ExTech 205t MM repair (strange power issue)

Discussion in 'Technical Repair' started by Fump, Apr 21, 2016.

  1. Fump

    Thread Starter New Member

    Apr 21, 2016
    1
    0
    A while ago my 205t decided to stop turning on at random. Last thing I did with it was test 1.5v batteries, turn it off, and put it back in its drawer. I pulled it out a few days later and... nothing. Turn the dial and nothing happens. Tested the battery, good. Tested the fuses, both good. Tried a new battery and fuses just because I had them, still nothing. Next I took it apart and visually inspected everything. So far as I can tell there is nothing wrong with it, no obvious broken resistors, solder, or cracks. It does, however, look like it was built by a monkey. My 8 year old nephew can solder better than whoever put this MM together. I doubt it's physical damage, this MM has never been dropped, gotten wet, etc. and, considering its assembly, I wrote it off and bought a new one.

    Now for the interesting part: I was watching TV last night and heard a beep. When I investigated, it was the broken MM powering on. It looks like after I put it back together I left it in an on position and it just took days to turn on. It functioned normally until I passed the off position on the switch. It turned off and wouldn't turn on again. I left it in an on position and lo, about 20 minutes later, BEEP. It was on again. I can reliably use it if I give it 10-30 minutes to power on and don't turn the dial to or past the off position.

    Obviously this isn't terribly useful, and I'm certainly not going to trust it for much of anything, but I'm curious as to what is causing this behavior. I'm not averse to desoldering and potentially wrecking it the rest of the way, it's surplus tools now, but if anyone has suggestions as to why it's doing this, how to go about diagnosing why, or fixing it, I'm all eyes.

    Worst case it's slightly more useless than it already is, best case I have a MM better than the current Harbor Freight $3 special to throw in my trunk toolbox and not care about.

    My thanks to anyone with ideas.
     
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