Fender Twin Reverb Click and Knob repair

Discussion in 'Glowing Bottle Tube Amp Forum' started by pckeen, Jun 3, 2020.

  1. pckeen

    pckeen NEW MEMBER!

    Mar 14, 2017
    This Fender Twin Reverb has come up for sale for $800. Recent model Twin Reverbs in decent condition go in the region for around $1000-$1200. I don't know the year but the seller thinks it is a 1972-1974 model that has had some upgrades / repairs over the years. The seller believes the reverb box was replaced, and believes the speakers were replaced with Celestion G12 Vintage 30 8 ohm speakers.

    Issues are - cosmetically, it's in rough shape. I would be inlined to replace the tolex and speaker cloth. The tubes look new - they were likely replaced. Clean channel sounds fine. The vibrato channels have a click.

    So - buy it or pass on it? What's involved in this repair and does anyone know the fix?

    Here is the sound of the click.
  2. boredguy6060

    boredguy6060 Poster Extraordinaire

    Mar 28, 2012
    Sou Cal
    The exact fix varies but the tick likely involves a component that in the vernacular is called the roach, or the bug, because it looks like a bug. I forgot the real name but anyone who knows Fender Vibrato or tremolo knows the component, it’s the heart of the vibrato. It’s not expensive or hard to replace if you can do that kind of work.
    However it may not need replacing. It has a few resistors that control the function of the roach and it could be that one of them has drifted out of spec and is causing the tick. The tick is oscillation coming from the roach which is part of its function.
    If your not use to working in a high voltage ( Lethal voltage) environment then your gonna need to find a tech who services Fender amps and figure on at least $200- 250
    just to fix that tick.
    That is no doubt why it’s been discounted.
    Anyway good luck.
    pckeen likes this.
  3. muchxs

    muchxs Doctor of Teleocity

    Aug 14, 2004
    New England
    The hassle with the roach is it's too close to the trem channel input.

    The technical term for the roach is it's a photocell or an optical coupler. Mostly it's a flashing light bulb.

    Just what you want one inch from your sensitive audio stages.

    :rolleyes: :rolleyes: :rolleyes:

    There is quite a bit of difference between a '72 and a '74. If it's a '72 I Might take a swing at it. I can't get excited about an $800 '74 with changed speakers and a trem tick. I could easily put more into that amp than I'd ever get out of it.
    Paul G. and Wally like this.
  4. Paul G.

    Paul G. Friend of Leo's

    Mar 17, 2003
    Rhode Island
    Trem tick can easily fixed, inexpensively. On the other hand $800 is high for this amp, in this condition.
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