Audio system x ion 280.2 no audio in speaker

[Paol]

Goodmorning everyone ! I have a problem with a system x ion 280.2 audio amplifier! The amplifier turns on but no audio comes out in the speaker. I have measured all the mosfets and transistors present and I have no damaged devices but the thing I have seen is that I have no bias voltage on the mosfets! Do you have any scheme or advice for me?Sorry for my bad English Good job everyone

 

[Perry Babin]

Post a good quality photo of the component side of the entire main board and the component side of any driver boards if no one can help.

 

[Paol]

I have already replaced some components to try! With the oscilloscope I noticed that the signal arriving at the ne5532 is very low and distorted

 

[Perry Babin]

See attached.

These amplifiers are a bit odd in the way they use the final op-amp. If you don't know their configuration, the F2-190 may help. Hopefully, someone will have the right service manual.

What is the DC voltage measured directly across pins 4 and 8 of the 5532s?

 

[Paol]

The voltage reaching 5532 is very low! 0.4v! thank you very much for the scheme it will help me! I'll update you if I can solve! Thank you very much

 

[Perry Babin]

The amp is likely in mute/protect mode. The supply voltage is how they control the output.

 

[Paol]

Goodmorning everyone ! Finally it started again 🙂! the problem is the muting transistor where the bias voltage for the mosfets is also taken !! Thank you very much for helping
😀😀

now i will do some control tests but it seems to work