I recently purchased a cheap Denon PMA 925R. Problem is, there is no sound in it.
It turns on, and the (not original) remote works perfect and can change input like a charm. Volumecontrol is moving too.
with a multimeter I have checked the transistors I could reach from the top, the seems like working.
what would be the next to check?
I have never done anything like this before, so please tolerate some beginner questions.
It turns on, and the (not original) remote works perfect and can change input like a charm. Volumecontrol is moving too.
with a multimeter I have checked the transistors I could reach from the top, the seems like working.
what would be the next to check?
I have never done anything like this before, so please tolerate some beginner questions.
do you have a schematic and can you read it?
do you have a scope?
one way to chase this down is if nothing is burning when you power it up, feed it some audio and trace through the circuit until you find where the audio stops. fix the section where it stopped and resume tracing.
repeat as needed ...
do you have a scope?
one way to chase this down is if nothing is burning when you power it up, feed it some audio and trace through the circuit until you find where the audio stops. fix the section where it stopped and resume tracing.
repeat as needed ...
That model has a DIP42 microcontroller.... that controls all amp functions. I'd also look at this IC.
In addition, there are 2 comparator/bias control ICs used to "turn" the amp output stage on (one IC per channel).
I repaired one of these some years back - ended up replacing the microcontroller IC, which brought the amp to life. The symptoms were identical to yours... the remote functions were working, volume pot was all good - but no sound because the microcontroller was in an error state. I bought the IC from alliexpress... but it is not available there any more.
This is why I would never buy an amp that depends on these microcontroller ICs. This amp has 3 of them...
Or, I'd buy such an amp only if I could source these critical spares at the time of purchase.
Hopefully, you'll find the problem to be elsewhere.
Here's the schematics - good luck
In addition, there are 2 comparator/bias control ICs used to "turn" the amp output stage on (one IC per channel).
I repaired one of these some years back - ended up replacing the microcontroller IC, which brought the amp to life. The symptoms were identical to yours... the remote functions were working, volume pot was all good - but no sound because the microcontroller was in an error state. I bought the IC from alliexpress... but it is not available there any more.
This is why I would never buy an amp that depends on these microcontroller ICs. This amp has 3 of them...
Or, I'd buy such an amp only if I could source these critical spares at the time of purchase.
Hopefully, you'll find the problem to be elsewhere.
Here's the schematics - good luck