MPA-200 Stereo PA (320-3003) Troubleshooting Faxback Doc. # 14631
Amplifier
Symptom Cause Remedy
No Output. Faulty AC power cord. Replace
Defective power switch. Replace
Broken wire in the power transformer. Replace
Fuse F1 6A is open. Replace
Main output works Poor contact in phone output jack Repair/Replace
but headphones Defective R134 and R234 Replace
does not work.
No output when a Defective protector circuit IC1 Replace
signal is applied Defective speaker switch SW2 Replace
to the input Defective volume VR101 and VR201 Replace
terminal
VU meter does Poor contact in VU meter Replace
not work. Defective SW3 Replace
Defective D104,D105,D204,and D205 Replace
Sound is Speakers are out of phase (+-). Reconnect and
distrorted with be sure the
little bass phases of the
and unnatural speaker wires
playback are matched
response
A humming sound Either the pin plug, cord, or shield Replace the
interfers while is not connected properly or the cord shield or
playing record. is the cord is improperly plugged in. plug in the
cord.
The ground wire is not connected Connect the
adequately. ground to
the
turntable.
A howling sound Either the record player and speaker Change
occurs when the system are too close together or they location of
volume is in- are unsteady. the record
creased while player and
playing a speaker.
record Place the
turntable
on a sturdy
table or
shelf.
(SP/all-04/20/95)