Old A/D/S amp care (PQ 40.2)

[Leesi207]

I picked up a few ADS amps the other day. I’m not familiar at all with this stuff but the grease like substance on the wire touching the paper Heat tape stuff and the metal prong that looks burnt does not seem like a good sign. The circuit under the middle prong looks like it has been replaced, however the paper under it looks absolutely clean.
Anyone have some solid guidance as to how to move forward with this? My neighbor has volunteered to help me a bit, he knows networking in electronics but not so much amplifiers.

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[hispls 5,000+ posts]

The thermal paste should be about the same stuff you use to stick a heatsink on a CPU. As you say that burnt clip looks a bit ominous. If this amp doesn't power up I think it's going to be beyond the scope of anybody on this forum to help you get it up and running (normally more stuff than is visibly damaged will have failed).

If you're looking to get these restored by a professional, hit up Stephen Mantz (Zed Audio Corp). He has been designing and repairing amps since the 70s and offers restoration services. Keep in mind on a 20+ year old amp all the electrolytic capacitors are prone to failure and should be replaced regardless of anything else broken.

 

[Leesi207]

I haven’t even powered them on yet. I wanted to take it apart, look at it. And verify something didn’t work immediately blown or just wrong.
Picked up all of these yesterday on Facebook marketplace from a local guy who ended up looking a little suspicious himself

The thermal paste should be about the same stuff you use to stick a heatsink on a CPU. As you say that burnt clip looks a bit ominous. If this amp doesn't power up I think it's going to be beyond the scope of anybody on this forum to help you get it up and running (normally more stuff than is visibly damaged will have failed).

If you're looking to get these restored by a professional, hit up Stephen Mantz (Zed Audio Corp). He has been designing and repairing amps since the 70s and offers restoration services. Keep in mind on a 20+ year old amp all the electrolytic capacitors are prone to failure and should be replaced regardless of anything else broken.

 

[hispls 5,000+ posts]

I haven’t even powered them on yet.

OK, so if you try to power them up use a very small fuse (3A or 5A) on the power cable, then at least if they break right out the gate you won't have enough current available to do any damage to the boards or anything.

 

[wew lad 5,000+ posts]

OK, so if you try to power them up use a very small fuse (3A or 5A) on the power cable, then at least if they break right out the gate you won't have enough current available to do any damage to the boards or anything.

If you're technically inclined you can use a small light bulb in series with either the power or ground to charge the caps to reduce the inrush current, then use the fuse (I'd even say a 1-2a fuse would be fine once the caps are charged) to make sure you're not killing your power supply or seriously f'ing up the amp lol