Power Transformer Added

Discussion in 'The Workbench' started by zebrarock, Jan 10, 2019.

  1. zebrarock

    zebrarock Member

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    Hi,
    i have a Marshall 2203 jcm 800 modded with 4 6550 on the final and 4 12ax7 on the preamp. I know my original PT can draws 7 amps of current to be supplied to all of them and i know that they require 7.6 amps instead.
    Have anyone ever added a small dedicated PT to compensate and draw right amount of current to be supplied to all tubes ?
     
  2. RickyLee

    RickyLee Well-Known Member VIP Member

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    You should be OK I would think as I have thought about this same thing with the old JCM 800 2210. That amp has five 12AX7's and four power tubes. I think they might have shipped them with 6550's?

    Anyway, as far as I know it is the same power transformers in the 2203 and 2210.
     
  3. zebrarock

    zebrarock Member

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    Yes i thought it too, but wanting to implement the change anyway and having to manage 3 types of voltage with std voltage selector(120, 220 240 VAC ) , may have sense to get a small tx rating 240V to 12.6V @2 or 3 Amps, for example, and using 240V secondary wire for 240, and the same wire plus resistors to adjust voltage for 220 and 110 ?
    Sorry for newbie question , it might be stupid but i would like to understand how can i do it.....
     
    Last edited: Jan 15, 2019 at 3:13 AM
  4. RickyLee

    RickyLee Well-Known Member VIP Member

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    I would think you should be able to find a 240V to 6.3V filament transformer for quite cheap. I think Hammond might make some in different current ratings.

    Maybe just go with one to power the 12AX7's only and leave the 6550's on the original heater tap.

    But as for the different voltages you brought up of 220V/110V, you lost me there on what you are trying to do.

    I am figuring your wall voltage is 240V?
     
  5. zebrarock

    zebrarock Member

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    My wall is 240 yes, what i ment before was trying to cover all voltage selector choises with a simple 240V/6.3V tx, but now i found hammond items, as you suggested, which can help me with different voltage rating on primary.
    Yeah this is what i have on my mind...
     

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