Blodgett MT2136 Series, Service And Repair Manual

Page: 43 / 94

MT2136
3-19
MT2136E CE WITH CLOSED LOOP COMPUTER CONTROL - M6476 REV B
COMPONENT REFERENCE
NOTE: Refer to FIGURE 11 page 3-32 for compoĆ
nent locations.
1. COMPUTER (FW525)
2. BELT STOP RELAY (22672)
3. BLOWER RELAY (22672)
4. HEAT RELAY (22672)
5. MOTOR CONTACTOR (M0708)
6. SPDT THERMAL SWITCH (M2453 L140-20F)
7. SPDT THERMAL SWITCH (M2453 L140-20F)
8. COOLING FANS (M2469)
9. CONVECTION FANS (Clockwise - M2873,
CounterĆclockwise - M2872)
10. RTD PROBE (M7427)
11. SPST THERMAL SWITCH (M1362 L140-20F,
M2734 L165-30F)
12. MANUAL RESETABLE HIGH LIMIT SWITCH
(M3295)
13. HEATING ELEMENT CONTACTOR (R1530)
14. HEATING ELEMENTS (M2573)
15. 130 VDC MOTOR (M2378)
16. #2 HALL EFFECT PICKUP (M0984)
17. DC SPEED CONTROL BOARD (M2379)
18. STEP DOWN TRANSFORMER (M7170)
OPERATION
1. Apply power to the oven. Program the time and
temperature into the computer (1). The belt
stop relay (2), blower relay (3) and the heat
relay (4) energize powering up the oven.
2. The blower relay (3) closes sending power to
the motor contactor (5) and the N.C. terminals
of two SPDT thermal switches (6 and 7). The
switches toggle if the temperature passing
their faces exceeds the rating on the back of
the switches and may start the fans even if the
oven is off.
NOTE: One of the thermal switches is located
in the junction box in the convection
fan compartment. The other thermal
switch is located in the cooking comĆ
puter compartment.
Two cooling fans (8) are located in the rear of
the oven. These cooling fans protect the conĆ
vection fans from high ambient heat. Two addiĆ
tional cooling fans (8) are located in the comĆ
puter control compartment. These cooling
fans protect the controls from high ambient
heat.
The motor contactor (5) closes energizing the
two convection fans (9) in the rear of the oven.
3. On a call for heat from the cooking computer
(1), as sensed by an RTD probe (10), the heat
relay (4) closes sending 115 VAC to one termiĆ
nal of a N.C. SPST thermal switch (11). The
switch toggles if the temperature passing its
face exceeds the rating on the back of the
switch.
NOTE: The RTD probe is located in the control
compartment. It should be checked
with an ohm meter. The SPST thermal
switch is located in the rear of the conĆ
vection fan compartment.
If the switch is closed, 115 VAC is delivered to
one terminal of the manual resetable high limit
switch (12). The high limit switch is a bulb and
capillary style switch. It reacts when the oven
cavity temperature exceeds the high limit proĆ
grammed into the cooking computer.
If the manual resetable high limit switch (12)
(12) is closed power is sent to the contact coil
of the heatIng element contactor (13) energizĆ
ing the heating elements (14).