Model MPC-1L, MPC-22, MPC-554
3-3
Oct. 2018
FM06-038-B
Checkout (Continued)
If transformer has 120V at the primary terminals, but more than
14 volts, or less than 10 volts at secondary terminals, replace
transformer.
Replacement:
2. Disconnect the two large, white connectors and remove
component panel from unit.
3. Once component panel is removed, label and disconnect
the wires from the transformer.
4. Using a 5/16” socket or wrench, remove the 2 nuts securing
the transformer and pull transformer from panel. Figure 2.
5. Install new control board in reverse order.
To avoid electrical shock or property damage, move the
power switch to OFF and disconnect main circuit
breaker, or unplug cord at wall receptacle.
1. Slide the component panel out as described in the first step
in Section 2-3.
Checkout:
To avoid electrical shock, make connections before
applying power, take reading, and remove power before
removing meter leads. The following checks are per-
formed with the wall circuit breaker closed and the
main power switch in the ON position.
2. Remove the relay cover from the relay. Figure 1.
Do not use an ohmmeter to check solid state relays. Use a
voltmeter in the procedures below.
3. With no power (5 vdc) going to the relay, 120 volts should
show on the output side of the relay, and 0 volts on the
input (5 volts). If no 120 volts, check heater page 2-6.)
3-4. TRANSFORMER
REPLACEMENT
(Continued)
Figure 2
3-5. RELAY REPLACEMENT
Figure 1
