Voltages on 18W build questions

Discussion in 'Amp Central Station' started by bieworm, Feb 18, 2020.

  1. bieworm

    bieworm TDPRI Member

    Dec 18, 2014
    Amp sounds fine, but voltages on V3
    are off spec.

    Looks like the transformer doesn't deliver 2x3.15V ..I measure 2x2.7V
    The platevoltages on V3 are also off... pin 1 = 184V and pin 6 = 130V... Any ideas?
    The cathodes measure 1.43V at pin 3 and 8. This is nearly 50% too much.
    FWIW the amp sounds amazing nevertheless. Plugged in at 4Ohms into the 3x10 VK cab (2.66Ohms)

    Important notice:
    1. since I only have a Hi input on the trem channel, I only put a single 22K resistor between the input and pin 7 on V3 (that should be about right, no?..I copied it from the TMB schematic)
    2. my intensity pot is 5K instead of the 1K on the layout... the reason is that I do not have a 1K available..
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