Journey111
Member
Hi All Again,
I have a Polk Audio plate amp for a sub that had a good standby light but when in auto mode or on mode standby remains red and no audio.
Opened it up and immediately saw all 4 secondary filter caps bulged/domed. So we ordered caps and I replaced but still no go.
After further troubleshooting, I found the negative supply for the amp section is missing. The positive supply is there but IMO it seems rather low at 14.5VDC.
Another odd thing is that I can't seem to get any voltage readings off the transformer secondary. Not sure if I'm using the right ground Ref.
Tried Primary GND then Secondary GND on both ac & dc and seems to be nothing. Yet there is +15 and - 15 on the preamp connector along with close to 5V for on/off ( standby?)
and of course a rather seemingly low +14.5V on the amp power rail and no negative volts for the amp rail.
I'm gonna draw up a schematic that should hopefully make sense to someone or myself ... will post when done and include some more pics.
A couple of pics of the SMPS in question.
I have a Polk Audio plate amp for a sub that had a good standby light but when in auto mode or on mode standby remains red and no audio.
Opened it up and immediately saw all 4 secondary filter caps bulged/domed. So we ordered caps and I replaced but still no go.
After further troubleshooting, I found the negative supply for the amp section is missing. The positive supply is there but IMO it seems rather low at 14.5VDC.
Another odd thing is that I can't seem to get any voltage readings off the transformer secondary. Not sure if I'm using the right ground Ref.
Tried Primary GND then Secondary GND on both ac & dc and seems to be nothing. Yet there is +15 and - 15 on the preamp connector along with close to 5V for on/off ( standby?)
and of course a rather seemingly low +14.5V on the amp power rail and no negative volts for the amp rail.
I'm gonna draw up a schematic that should hopefully make sense to someone or myself ... will post when done and include some more pics.
A couple of pics of the SMPS in question.