help needed - installing 80pf cap in my Valve Junior Head

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Lution, May 16, 2006.

  1. Lution

    Lution Member

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    I've seen where some VJ owners are installing a 50-80pf capacitor into the empty C3 spot. This gives the amp some more high end which helps this darker sounding amp.

    can anyone possible show me how to do this in detail. I'm a good solderer, I've just not tackled installing a cap into a spot that's ready for it.

    thanks very much. just need some guidance.

    -Lution
     
  2. Steve Dallas

    Steve Dallas Supporting Member

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    I haven't seen a Valve Jr yet, but generally speaking, you would do it something like this... You normally have to remove the board or at least enough components to be able to turn the board over. Fashion the cap so you can stick the leads through the holes. Using moderate heat on your iron, heat up the cap lead first, then roll the iron down to the pad and apply the solder. Do this fairly quickly on a PCB to keep the pad from lifting. Once you have soldered both leads, snip the excess wire off, then reinstall everything.
     
  3. Geetarpicker

    Geetarpicker Member

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    Pull both tubes first as the spring retainers will bend the PC board if you start to unscrew the board first. Then unscrew all the PC board screws which will probably be very tight. You should be able to carefully tilt and lift the board enough to install the cap. The head version of this amp has bleeder resistors so the power supply caps should discharge quite quickly on their own. I can't remember for sure if the head version has actual holes for the "missing" cap. I think I straped mine up top across the resistor. This mod really helps the tone so it's worth the effort!
     
  4. Lution

    Lution Member

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    awesome. Thanks. Looks like I'm going to have to install mine across the resistor at R6 since there is no empty slot on this head. I could only find a 100pf ceramic cap in town here so I'll give it a shot. I'll post results tonight.

    -Lution
     
  5. Lution

    Lution Member

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    the mod is complete.

    I soldered my 100pf cap to each side of the resistor in R6. Looks sort of like this:
    [​IMG]

    I put it back together, plugged in, and let it warm up for 30 min. I didn't get to play with it very long, but I seem to have gotten some more juice up top and some more low-end definition. A worthwhile mod. :cool:
     

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