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Testing output transformer

Discussion in 'Tube Audio' started by Ziradog, Dec 7, 2018 at 8:42 PM.

  1. Ziradog

    Ziradog AK Subscriber Subscriber

    Messages:
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    Location:
    Apex, North Carolina
    I'm sure there is a decent thread on how to test an output transformer that is loose (not in an amp), but I have tried several searches without success. Can someone point me in the right direction? Preferably one that does not require specialized equipment. Thanks.
     

     

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  2. Tom Bavis

    Tom Bavis Audiophool Subscriber

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    Ohmmeter is a start. Primary will measure maybe 5% of its AC impedance (so a 10K transformer may be 500 Ohms DC resistance) Secondary will probably read zero, as most meters can't resolve tenths of an ohm. If you don't know the impedance, here's how to measure: https://www.radioremembered.org/outimp.htm
     
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  3. BinaryMike

    BinaryMike Pelagic EE Subscriber

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  4. trobbins

    trobbins Active Member

    Messages:
    490
    Location:
    Melb, Australia
    Ziradog, what testing did you want to do? What test equipment do you have? Were you aiming to determine what an OT is good for - eg. frequency response, power rating, distortion - or just impedance ratio? Do you know it is an output transformer, and if so then what do you know about it?
     
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  5. Ziradog

    Ziradog AK Subscriber Subscriber

    Messages:
    1,067
    Location:
    Apex, North Carolina
    Trobbins, I have found a transformer that came from a Pilot 240 to replace the generic OPT that is in one channel my 240 now. It looks rough, and I want to make sure it is functioning more or less properly. So I know it is an OPT and what the hook ups are supposed to be. I know the impedance ratio. Tools, I have a DMM & a simple oscilloscope, variac, not much else.
     
  6. gadget73

    gadget73 junk junkie Subscriber

    Messages:
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    voltmeter and a variac will get it done well enough. Basically if its not shorted or open, and the impedance rings out right, its most likely fine.
     

     

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