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Subject: Re: [yamahacs80] CS50 Whine...

From: Bob Stewart <bob@...>
Date: 2014-07-18

Only two fuses on the CS50.
Voltages are all there, but there's this signal sitting on top of them.
Synth works fine other than the whine, and a duff LFO chip.

Thinking it's got to be a duff semiconductor/ IC on the PSU :-(

B

On Friday, July 18, 2014, laurie laurie@... [yamahacs80] <yamahacs80@yahoogroups.com> wrote:
 

are all 3 fuses intact?

 

---- On Thu, 17 Jul 2014 11:14:08 -0500 bob@... [yamahacs80]<yamahacs80@yahoogroups.com> wrote ----

 

Hi


Just servicing a CS50, and it's constantly outputting a whine of about 4120Hz.

Unit came to me a bit battered as the PSU had shaken loose and trashed a few things inside.
PSU PCB had become cracked, so replaced that with a working one purchased from Synthparts.
Recapped the new PCB before I fitted it.

I've done the usual, changed the logic on the KAS board and the S/H board, replaced power decoupling caps throughout etc.

The only difference is that originally it took a minute or so to manifest... now it manifests immediately.

I can see the signal on all power lines.


Any thoughts?


B