Vox DA-5 Power Input

Discussion in 'Amp Tech Center' started by Willie D, Mar 14, 2013.

  1. Willie D

    Willie D Friend of Leo's

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    I hope this is the right section for this question.

    I have a Vox DA-5 miniature modeling amp. I love it.

    However, the input for the power supply is jacked. I have taken it apart and looked for broken solder joints where the supply meets the PCB, and they appear (at least) to be intact.

    It works fine on batteries.

    But I'd prefer to not run it on stinkin' batteries all the time.

    Is it worth having someone look at it? Anyone have other ideas?
     
  2. AirBagTester

    AirBagTester Friend of Leo's

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    That sucks. Do you think it might be the power supply itself?

    I hope mine doesn't die... it's a fun little amp. I was even thinking of adding a speaker output to it eventually.
     
  3. syrynx

    syrynx Tele-Afflicted

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    Willie D, I have a DA5 with an identical or very similar problem. I bought it for my then twelve year old son six years ago, and it worked fine for a couple of years., But then the external power began failing intermittently. My son (who did and does not live with me) discovered that he was able to work around the issue by wiggling the power connector until it worked, then wedging it in place somehow while he played. But, by the time I heard about the problem, that solution was no longer working reliably.

    I opened it up and, like yourself, was not able to spot any broken traces, even with the aid of a magnifying glass. I spent several hours peering, poking and prodding before buying him a replacement amp (a Peavey Vypyr 15, which he loves and which has performed flawlessly through four years of teen abuse).

    As this was four years ago, my memory is a bit hazy, but I do recall clearly that the issue was neither the power supply nor the connection, because I was able to measure the appropriate voltage at points on the circuit board itself. I observed that the wiggling of the power connector was not making/breaking the circuit within the connection itself. What was actually happening was that the wiggling was bending the apron of the chassis slightly, and this bending was occasionally, intermittently restoring the power connection somewhere on the circuit board.

    I have a vague recollection that my suspicions centered on a three legged device, located on the circuit board near the power connection, which may be a voltage regulator. But I wasn't smart enough to figure out any way to test whether this device or one of the connections to it had failed.

    Perhaps your younger, keener eyes and more agile brain can make use of this information.

    I didn't try running this one on batteries at the time, because I didn't have any. Maybe I'll dust it off and do that.
     
  4. jefrs

    jefrs Doctor of Teleocity

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    Test the input socket, wiring and PSU with a meter.

    You want continuity of wiring and volts from the PSU.
    Check the PSU is working. Put the voltmeter on the PCB where you expect volts and work back.
    That way you find the actual fault.

    Flexible PCB are a nuisance. You may have a break on the PCB. That can be fixed by soldering down the track over the break.

    The socket, wiring and even the PSU can be replaced easily enough.
     
  5. Willie D

    Willie D Friend of Leo's

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    Thanks! That sounds like a fun weekend indeed!

    It's not the power supply itself. I've tried another one, and this one works in other things.

    I've tried wiggling it to no avail. There's a fault somewhere, I'm sure. As much as I'd like to take it somewhere and get it fixed (and save myself the hassle) I worry that it would cost almost as much to fix as it would to just buy another DA-5.

    I just got a new (cheap) meter and I need to check it out anyway.
     
  6. jefrs

    jefrs Doctor of Teleocity

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    Cheap test meter doesn't have to be accurate, just indicate volts present or about zero ohms for continuity.

    Taking it somewhere is probably beyond economical repair.
    I don't do this but if it were me I'd have to charge an hour's labour plus parts.
    I can't tell you the going rate my company charges for me, it's scary, but the garages charge maybe £60. DA5 are going s/h for £60

    This is a DIY fix and fairly simple, first find the fault. Here, faulty-faulty ...
     
  7. Alamo

    Alamo Doctor of Teleocity Silver Supporter

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    Hmm, I use rechargeable batteries in mine and get good mileage out of 'em. don't you?

    hope you find & fix the fault with the power supply though.
     
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