NO INTERCOM INPUT POWER.
a. Situation 2. When performing EPC step 1d (set AM-1780 power CKT BKR
switch to ON), a symptom that requires system troubleshooting is shown in
Figure 27. This symptom may be caused by two defects. There could be an
intercom input power problem or the AM-1780 power lamp could be burned out,
which can be verified by performing EPC step 2.
Symptom observed when performing EPC step 1d.