MC2100 Vented Cap?

[mcdmgb]

I acquired this MC2100 a few months ago at an estate sale. When I powered it up, I got bad noises and a bad smell. I suspect that it also killed the high-mid and tweeter of the ML-1C speaker that was connected to it. I pulled the bottom off today and found a material sprayed around the bottom of the amp. It is heaviest closest to where a can capacitor is located as shown ibn the pictures. There is no package damage to the cap that I can see. Is this an indication that the cap vented?

Thanks

 

[jlovda]

Sorry to hear that. I think this is why Mac service people use a dim bulb tester and a Variac when they get an unknown, old unit. I have never seen a twist-prong cap that had vented but I would assume the phenolic bottom cover would be displaced, cracked or bulging.

 

[dshoaf]

Unfortunately, I do not see anything amiss in the rather blurry pictures provided. The fact that you smelled things is not a good sign. Common failures involving smoke and similar smells would be found on the black finned heat sinks. There are resistors that are known to burn up there, which indicates more serious problems with the amp.

If you have capacitors that have leaked, you'll see clear evidence of it around them. Try for some close ups of the heat sinks and the power supply section where those metal can caps are mounted to the stiffener. Oh, and rest the hand with the camera on something to improve visibility.

Cheers,

David

 

[mcdmgb]

Unfortunately, I do not see anything amiss in the rather blurry pictures provided. The fact that you smelled things is not a good sign. Common failures involving smoke and similar smells would be found on the black finned heat sinks. There are resistors that are known to burn up there, which indicates more serious problems with the amp.

If you have capacitors that have leaked, you'll see clear evidence of it around them. Try for some close ups of the heat sinks and the power supply section where those metal can caps are mounted to the stiffener. Oh, and rest the hand with the camera on something to improve visibility.

Cheers,

David

David,

I tried to get a few better photos. There's nothing extraordinary that I can see except for some burn/scorch marks on the resisters attached to the large can caps. I removed the cage. There's no residue that I can find from something burning. It's just dust.

.