Vintage Synth Repair

I could go either way on replacing the ICs. Yes, definitely get those tantalums out of there. I'd leave the mica and ceramic caps alone though. Mica caps have a 60-70 year lifespan, but are prone to DC leakage. I haven't seen this in a Prophet 10, but have in antique radios and tube amps so I'm guess that it takes a long time for leakage problems to show up. And I've never seen a ceramic cap fail.

--- In vintagesynthrepair@yahoogroups.com, "Frank Simon" <fsimon001@...> wrote:
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> Does anyone have a strong opinion on replacing old parts on Prophet 5 or 10 like capacitors and 4000 series and 74LS series ICs. I definately am replacing tantalum but are the highly populated .1uF Z5U caps Mica or ceramic and do they really go bad? I understand mica is obsolete in terms of current production so I am thinking to replace mica with ceramic if this across the board rework happens. I have declared war on my P10 and plan to replace all parts on the PCB3 board (computer board) like caps and logic ICs. There is a guy with a nice website that states the logic IC technology was poor in the 70s with a 6 micron fabrication process versus a current 0.7 micron process that the reliability of the old chips were poor. I figure this is the way to go first before I question the DAC71, which costs a fortune. The way I look at it is it is a rework that probably is healthy for longevity. I am not sure how to troubleshoot the DAC.
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