Question from a rank amatuer Valve replacement

Discussion in 'Glowing Bottle Tube Amp Forum' started by North East Al, Jun 3, 2018.

  1. North East Al

    North East Al Tele-Meister

    Apr 7, 2011
    Hartlepool, UK
    Need some advice. I don't have the tools or knowledge to do this myself. Turned on my Laney VC15 and pop, then silence. One of the EL84s was no longer glowing and the 250v fuse had blown. I take it due to valve dying. I've ordered new fuses from Amazon and a matched pair of EH EL84s from Hotrox in UK.. Can I just pop all these in and plug in, or do I need to get the biasing done by someone who knows what they are doing??? I thinks it's class A/B. Thanks experts

  2. VintageSG

    VintageSG Friend of Leo's Ad Free Member

    Mar 31, 2016
    Providing nothing nasty has happened, replace the valves and fuse and enjoy. If you're handy with a meter, and promise not to blow yourself up, check for -11.5V at the junction of R25 & R26. If you follow the trace back, you'll find a bias adjuster marked P51.

    Or take it to someone :)

    Schematic attached in case you're feeling brave or your tech doesn't have it.

    Attached Files:

    uriah1 and North East Al like this.
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