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    PA 060 Wires Faded

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    payuppal

    Posts : 3
    Join date : 2013-05-31

    PA 060 Wires Faded

    Post by payuppal on Thu Apr 19, 2018 4:02 pm

    Hi, first time poster long time lurker. I purchased some used iron on eBay for my next project. Seems there is a problem with the

    with the wire colors fading out on the Power Transformer. I removed the bells, no help. Used an Ohm meter and got most taken care of.

    The only problem are the two short leads, B+ and the Ground CT. One wire is Red and white and reads 28.7ohms across the Red high voltage

    lead, the other is Blue and white and reads 24.7ohms. I just hope someone has a PT laying around and can check the ohm readings. It must

    be out of the chassis. Thank You very much

    Regards,
    Jim  cheers
    avatar
    Peter W.

    Posts : 930
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: PA 060 Wires Faded

    Post by Peter W. on Thu Apr 19, 2018 4:35 pm

    payuppal wrote:Hi, first time poster long time lurker. I purchased some used iron on eBay for my next project. Seems there is a problem with the

    with the wire colors fading out on the Power Transformer. I removed the bells, no help. Used an Ohm meter and got most taken care of.

    The only problem are the two short leads, B+ and the Ground CT. One wire is Red and white and reads 28.7ohms across the Red high voltage

    lead, the other is Blue and white and reads 24.7ohms. I just hope someone has a PT laying around and can check the ohm readings. It must

    be out of the chassis. Thank You very much

    Regards,
    Jim  cheers

    Do you have any means of testing the transformer, or a good VOM and some skills?

    color/color is a pair.  color-color is a marked wire.

    As I remember, sitting here in the office, the power leads are both black.
    Filament leads are green/green and brown/brown.
    5AR4 filament is white/white.
    Red/red is to the 5AR4 plates.
    CT of the B+ coil is red-yellow  COULD BE RED-WHITE IN YOUR CASE
    Bias supply is red-blue COULD BE BLUE-WHITE IN YOUR CASE

    So, separate all the wires, and connect the black leads to an AC power-supply, even 120 VAC if you may do so safely.
    Red-Red should give you approximately B+.
    The CT to either red wire will give you 1/2 of B+.
    The "other" wire will give you 90% +/- of B+ to one red lead, and about 10% of B+ to the other.  

    Use great care when doing this, and do not allow yourself into the circuit, or between a lead and any ground.

    Best of luck with it!

    payuppal

    Posts : 3
    Join date : 2013-05-31

    Re: PA 060 Wires Faded

    Post by payuppal on Thu Apr 19, 2018 11:05 pm

    Thank you, I scanned the forum pretty good and had seen the info you posted. I also saw a post that showed an Output Transformer

    in Ohms by Bob. So I was hoping for a PT in ohms as well, again thank you for you time......

    Jim
    avatar
    Peter W.

    Posts : 930
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: PA 060 Wires Faded

    Post by Peter W. on Fri Apr 20, 2018 8:39 am

    payuppal wrote:Thank you, I scanned the forum pretty good and had seen the info you posted. I also saw a post that showed an Output Transformer

    in Ohms by Bob. So I was hoping for a PT in ohms as well, again thank you for you time......

    Jim

    There are several issues with using just ohms for testing a transformer.

    The first of which is that with early Dynaco stuff, there is sufficient variance within the universe of power transformers that only a range may be give, not a hard, specific reading.
    Then, there are variances in instrumentation. Which also broadens that range.

    Cutting to the chase, using just ohms is *fine* if one is testing *that* transformer of itself.

    green/green and brown/brown should read approximately the same.
    black/black should have a low-but-not-zero reading.
    white/white should have a low reading.
    Take the red/red reading.
    CT to either red should be approximately the same.
    Bias-Supply to one red will be a low reading.
    Bias-supply to the other red will be a much higher reading.
    The totals of these two readings should approximately equal the red/red reading.

    There should be no conductance between windings.

    If all of the above obtains, there is a 95%+ chance that the transformer is fine, irrespective of the actual readings.

    Writing for myself, I will ohm-out a transformer first, just to make live-testing more predictable. And as I have a variable AC supply, I will typically test at some proportionately lower voltage first before running at full voltage. Internal faults sometimes do not show except under actual voltage. But, the best-and-only certain test is at operating voltages with a fine-pitch watt-meter/ammeter in the circuit as well.

    payuppal

    Posts : 3
    Join date : 2013-05-31

    Re: PA 060 Wires Faded

    Post by payuppal on Fri Apr 20, 2018 12:22 pm

    Hi, now that will work for me, thank you

    CT to either red should be approximately the same.
    Bias-Supply to one red will be a low reading.
    Bias-supply to the other red will be a much higher reading.

    Regards, Jim

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