Yamaha DX7 Battery replacement issue

pdman1 · Posted: Sun Mar 03, 2013 4:10 pm Post subject:

No not to ground.
Measure across D4. Put one probe on one end of D4 and the other probe on the other end of D4.
Then switch the probes to measure D4 again. What resistance do you measure?

Gothboy · Posted: Mon Mar 04, 2013 4:11 pm Post subject:

pdman1 · Posted: Wed Mar 06, 2013 4:58 pm Post subject:

You need to use the lowest ohms scale usually 200 or 400 ohms. Sounds like you used the 20 MegOhm scale. Measure again.

Gothboy · Posted: Thu Mar 07, 2013 10:49 am Post subject:

pdman1 · Posted: Thu Mar 07, 2013 4:48 pm Post subject:

Doesn't make sense. You don't get a voltage drop across D4 when measuring voltage. Does you meter have a diode setting? Use this to measure across the diode.

I would desolder what you did and look for open or shorted tracks, pads, etc. Then carefully install your battery holder. Such a simple procedure that is not making sense.

Gothboy · Posted: Tue Mar 19, 2013 8:38 am Post subject:

I'm at it again...removed the battery and cleaned up the area on the backside of the board where the battery goes. I'm attaching some photos of the front and back. You can clearly see where the holder goes and the + and - contacts on the front. My question is in regards to the area on the back where the + goes it's a strip on the right(Looks a bit like a landing strip) is the + supposed to be touching this or is it just for solder and the + tip is in the solder?

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pdman1 · Posted: Wed Mar 20, 2013 5:12 pm Post subject:

You need to clean up the backside of the PCB. Use 1t least 90% alcohol and an Xacto to scrape off all that gunk.
Also looking at the top component side battery minus terminal, you need to make sure you have continuity between the top pad and the bottom PCB pad. It looks like you may have destroyed the via or feed through of the Pad. This via connects the top pad to the bottom pad.

Gothboy · Posted: Sun Mar 24, 2013 10:52 am Post subject:

Cleaned the back of the board, went out and got new rosin core solder. Went at it again and did a re-solder. Still has the same problem so it's off to HiTech I'm afraid. It's apparently just beyond me at this point. Sad

pdman1 · Posted: Mon Mar 25, 2013 5:11 pm Post subject:

OK

as an option, I repair Synths here on the North Shore. I know Lawrence is closer but if they can't do anything let me know.