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Old 19th December 2019
  #5
Quote:
Originally Posted by Thisiscobras View Post
Thanks much for your reply. Here's the other half of the story. I'm pretty scared at this point:

I've been trying to fix what was a very small issue on my beloved SCI Prophet 600 for the past month. Simply 1 Oscillator was out of tune. Everything else worked flawlessly. I was methodically replacing parts and testing after each. All was well as I was slowly tracking down the exact problem. That was until last night when I got the bright idea to use my multimeter to try and check/compare IC chip voltages between a good voice and the one I was having a problem with. I checked the direct voice IC chips 4016 (quad analog) and 4053 (multiplexer) for 2 voices as well as 2 small op amp chips in the S/H section. I grounded the negative probe on the metal chassis and used the positive to check the legs of the ICs. Apparently I'm an idiot for doing this and/or I accidentally caught 2 legs at once and hopefully just shorted a chip only. All was well minus the 1 Oscillator prior to this and now when I power on immediately I hear a loud screeching/white noise followed by what sounds like an Orbital CD played backwards and not in a good way. Keys respond as does the membrane panel and display. No matter what I do there is just noise in the background and all sorts of digital vomit. I'm really hoping I simply just fried one of the chips I tested and that's it. I'm in the process of putting together an order to replace the 6 total chips I touched. I'm really hoping just to get a little peace of mind in the meantime that this is likely all I did and that whatever happened didn't spread down the line to other places.
Oh dear - sounds like you have damaged beyond use of that chip. As montions above replace the chip. As a future tip for measuring things in precarious places tag a little bit of wire onto the leg with solder and measure from the end of the wire. If you have clips on the DMM leads there's no need to touch while powered up.