Model MPC-1L, MPC-22, MPC-554
1-2
Oct. 2018
FM06-038-B
These two test instruments will help to check the electrical
components:
1. A voltmeter
2. An ohmmeter.
When the manual refers to the circuit being closed, the ohmme-
ter should read zero unless otherwise noted. When the manual
refers to the circuit being open, the ohmmeter will read infinite
resistance.
Do not use an ohmmeter to check solid state relays. Use a
voltmeter as decribed in the Troubleshooting Section.
1-3. TEST INSTRUMENTS
1-4. TROUBLESHOOTING
To isolate a malfunction, proceed as follows:
1. Clearly define the problem (or symptom) and when it
occurs.
2. Locate the problem in the troubleshooting table.
3. Review all possible causes. Then, one-at-a-time work
through the list of corrections until the problem is
solved.
PROBLEM
CAUSE
CORRECTION
With power switch in
• Open circuit
• Check to see that unit is
POWER position, unit
plugged in
is completely
inoperative (no power)
• Check breaker or fuse at
supply box
• Check voltage at wall
receptacle
• Check POWER switch;
replace if defective
• Check internal component
connectors, and the cord and plug,
for loose connections
• Transformer defective
• Check input and output voltage;
replace if defective
• Control board defective
• Check for 12 volt input from
transformer; if control board shows
12 volts, replace control board
