Voltages on 18W build questions

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

  1. bieworm

    bieworm TDPRI Member

    Posts:
    31
    Joined:
    Dec 18, 2014
    Location:
    belgium
    OMG!!!
    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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