Chriswashere
Active Member
A while ago I picked up a pioneer sa-9500 amplifier that , according to the original owner, did not power on. After repairing a cold solder joint or two the amp powered up just fine but now it hums very loudly.
First I figured the hum was a DC problem but there is absolutely no DC on the speaker outputs before, or after, I adjusted everything according to the manual.
At this point I un-coupled the amp and preamp and started to test their individual performance. It seems that most of the humming is coming from the preamp section but some is still leaking thru the main amplifier. Despite this the amplifier section seems to be working correctly when fed from an external source.
All the voltages have been checked and have all been in spec.
Any suggestions? I am new to this and am not sure where to go from here.
Also the power supply has 2 47uF caps that are swollen. Could these have anything to do with this problem?
The issue seems to be ground related but all the grounds are fine.
Thanks.
First I figured the hum was a DC problem but there is absolutely no DC on the speaker outputs before, or after, I adjusted everything according to the manual.
At this point I un-coupled the amp and preamp and started to test their individual performance. It seems that most of the humming is coming from the preamp section but some is still leaking thru the main amplifier. Despite this the amplifier section seems to be working correctly when fed from an external source.
All the voltages have been checked and have all been in spec.
Any suggestions? I am new to this and am not sure where to go from here.
Also the power supply has 2 47uF caps that are swollen. Could these have anything to do with this problem?
The issue seems to be ground related but all the grounds are fine.
Thanks.