Burning smell coming from my BFDR

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by AlRob, Jan 25, 2012.

  1. AlRob

    AlRob Member

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    Last night I was rehearsing with my 66 BFDR and after about an hour i began to smell a strong burning smell. I immediately shut it down and unplugged it. I sniffed around and it seemed to be coming from the transformer side of the chassis. Could this be the transformer burning out? The only thing I've done lately to the amp was to install a NOS RCA 12AX7 tube in the V2 slot just last week.
    If this is the transformer does anyone have a suggestion for a replacement?
    Thanks appreciate the help.
     
  2. Blue Strat

    Blue Strat Member

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    First things first. Check the bias on the power tubes and measure the 470ohm screen grid resistors for the power tubes.

    If you don't know how to do this find someone who does.

    Has the amp ever had a cap job? If not, that could be what caused the problem (the bias cap in particular). If it hasn't you need to do that before anything.
     
  3. guitarcapo

    guitarcapo Senior Member

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    It's probably not the transformer. More likely a burnt out cap or resistor along the rail or plates of the tubes where the high voltage is. I'd at least check there first. "All original components" on a 46 year old amp is not a good thing..... contrary to what collectors might tell you.
     
  4. AlRob

    AlRob Member

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    Thank you, I don't believe its ever had a cap job.
    I forgot to mention in the original post that the amp was sounding fine at the time I smelled the burning.
     
  5. AlRob

    AlRob Member

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    Thank you thats good news. I think the amp over due for a check-up
     
  6. Blue Strat

    Blue Strat Member

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    There's a saying in the amp tech world. "The best sounding amps are the ones just about to melt down".
     
  7. Chris Scott

    Chris Scott Silver Supporting Member

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    ...yup, just like 2-stroke racing motorcycles - running better than ever, JUST before they seize, tossing you to the tarmac.:omg
     
  8. Koop

    Koop Member

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    LOL...been there, done that!
     

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