This amp appears to have a fully isolated secondary. Find the two speaker terminals that are directly connected (0 ohms between them and use that for the reference point for the following voltage readings.
±rail
±regulated
Voltage on all 3 terminals of the J111 muting transistors. They are likely Q101 and Q201. If they're a different part number, what is it?
±rail
±regulated
Voltage on all 3 terminals of the J111 muting transistors. They are likely Q101 and Q201. If they're a different part number, what is it?
Rail voltage is: ±38.95
As to ±regulated, I'm not sure what/where exactly you are asking me to check the voltage on...?
The components in the Q101 and Q202 location are MBS4993 bidirectional switches.
Q101 DC voltage:
MT1: -1215v
G: -12.88v
MT2: -12.95
Q201:
MT1: -13.06v
G: -13.72v
MT2: -13.84v
As to ±regulated, I'm not sure what/where exactly you are asking me to check the voltage on...?
The components in the Q101 and Q202 location are MBS4993 bidirectional switches.
Q101 DC voltage:
MT1: -1215v
G: -12.88v
MT2: -12.95
Q201:
MT1: -13.06v
G: -13.72v
MT2: -13.84v
Regulated voltage is ±15v (pins 4 and 8) op-amps are BA4560
All the flame proof resistors check good with the exception of the two circled in the attached photo. Both are of the same value but are giving quite different ohm readings. They are also both getting very hot when the amp is powered up.
All the flame proof resistors check good with the exception of the two circled in the attached photo. Both are of the same value but are giving quite different ohm readings. They are also both getting very hot when the amp is powered up.
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As I was going though checking the transistors in the right channel I found one of the 51ohm resistors was shorted open. I replaced it and regained power on that channel. I then checked the resistors in the left channel and found it also had one of the 51ohm resistors shorted open. Amp is now powering up and functioning as it should.
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