loss of heater circuit

Discussion in 'Amp Central Station' started by alexwilds, May 7, 2021.

  1. alexwilds

    alexwilds Tele-Meister

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    My homebrew tweed champ quit on me today. Checking the voltages I find that one tube element heater leads coming from the PT is evidently dead; the other is putting out 6 volts AC.
    Everything else checks out.

    Is heater leads failure in Fender amps a thing? I've never heard speak of it. Can one lead fail and not the other?
     
  2. 2L man

    2L man Tele-Meister

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    Did you measure voltage against ground because it looks like other half of 6,3V circuit is shorted possibly by bad tube? Or socket or wiring? First take tubes out and measure voltage again between heater pins.
     
  3. Les Paul lover

    Les Paul lover Tele-Holic

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    I've had to fix my Orange AD15 as the valve heater circuit failed.

    The transformer was fine, but some crimping connectors failed. Removed them all, hard wired it, never had a problem since.

    It might be a shorted valve, it could be the circuit. Find out if the transformer puts it out and where it fails if not valve related.
     
  4. Wally

    Wally Telefied Ad Free Member

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    How did you take the readings? And....how are the tube heaters wired? Did you wire them the way a 5F1 was wired, or did you take both ends to the tube sockets and use a virtual center tap?
     
  5. dan40

    dan40 Friend of Leo's

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    As Wally mentioned, knowing which way you chose to wire the filament circuit will make a difference. I'm betting on a bad solder joint. Are both the 12ax7 and 6v6 cold or is one of them lighting up? Pilot light on or off?
     
  6. Les Paul lover

    Les Paul lover Tele-Holic

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    When my AD15 heater circuit failed, none of them worked!
    The rectifier, on a separate 5.3v tap did work, and that confused the hell out of me until I understood the schematics!!!
     
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