Power Acoustic OVN1-5500D

[S Merlington]

I just got one of theese in today it appears someone has worked on it before..

Amp powers up and produces audio but has a loud squeal along with bass thru the speaker..

The op-amps that appear to have been replaced in the pic are LM393's

Heres the voltage i have on them..

Pin 1:0
Pin 2:0
Pin 3:0
Pin 4:-13.5
Pin 5:0
Pin 6:0
Pin 7:0
Pin 8:13.85


The other 393

Pin 1:-95.8
Pin 2:-95.8
Pin 3:-95.0
Pin 4:-96.1
Pin 5:-96.1
Pin 6:-96.1
Pin 7:-95.6
Pin 8:-82.3

[Perry Babin]

Is the audio clean on C171?

[S Merlington]

Audio Is not clean on C171 and i have 1.30 volts of DC measured directly across the speaker terminals

[Perry Babin]

There is an offset adjustment for the DC.

The audio may not look clean. What you need to determine is if the noise (squealing) is present there (at the input to the class D circuit). If it is, the problem is likely in the preamp circuit. If it's not present, the problem is likely in the class D circuit.