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Bad OT affect bias, cause redplating?

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  • Bad OT affect bias, cause redplating?

    working on a carvin TS100, 50 wattx2 stereo. Channel 1 output low and distorted. Pin voltages on all 4 EL34s identical, or within a few volts. First tube (V6) redplating... swap them... still redplates. Bias way hot on ch1 even at lowest bias setting. Measure OT primaries, ch 1, 19 and 90 ohms, ch 2 89 and 90 ohms. Swap the OTs... now ch 2 is low and distorted and the third tube (V8) redplates. Have I got this right? My first guess was bias problem but the channels have separate bias and the redplating is connected to the suspect OT
    Is it time for a new OT?

    here's a link
    http://www.carvinservice.com/crg/schematics/TS100C.pdf

    just SWAPPED QC1,QC2 AND QC31
    with QC33,QC32 AND QC3

  • #2
    Yes, the OT is shot and causing the tube to redplate.
    Time for a new one.

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