Yahoo Groups archive

Vintage Synth Repair

Index last updated: 2026-04-28 23:41 UTC

Thread

Re: [SequentialCircuits] Prophet 10 rework

Re: [SequentialCircuits] Prophet 10 rework

2010-07-17 by Frank Simon

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.
Show quoted textHide quoted text
----- Original Message -----
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 I understand mica is obsolete in terms of current production so I am thinking to replace mica with ceramic if this across the board rework happens.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]

RE: [vintagesynthrepair] Re: [SequentialCircuits] Prophet 10 rework

2010-07-17 by Brian

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
Show quoted textHide quoted text
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]

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?
Show quoted textHide quoted text
----- Original Message -----
From: Brian
Sent: Saturday, July 17, 2010 2:37 AM
Subject: 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 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

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]

Re: [SequentialCircuits] Prophet 10 rework

2010-07-18 by Frank Simon

It appears at one time there was a poly film 150pF by Evox, which is my Prophet 10. I cannot find a poly film 150pF. All I see is ceramic and Mica. Has anyone experienced this?
Show quoted textHide quoted text
----- Original Message -----
Sent: Friday, July 16, 2010 10:05 PM
Subject: 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 -----
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]

Move to quarantaine

This moves the raw source file on disk only. The archive index is not changed automatically, so you still need to run a manual refresh afterward.