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Thread: Kay 504 tube amp power transformer specifications

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    Kay 504 tube amp power transformer specifications

    Hi All

    I am searching for the power transformer requirements for my Kay 504 guitar amp. I have a schematic but it only lists the power transformer as T-1 and i would like to purchase a proper replacement. The tubes are 2 X 12AX7 , 5Y3 and
    6v6 Can anyone help ? Thanks Javelin

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    A tweed Deluxe or Princeton Reverb unit would probably work although without the schematic it is hard to know how the voltages would compare. Also the mounting orientation may differ.

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    So it's a single-ended amp. Much like a fender champ with an extra 12ax7 tube.
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    For some reason I thought it said 2x 6V6, but you're right it's single ended with a tremolo. I recently learned that the same transformer is listed for champ and princeton, which surprised me. That ought to do it. I don't see voltages on the schematic, but it is close enough to work in that circuit.

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    Thanks
    The Power Transformer is listed as T-1 part number 1709 but I can not find the actual specifications and there are no voltages listed on the schematic. Still hoping to locate a replacement ...... The transformer was gone when I got the amp .... Thanks Javelin

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    Here's a Canadian source for the Fender replacement: https://nextgenguitars.ca/products/h...ansformer.html

    It looks like a horizontal mount on the tube chart so it might fit without much difficulty.

    I'm not sure what the chances of finding the exact replacement are. Was the Kay amp made by Valco? Could have an equivalent model under other brand names.

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    I'm not sure how old YOUR amp is, but be careful with the high voltage AC winding. Later (S
    Silverface) Champs had about 420V on the plates of their power tube. A replacement for a Champ/Princeton may boost the voltages in your amp quite a bit.

    If I had to guess I'd say your voltages would be more in line with a tweed Champ, so maybe 350 or so.

    Too high voltage may also stress your filtwr caps if they're not upgraded. I'm not saying all this to scare you, but to just be careful. I don't know what 330x1.414 - 50 is, but that would be your rough B+ with the Fender replacement.

    Justin

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    What are the filter caps rated at? Are they original? B+ will be less than that?

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    Kay 504 Filter Caps

    Quote Originally Posted by olddawg View Post
    What are the filter caps rated at? Are they original? B+ will be less than that?
    Filter caps are rated at 475 volts I have tried to attach a photo not sure if it will post Thanks
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    Quote Originally Posted by javelin View Post
    Filter caps are rated at 475 volts I have tried to attach a photo not sure if it will post
    Thanks
    I would “guess” the B+ is near (probably less than) 450 volts.

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    Quote Originally Posted by javelin View Post
    Hi All

    I am searching for the power transformer requirements for my Kay 504 guitar amp. I have a schematic but it only lists the power transformer as T-1 and i would like to purchase a proper replacement. The tubes are 2 X 12AX7 , 5Y3 and
    6v6 Can anyone help ? Thanks Javelin
    https://reverb.com/item/13314887-kay-504-w-tremolo-1950-s-vintage-tube-amp-made-in-usa
    Kay 504 W/Tremolo, 1950's Vintage Tube Amp

    Click image for larger version. 

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    Hammond 272BX

    https://www.hammfg.com/files/parts/pdf/272BX.pdf

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    That would certainly work although the 100mA H.T. is a bit of overkill especially with Hammond's conservative ratings. There are a few more in that series that would also work there; 60mA is probably sufficient. Note that most of these are vertical mounting.

    http://www.a1parts.ca/transformers/H...263_Series.htm

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