Repair manual

MT1828
2 --- 5
MT1828G DOMESTIC AND GENERAL EXPORT OVENS EXTERNAL MOUNT --- M9776
REV B
COMPONENT REFERENCE
NOTE: Refer to FIGURE 2 for component loca-
tions.
1. BLOWER RELAY
2. BELT STOP RELAY
3. HEAT RELAY
4. MOTOR CONTACTOR
5. SINGLE POLE DOUBLE THROW THERMAL
SWITCH
6. MOTOR CONTROL BOARD
7. SINGLE POLE SINGLE THROW THERMAL
SWITCH
8. RESETABLE HI LIMIT
9. 115/24 VOLT TRANSFORMER
10. FLAME BLOWER
11. IGNITION CONTROL MODULE
12. COOKING COMPUTER
13. PRESSURE SWITCH
14. H.S.I.
15. BU RNER VALVE
16. PROOF OF FLAME ROD
17. SINGLE POLE DOUBLE THROW THERMAL
SWITCH
18. CONVECTION BLOWERS
19. COOLING FANS
OPERATION
1. Apply power to the oven. Program time and
temperature into the computer (12). The blow-
er relay (1), belt stop relay (2) and heat relay (3)
close.
2. When the blower relay (1) closes, 110 V.A.C.
are sent to the coil of the motor contactor (4)
starting the convection blowers (18). When the
motor contactor closes, power is also applied
to the NIC terminal of a single pole double
throw thermal switch (5).
3. When the belt stop relay (2) closes, 110 V.A.C.
are sent to the motor control board (6) and a
single pole single throw thermal switch (7). If
this switch is closed, power goes to the reset-
able hi limit switch (8).
4. If the resetable hi limit switch is closed power
goes to the 115/24 volt transformer (9) located
in the box mounted on the flame blower (10).
The flame blower starts.
5. The secondary side of the transformer (9)
sends 24 volts to one side of the heat relay (3).
If the computer (12) closes the heat relay, the
24 volts will go to t he pressure sw itch (13).
6. If the pressure switch is closed, a circuit will be
completed to the ignition module (11).
7. The ignition module initiates its firing sequence
by starting to spark at the spark electrode (14)
and opening both solenoid valves on the burn-
er valve (15) allowing gas to enter for ignition.
If no flame is sensed by the proof of flame rod
(16) the system shuts down.
NOTE: Some ignition control modules may try
to refire up to 3 times. However, there
will be a longer interpurge period be-
tween each attempt at ignition.
8. The thermal switch (17) toggles from common
to N.O. only when it reaches the temperature
stated on the back of the switch.
9. The convection blowers (18) receive their pow-
er from the motor contactor (4) only.
10. The cooling fans (19) come on only when the
motor contactor (4) is energized or if the ther-
mal switch (17) has toggled.