B52 AT100 amp troubleshoot

[mjharrison7]

Hello, I’m looking to get some advise on a used B52 I just bought. So I turn on the amp, turn on the stand by and when my setting is at tube A, nothing. When I’m at tube AB, nothing. When I go to solid state, I get sound. What am I missing? Power tube fuse seems good but not definite. All tubes seem like the light up.


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[chadd]

Re: B52 AT100 amp troubleshoot

Since it works on solid state, it could be that your rectifier tubes are shot. That would be the best case scenario in my mind. Otherwise, you have a problem with the switch (not the worst thing in the world) or you have a problem within the circuits that are only active on those two settings (real pain to troubleshoot).

 

[jeremy]

Re: B52 AT100 amp troubleshoot

the light from the tubes are the heaters which run on 6.3v ac. the tube recto supplies the high voltage dc. id start with replacing the tube rectifier

 

[mjharrison7]

Re: B52 AT100 amp troubleshoot

So, turns out, I opened it up and I found a power tube that was loose. I bought this used and it was shipped and it must have gotten loose during transit.

However, I jammed on this thing for a couple hours at show and the tubes got REALLY hot. Any thoughts on an amp getting over heated???


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[blaise.brown.7967]

Re: B52 AT100 amp troubleshoot

So, turns out, I opened it up and I found a power tube that was loose. I bought this used and it was shipped and it must have gotten loose during transit.

However, I jammed on this thing for a couple hours at show and the tubes got REALLY hot. Any thoughts on an amp getting over heated???


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CHECK THE TUBE BIASING.

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[mjharrison7]

Re: B52 AT100 amp troubleshoot

CHECK THE TUBE BIASING.

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Any suggested YouTube videos on how to check that?


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[blaise.brown.7967]

Re: B52 AT100 amp troubleshoot

Any suggested YouTube videos on how to check that?


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THERE IS ONE THAT I REMEMBER. HOW TO BIAS A MARSHALL DSL 100 H. NOT A B-52 ,BUT THE PRINCIPLES REMAIN THE SAME.

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[Gtrjunior]

Re: B52 AT100 amp troubleshoot

The eurotubes website had a couple of biasing vids.

 

[jimman]

Re: B52 AT100 amp troubleshoot

Those B-52s are known for getting hot. I have a buddy who has one, and no matter what he did with the bias, that thing still gets really hot. It is a good sounding amp though, especially for how little you can get them for.