On initial power up all I got was LCD backlighting, no character display or response from buttons. I've seen this symptom occur before in power starved conditions, which is easy enough to troubleshoot with a voltmeter. A day later, before I cracked the case on this unit I wanted to to get a picture of it. Naturally, that symptom went away and gibberish replaced it.
This hints at failure of back-up battery to me, probably coupled with power delivery issues that may be as easy a fix as redressing the interior wiring connectors. One thing has always bugged me about these gibberish displays, that I cannot recreate the character strings on an operational unit.
Circa 1990 through hole digital construction. Judging from the chipset the upper PCB looks to support the analog signal path while the larger board is populated with digital ICs.
A closer look at the PCB reveals what appears to be caustic potash (potassium hydroxide / electrolyte) corrosion simulating snow drifts at the legs of the ICs, indicating that this unit needs a little more help than replacing the backup battery and exercising the ribbon cables. Thankfully this unit is disassembled with ease, so washing the PCB will be a snap.
After which it's probably looking at a re-cap.
2 comments:
How did you make out with this? I have the same unit with same problem of garbage on the lcd. It is also easily overloaded and distorted by input signal. I've cleaned the ribbon cable contacts and tested the electrolytic. The voltages at the regulators are correct. Thanks!
I'm under the impression that cleaning it off didn't fix anything with mine. I have passed signal, and to a degree have saved programs - but, the effect it produces is not what I would consider normal.
Mind you, I'm an experimental musician, so it *could be* that everything would go right after a factory reset, but it's such a grainy noise machine I've opted to leave it as is. I'm guessing that's not a big help, apologies & good luck!
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