Sony STR-7065 Just burned me

Hi.

I did something dumb and got a second degree burn on my finger. It hurts like a crazy right now. Here's what I did.... I just got a Sony STR-7065 off the bay. (dang it sounds fine) Put my meter on the speaker terminals and left channel is 135mv, right is 15mv. Then I noticed that the heat sink for the left channel was pretty warm while the right channel was slightly above room temp. THEN I saw a dingy looking grey resistor(I think) and touched it with my finger for some unknown reason. Immediate burn, immediate blister, hurts like a b**ch, can only type with one hand right now.

The pcb board around this resistor is slightly browned, big surprise. So a few questions.

1. Why is that resistor so hot? Seems like a fire hazard.
2. Should I do a re-cap of the vertical board on the left side and will that fix my issues? Or do I need to re-cap the whole shebang?

Pics attached for fun. You can't see the b*stard that burned me, but it is on a board on the left side, near the speaker outputs, near some light-blue caps...
 

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...Should I do a re-cap of the vertical board on the left side and will that fix my issues? Or do I need to re-cap the whole shebang?...


Good thing you're not a dentist: Patient comes in with a toothache on his right side and you either pull all the teeth on the right side of his mouth or all his teeth...:smoke:

recapping is not a cure-all...
 
Big resistors get hot, that's why they are big , to dissipate heat. That spot in the amp must be dropping a lot of voltage- it's in the power supply I'd imagine. You were measuring dc offset, that won't make the heat sink warmer than the other, you need to find the idle current or bias procedure and set it.
 
So I should start looking for the service manual I guess. I've never worked on the insides before, other than blowing the dust out. Gotta learn some time I guess. I'll start searching and learning. Thanks.
 
Yes. If you get the schematic and post it, along with telling us which resistor you are talking about, you might get some useful information.
 
If one of the heatsinks was getting hot, this is the red flag that there's more to the problem than an overheating resistor.

Measure the DC offset for both channels. See the stickey on what this is about if you're not familiar. I'm betting one channel is waaaay out.

I'd also not run the amp until this is sorted out.

Cheers,

David
 
a word of warning because of the potential of shock you should always unplug and discharge the filter caps before touching anything inside a receiver or any electronics for that matter. if that was a tube amp the resulting shock would have been far worse than a burn possibly fatal. please be careful around electricity. and yes the bias on your receiver must be way off to have one heat sink hotter than the other. try to find a service manual for the bias and dc offset procedure. These procedures do require you to have the receiver powered up though. and get a set of mini grabbers for your multimeter one slip and bang something shorts magic smoke is released. a simple repair turns into major trouble shooting the replacement of potentially unobtainable parts and whatnot.
 
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