AU-alpha607DR and protection ... :-(

[O au-d11mK2]

So i bought an amp I had been searching for ... And when listening to it at the previous owner it had some cracking noise on on channel, we turned it of and switched the loudspeakers. And when we turned it on again It never went out of protection ...

I still wanted it, but when i inspect it now i see black around some resistors . I think they produced to much heat? can i test the board? I think changing the resistors might be a way ahead, or are these juste the symptoms of an other problem....

Pointers would be most welcome

 

[O au-d11mK2]

Hope I don't have to resort to something like this ...
https://hackaday.com/2014/11/13/extreme-repair-of-a-burnt-pcb/

Ann other question is, can i bypass the blackened section? Some say wires sound better than board based signal paths ..
And what should i try to clean the black parts with?

 

[O au-d11mK2]

So , i thougt i had found the scematics ...
No...

 

[pete_mac]

So i bought an amp I had been searching for ... And when listening to it at the previous owner it had some cracking noise on on channel, we turned it of and switched the loudspeakers. And when we turned it on again It never went out of protection ...

I still wanted it, but when i inspect it now i see black around some resistors . I think they produced to much heat? can i test the board? I think changing the resistors might be a way ahead, or are these juste the symptoms of an other problem....

Pointers would be most welcome

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Every 607 that I’ve seen has varying degrees of heat damage here - these components run hot. Whilst it looks bad, don’t assume that this is the source of the amplifier’s protection problem.

 

[O au-d11mK2]

Thanks, there is some comfort in that...
Im stil searching for some service manual on IT though. I have from other threads understood the au-709 was a western equivalent the 911dg was also mentioned.

But have not found info on protestion corcuiot on these either. Found a YouTube on a 9090 regjering to R34/35 ...

 

[pete_mac]

Thanks, there is some comfort in that...
Im stil searching for some service manual on IT though. I have from other threads understood the au-709 was a western equivalent the 911dg was also mentioned.

But have not found info on protestion corcuiot on these either. Found a YouTube on a 9090 regjering to R34/35 ...

There is no 709 model that I can find.

The protection circuit on the AU-X711 and 911DG (along with the schematic for most of the amplifier) should be the closest to the 607DR.