Vintage Synth Repair

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 won't 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 <mailto:fsimon001@...>  

To: vintagesynthrepair@yahoogroups.com ; SequentialCircuits@yahoogroups.com 

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 I understand mica is obsolete in terms of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.

[Non-text portions of this message have been removed]