Blodgett MT2136 Series, Service And Repair Manual

Page: 31 / 94

MT2136
3-7
MT2136E GENERAL EXPORT WITH ATHENA CONTROLS - M2341 REV F
COMPONENT REFERENCE
NOTE: Refer to FIGURE 5 page 3-26 for compoĆ
nent locations.
1. BLOWER SWITCH (M0153)
2. HI/LO BOARD (M3150)
3. TEMPERATURE CONTROLLER (M3149)
4. MOTOR CONTACTOR (M2247)
5. CONVECTION FANS (Clockwise - M2873,
CounterĆclockwise - M2872)
6. THERMOCOUPLES (Dual lead - M3151,
Single - M3152)
7. HEAT SWITCH (M0152)
8. SPST THERMAL SWITCH (M1362, L140Ć20F
or M2734, L165-30F)
9. SPST THERMAL SWITCH (M1362, L140Ć20F
or M2734, L165-30F)
10. ELEMENT CONTACTOR (R1530)
11. HEATING ELEMENTS (220/380VAC, 3
F -
M2573 or 240/315 VAC 3 F - M2574)
12. SPST THERMAL SWITCH (M0635, F110Ć20F)
13. COOLING FANS (23034)
14. SPST THERMAL SWITCH (M0635, F110Ć20F)
15. CONVEYOR SWITCH (M0152)
16. TIME DISPLAY (M3154)
17. 10k
W POTENTIOMETER (M3145)
18. D.C. SPEED CONTROL BOARD (M3153)
19. 180 VDC MOTOR (M3128)
20. #10 HALL EFFECT PICKUP (M3147)
OPERATION
1. Turn the blower switch (1) to ON. The N.O. conĆ
tacts close, the N.C. contacts open. 115 VAC
runs to terminal #7 of the hi/lo board (2), L1 of
the temperature controller (3) and the coil of
the motor contactor (4). Terminal #7 is an outĆ
put. It remains powered after the oven is shut
down to keep the convection fans (5) operatĆ
ing until the unit reaches 135Ć170 F (57Ć77 C)
as sensed by the thermocouples (6).
NOTE: Two thermocouples are located beĆ
tween the convection fans in the rear of
the oven. One thermocouple provides
DC millivolts to the Hi/Lo limit board.
The other provides DC milivolts to the
temperature controller. Check thermoĆ
couples with a millivolt meter.
2. Turn the heat switch (7) to ON. 115 VAC is supĆ
plied to terminal #5 of the hi/lo board (2). If the
temperature is below 600 F (316 C) a switch
is made between terminals #5 and #6 allowĆ
ing power to go to the common terminal of the
temperature controller (3). If the temperature
controller (3) is calling for heat, a switch is
made between common and N.O. Power is
sent to one side of a N.C. SPST thermal switch
(8). The switch toggles if the temperature
passing its face exceeds the rating on the back
of the switch.
NOTE: The switch is located in the slide out
control compartment. It protects the othĆ
er components from hi ambient heat.
If this switch is cold it should be closed, sendĆ
ing power to one side of another N.C. SPST
thermal switch (9). The switch toggles if the
temperature passing its face exceeds the ratĆ
ing on the back of the switch.
NOTE: The switch is located between two conĆ
vection blowers in the rear convection
fan compartment. It protects the other
components from hi ambient heat.
If this switch is cold it should be closed, sendĆ
ing power to the element contactor (10). When
the element contactor closes it sends power to
the heating elements (11).
3. When power is applied to the coils of the motor
contactor (4) the contacts close sending powĆ