Vintage Synth Repair

Mica and ceramic caps are extremely stable, so you shouldn't need to mess with them.  Micas are still in limited production, so I wouldn't worry about them.  Ceramics are in HUGE production and are typically used for power bypass, so I wouldn't worry too much about those either.

Electrolytics are the real 'bad-boys'.  I'm not sure how tantalums age.  Anyone?

I've heard strong stories about 4000 series parts "aging" (may be lot/manufacturer related), but never about 7400 series.  The 4000 stuff may have gotten a bad rap due to impurities in the manufacturing processes in use at the time.  I just can't speak to that though.

Hope that helps, just a little.

--- 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 I understand mica is obsolete in terms of current production so I am thinking to replace mica with ceramic if this across the board rework happens.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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