----- Original Message -----From: BrianSent: Saturday, July 17, 2010 2:37 AMSubject: RE: [vintagesynthrepair] Re: [SequentialCircuits] Prophet 10 rework
Hi Frank
It depends on the duty each capacitor is designed to perform as to which technology is best suited. However, I would say that if you used polypropylene throughout, the most expensive, you wont go far wrong.
I find your comment re RS a bit odd. I have had a trade account with them since 1968 and know their catalogue rather well and certainly polyester types frequently come in axial pin outs, as do a range of polypropylene.
Regards
Brian G3OYU
From: vintagesynthrepair@yahoogroups.com [mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Frank Simon
Sent: 17 July 2010 3:06
To: SequentialCircuits@yahoogroups.com; vintagesynthrepair@yahoogroups.com
Subject: [vintagesynthrepair] Re: [SequentialCircuits] Prophet 10 rework
The sample and hold circuit has some poly np capacitors plus a few down by the VCA. The schematic only says Poly. Are these Polyester film, Polyester metallized, or Polypropylene film or does it matter which. Everything I see at RS Component is Radial not Axial like the original. I know that doesn't matter but I was wondering about these different technologies.
----- Original Message -----
From: Frank Simon
Sent: Saturday, July 10, 2010 3:10 AM
Subject: [SequentialCircuits] Prophet 10 rework
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 I understand mica is obsolete in terms of current production so I am thinking to replace mica with ceramic if this across the board rework happens.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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Message
Re: [vintagesynthrepair] Re: [SequentialCircuits] Prophet 10 rework
2010-07-17 by Frank Simon
Actually these np caps on the voise boards are EVOX
axials and are probably low risk failures. They just have a vintage look to
them. At first I thought they were paper but are poly. I'll do all the
tantalums first. These polys should last a while shouldn't they?