Marantz SR 1040, burning new fuses. Amplitude limiting system?

[manfredkallfass]

Dear all,

 I bought a marantz  75 SR 1040  amp 2 years ago.

After 1 year it started "muting" itself for some seconds, mostly when the volume was a little bit high (not THAT high tho). It muted with a sort of "click" - the same sound of when it turns on or off.

It looked like it actually went off during the peaks of amplitude...like a volume protection.

Then at one point it just went bananas and it won't play anymore. It did not even turn on.

I changed one of the fuse, which was burnt, and when i turned it on again it burnt the new fuse.

I have had no time to work on it for one year. Now i have a little time and I would know if your knowledge can let me understand where to start from to repair it...(maybe capacitors are gone...?). If needed i can send you some more details, pictures, ...


The speakers I was using were quit bad, found in the trash: 8 ohm, they handle 10 to 90 W each. 98db/1w/1m as sensitivity if that matters... One of them has a destroyed woofer. 

Thank you, all the best,


manf

[mzacharias]

It was an exceptionally bad idea to use known defective speakers. You now have at a minimum one amplifier channel blown (possibly both channels).

The output transistors for at least the one channel are now shorted; quite possibly other parts such as driver transistors, resistors, diodes, bias transistor, etc damaged as well.

Easy job for an experienced technician, probably challenging for a novice.

[manfredkallfass]

Thanks for the answer, not very encouraging but I will try to look at it if i get some time. Or get a new amp. And a new speaker.