closes, 230 volts go to a differential pressure
switch (14), the combustion blower motor (15),
terminal #7 and the coil of the triple pole
double throw relay (12).
7. When a differential is sensed at the differential
pressure switch (14) the switch changes posiĆ
tion allowing power to go to terminal #9 of the
triple pole double throw relay (12). This relay is
a latching relay and is held closed by power
that was applied at terminal #7.