$450 for (fixable?) VOX AC30

Discussion in 'Amp Tech Center' started by zanesaddiction, Nov 5, 2014.

  1. zanesaddiction

    zanesaddiction Tele-Meister

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    Considering the local music shop couldn't figure it out. And the closest repairman is over an hour away, it does give me some advantage. His only other option to sell it woulda been scrap it for parts or spend money on gas and repairman..
     
  2. Cleeve

    Cleeve Tele-Holic

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    It's hard to make out, but it looks like the solder joints may be cracked around the pins of whatever jack is soldered to the pads at the upper left of your pic.
    It's a good thing to resolder those as a matter of course anyway, only takes a second.
     
  3. zanesaddiction

    zanesaddiction Tele-Meister

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    Actually...played the amp when I got home...it crapped out and did it again.....here's a better pic

    image-2330222577.jpg
     
  4. brenn

    brenn Tele-Afflicted

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    I didn't realize AC30's were as cheap as they are. I don't know amps like I know guitars, but there seem to be plenty of working ones in that price range. I'd forget that one unless he cut that price in half. Even at $225, I'd only buy it because I like fixing things and I can usually fix anything.
     
  5. zanesaddiction

    zanesaddiction Tele-Meister

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    A great point. I do enjoy fixing things that other people have given up on. It exercises my need to feel thrifty...

    I googled broken fx loop (not ac30 specific) and tried the trick of spraying pot cleaner on a patch cable and inserting it in send/return jacks repeatedly. Played it for 30 more minutes....no problems so far. I'll repeat the process a few more times . If not ...on to the next step...(whatever that is)

    Again. Thanks for input everyone....
     
  6. Cleeve

    Cleeve Tele-Holic

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    [Yeah, do resolder the jacks, it looks like at least one of those leads has a ring of cracked-ness separating the pin from the solder pad, the others may can't be far behind. i like to use a little paste flux on the pad before i hit it with the iron and solder, to minimize the time to heat the joint.
    Be sure that the contact cleaner is safe for plastic, the EPA cracked down on the solvents some years ago, some of the sprays can craze the plastic frames of those jacks.
    A folder over sliver of 2000 grit sandpaper or even some tough paper with metal polish or even toothpaste can get the contact working again, I never had much success with just spraying and jabbing a plug in there, except to verify the jack was whacked before pulling the board out.
     
  7. Johnny Cache

    Johnny Cache Former Member

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    Almost anything is fixable, just depends on how much you're willing to do. In this case it doesn't sound like it would be too hard to repair.
     
  8. zanesaddiction

    zanesaddiction Tele-Meister

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    Ok. I played a show with it last night with the fx loop bypassed and it worked perfectly...

    I think we agreed on a price. $350....I woulda liked $300 but, I'll take it...

    Now on to the fixing part. Retouch up the solder connections and see how that works.

    Again, thanks for the input everyone!
     
  9. codamedia

    codamedia Friend of Leo's

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    Somebody mentioned this earlier but I don't see that you have tried it.

    Put a short cable (pedal cable) between the IN/OUT of the FX loop and then engage the FX loop (ie: don't bypass it). See if it works... I bet it does.

    Those shorting jacks are a known issue on many amps and a jumper is the easiest fix that works every time. Most amps don't have a FX Loop bypass so the jumper is the only cure other than replacing the jacks. At least you would have options.
     
  10. zanesaddiction

    zanesaddiction Tele-Meister

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    I guess I didn't understand... That will FIX it? (Hopefully fix it).

    I thought that was a diagnostic technique. Explain how that might work.
     
  11. codamedia

    codamedia Friend of Leo's

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    Sorry, maybe a bit of a misunderstanding. In theory it is a diagnostic technique, but if the problem goes away there is nothing wrong with just leaving the jumper cable in place.

    If the amp works with the cable in there then the shorting jacks are shot. Knowing the answer gives you options.
    1: clean the jacks (doesn't always work)
    2: Replace the jacks.
    3: Leave the cable in place and never worry about it again. (this is what I have done with many amps over the years. I trust a little pedal cable more than I trust a shorting jack)
    4: Realize the jacks are shot and leave the loop in bypass mode unless you need to use it.
     
  12. Tle4

    Tle4 Tele-Afflicted

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    The Jacks on the FX loop are most likely switching (stereo) jacks. If it works with a jumper in the loop, the inside of the jack that switches when you pull out the plug may be corroded. If it works with the jacks in the loop, you could try cleaning the jacks by spraying contact cleaner on a 1/4" male plug and run it in and out of the jacks to try and clean out some of the oxidation. You could also try rolling up some fine sandpaper and run it in and out of the jack
     
  13. zanesaddiction

    zanesaddiction Tele-Meister

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    My buddy came over and I was unable to reproduce the problem in front of him. We re-soldered the troublesome looking solder joints and gave the fx loop a thorough cleaning.

    Last night I practiced for 2 hours with the amp without a problem.

    Being that I want to resell this, it makes me nervous calling it "fixed" so easily and with such little effort. I will try it one more band practice before I put it up for sale.

    In the meantime , it sounds GREAT! I own a dr. Z maz 38 and am entertaining the idea of reselling that instead . The vox has a bit more gain available than the dr z....thanks all ! ;)

    I will report back if the issue pops back up!
     
  14. Cleeve

    Cleeve Tele-Holic

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    I worked as a tech for some years and those jacks were/are always a problem- both the switch contacts and the solder joints. The metal chassis expands and contracts at a different rate and to a different extent than the printed circuit board, causing just a little stress and flex on the solder joint where the jack's leads are. That, along with whatever stresses happen when the occasional yank on a guitar cord happens, the solder joints crack, but thankfully on that amp it's easy to get to the solder pads, many amps are not so easy.
    Another good thing, since you hand soldered the jacks, the solder connection is way stronger than even the amp's connections were when new.
    Those boards are "wave soldered" and the relative portions of metals in the solder get used up at different rates, so some boards have a better solder metal strength, depending on how often the board assembly contractor corrected the ratios.
    Hand soldering avoids this because the spooled solder is always consistent- plus and actual human is paying attention to verify that the joint looks good.
     
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