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  • #2039
    Forum Participant

    I have a 2 part question which I think I know the answer to already.
    Working on a Rogers 4621 radio that is getting a very hot transformer during use.
    All voltages look good though and the transformer looks like the wax inside has come out at some time or another.
    Would it still be good or on the way out even with voltage readings being ok.

    Second question is could I replace that transformer with one out of a model 7r732. I belive rogers was using the same transformer then.

    If any infomation please let me know.

    Ed Stone
    Forum Participant

    How hot is ‘hot’. If it is too hot to hold your finger on (>60C) then it is probably running on the hot side of what it should. Some possible reasons for this:

    – you are running a 110v primary tap on 120v on a transformer that was working close to its rating (can be a problem for many sets). Can be solved with a shunt transformer, dropper reisitor or back to back zener diodes in the primary circuit;

    – there is a fault in the transformer (shorted windings) – check to see you have approximalely equal AC voltages on either side of the HT secondary winding (if not, likley some windings on the lower voltage side are shorting, causing the overheating). Heater windings rarely short;

    – there is a fault in the set: most likley a very leaky smoothing capacitor(s) in the power supply or faulty recifier tube – check the HT current draw

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