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Help! My refin's electonics are dead!

Discussion in 'Hardware, Setup & Repair [BG]' started by dryheatbob, Jan 25, 2004.


  1. I just finished putting my Hamer back together, and the electronics are dead, as in no sound. The help I'm looking for is how to go about finding where the short is. My electrical knowledge is limited, so any explanations or tips y'all leave should take this into account. I do have a multimeter, so that's a start.

    A little info I thought would be helpful: it's a jazz copy with VVT knobs. When I took it apart, I clipped the wires from each pup where they solder to the pots and the wires that solder to the jack. This allowed me to pull the pots out and leave all the rest of the wiring between the pots and the ground alone. I figured that'd make putting it back together abit easier.

    Thanks for any help, guys.

    Bob
     
  2. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    It is almost impossible to give you specific help without schematics or pix of the wiring.

    It's almost a certainty that you have made an error in wiring the bass back up. Hopefully, you made a simple drawing of what went where before you clipped any wires. Go back over your wiring with a fine tooth comb. Look for solder bridges that might be shorting the signal to ground. Make sure that you didn't overheat any of the shielded cables and melt the insulation creating a short circuit.

    A quick check to make sure that the input isn't grounded out is to use your multimeter to measure the resistance between the tip of the plug that plugs into the amp and the barrell of the plug. Rotate the volume control while measuring and make sure that the resistance changes. A changing resistance indicates that the volume control is operative. Zero resistance indicates a dead short. No deflection of the meter indicates an open circuit.

    Make these simple checks and post the results and I'll try to help you sraighten it out.

    Harrell
     
  3. Thanks, Harrell

    I'm going to put your suggestions to use, but it may be a day or two. I'm going on about 4 hours sleep and today's my day to watch the kids. I figure fatigue and my lil guys pulling my away to play barbies or trucks isn't a good starting point for trouble shooting(here comes one now- looks like I'm playing horsies in a moment). I'll definitely post results, good or bad.

    The wiring is identical to the jazz schematic on the Stewmac site the only difference is htere are two wires going to the input jack. I did a simple diagram of the wiring, so I'm figuring my poor soldering skills is the culprit.

    What do you mean by solder bridge? Do you mean accidentally soldering a live wire to ground?

    I'm used to using a multimeter for continuity checks and that's about it. any sites out there that'll get me alittle more up to speed?

    thanks

    Bob
     
  4. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    :) :) Sounds like you have your hands full.

    Yes, thats what I mean by a solder bridge. You definitely don't need a lot of distraction when you start to troubleshoot it.

    It should be pretty simple since you have a VOM.
     
  5. Got her fixed!!!

    After spending hours checking and double checking for anything that could've gone wrong, turns out I didn't mess any of it up. The input jack that I had just bought was bad! ARRRGGGGHHHH!

    And it was luck/laziness that turned that up. I was sitting on the couch, bass in hand just noodling away trying to think of what I overlooked. I had the bass plugged into my amp and the amp on(I forgot that I had left it on after plugging in to see if my latest attempt to fix the short had worked). I leaned over my bass to grab some sheet music, and BAM! I heard notes coming through the amp! After twisting the cable a bit, the bass was working perfect. I grabbed another bass and plugged in to see if it was the cable. Nope. The cable was fine. Next day I bought a new jack, soldered it in and no more problems.

    I'd probably still be stumped for a fix if I hadn't inadvertently left the amp on. Or worse, paid someone to find the problem.

    So, thanks again for your help, Harrell.

    Bob
     
  6. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    Great, Bob. I'll bet you know a lot more about the electronics in your bass now. :)

    I'm convinced that troubleshooting the electronics is the hardest part of the bass to troubleshoot. You do realize that you are now one of the very few that can do so, don't you?

    It would be great to "share the wealth" now. Sooner or later someone will make a post asking the same questions that you did. Please share your knowledge. :)

    Harrell S.
     
  7. I'd love to share anything I figured out, but I'm not really sure what I "learned" is teachable. In my case the problem was solved using the "even a blind squirrel finds a nut now and then" approach. If I hadn't left my bass plugged in and the amp on, I'd still be searching for the problem. Failure of a new part was waaayy down on my list of likely problems- poor soldering skills and limited understanding of how electronics was at the top.

    I will add this though: a systematic approach to troubleshooting, electrical or other, is the best. I had eliminated any problems elsewhere in the wiring and felt confident that the problem lay in the output to the jack.

    I guess the best I could do is relay my experience with the the caveat that I got lucky to some degree and to take my suggestions as possibilities, not probabilities. Gawd, how I love dealing in murky vagueness! :p

    Bob
     
  8. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    "I will add this though: a systematic approach to troubleshooting, electrical or other, is the best."

    Text books have been written that say no more than this sentence.
     
  9. I definitely subscribe to the "If it ain't this then it's that - If it ain't that, it's something else!" school of troubleshooting.

    And I have never found a single case where this statement isn't true. :rolleyes:
     
  10. Amen!