Smoking Resistor B52 AT100

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Smoking Resistor B52 AT100

Postby ep1966 on Mon Mar 18, 2013 4:49 pm

Hello All,

I have a B52 AT100 Head every time I take it off standby it smokes R137. R137 is 1.2k 1 watt that couples B+2 and B+3 together in the power supply sections. I was wondering if a bad cap in the filter networks would cause R137 to burn out. Try to up load the schematic but the forum stated pdf file not allowed.
Thanks for any help or thoughts
ep1966

OK converted the pdf to jpg try to up load it got a message "board attachment quota has been reached." just my luck :D
http://music-electronics-forum.com/t9765/ Link to schematic 2nd post down.
ep1966
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Re: Smoking Resistor B52 AT100

Postby ep1966 on Fri Mar 22, 2013 2:57 pm

Well I do believe that this is my first post that didn't get a response. :D But I did figure it out, turned out to be a shorted reverb tranny.
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Re: Smoking Resistor B52 AT100

Postby madjackhatter on Sun May 26, 2013 4:08 pm

I'm not entirely sure but caps are probably as good a place to start as any. 1w seems like a really low power rating for a zister between filter caps though. Most amps seem to hover in the 2-5w range. If something in the chain isn't dissapating current to ground things can heat up in a hurry. Have you checked your B+ current and voltage off the rectifier and compared to known values ? Good luck chasing down the demon....
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Re: Smoking Resistor B52 AT100

Postby madjackhatter on Sun May 26, 2013 4:11 pm

R 137..!?!..damn, that thing has a lot of components :shock:
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Re: Smoking Resistor B52 AT100

Postby ep1966 on Thu Feb 13, 2014 5:47 pm

madjackhatter wrote:R 137..!?!..damn, that thing has a lot of components :shock:

Sorry haven't been on in awhile and yes it does. Yell it was a shorted reverb tranny causing the current draw to smoke the resister. Replaced the tranny with a after market Hammond that is a much better transformer then the stock one and about 30 dollars cheaper then getting it form B52. I got the tranny from Antique Electronics I think it was around 13 dollars. If I remember correctly it was there replacement for the Fender Deluxe. I like the head so much after I fix it I bought it from the guy and added it to my collection.
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