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is it ok to replace a dual output transformer with two single output transformers?

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    is it ok to replace a dual output transformer with two single output transformers?

    Hi, some prestory: I was repairing an amplifier - a "Phil Jones Bass". It had some bad capacitors an a faulty power switch. Easy job. However upon putting it back together I screwed up. The connector from the 15V-0V-15V from the transformer is identical to the audio ouput from the preamp board to the poweramp board. I ended up putting +-15VAC into the preamp outputs frying some traces on the circuit board along with the power transformer The transformer is shorted. It blows the fuse immediately even with no load on the secondary.

    Now that's a challenge - luckily the preamp board is mostly standard components I already have on the shelf. I'll start by getting the PSU back up and running and run fuses on the seconaries until I know the amp is stable and working.

    Looking in the parts bin I don't have a suitable replacement for the transformer. Is it OK to replace the broken transformer with one 50-0-50 and one 15-0-15? Should I connect the center taps together? This would be much easier and cheaper than sourcing a transformer that has the exact windings that the amplifier calls for.
    Last edited by amelbye; 08-21-2020, 08:52 AM.

    #2
    Re: is it ok to replace a dual output transformer with two single output transformers

    Usually ok to use separate power transformers but how to hook them up depends on the original.

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      #3
      Re: is it ok to replace a dual output transformer with two single output transformers

      ^ What eccerr0r said.

      Probably will be OK, but don't connect the center taps together unless they were connected together on the original transformer. Seeing how most amps work, I'm pretty sure that the center taps are connected, though. Of course, just verify first.

      That said, even going as far as using two separate (but identical!) 15V AC transformers and connecting them in series to get +/-15V with the middle point as the center tap can also work.

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        #4
        Re: is it ok to replace a dual output transformer with two single output transformers

        There are 6 wires going from the transformer to the main circuit board:
        15-0-15 and 50-0-50. The center of the 50V rail is connected to Ground, and the center of the 15V center is not connected to ground, or at least not the same ground. Perhaps the preamp-board has its own groun reference. I think I'll leave the center taps separate for now and give it a try

        Thanks!

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