Hi All
I have an MF 3.5 amplifier and it it has a serious crackling on the right channel. It bled over to the left a bit but this was fixed by replacing the NE5532 chip on the motorised volume control.
Now it only faults on the right channel. It is a high dc voltage that jumps up and down as I rotate the volume pot. goes from the usual 20 -30mv to 190 + difficult to get it to stay put.
Measuring across the Pre amplifier O/P phonos it is about a 1.3volts.
The caps on the Volume PCB were replaced, and the ceramics tested all OK.
The fault disappears if I disconnect SK5 from the main PCB.
then I can get a 1K tone out of both channels Ok albeit a reduced volume.
So the fault appears to be around the PIC chip perhaps?
All the DC voltages from the regulators are OK and no noise on the rails.
On IC8 Pins 13/14 no noise at all.
Any suggestions would be welcome.
thanks
Phil
I have an MF 3.5 amplifier and it it has a serious crackling on the right channel. It bled over to the left a bit but this was fixed by replacing the NE5532 chip on the motorised volume control.
Now it only faults on the right channel. It is a high dc voltage that jumps up and down as I rotate the volume pot. goes from the usual 20 -30mv to 190 + difficult to get it to stay put.
Measuring across the Pre amplifier O/P phonos it is about a 1.3volts.
The caps on the Volume PCB were replaced, and the ceramics tested all OK.
The fault disappears if I disconnect SK5 from the main PCB.
then I can get a 1K tone out of both channels Ok albeit a reduced volume.
So the fault appears to be around the PIC chip perhaps?
All the DC voltages from the regulators are OK and no noise on the rails.
On IC8 Pins 13/14 no noise at all.
Any suggestions would be welcome.
thanks
Phil
It is availablea at hi fi engine. I had trouble attaching it
sorry, and thanks for the reply.
I can try again if you cannot et it.
Phil
sorry, and thanks for the reply.
I can try again if you cannot et it.
Phil