I don't think that that is the problem. I'm getting 22 volts off of the rails and a voltage drop of 15 volts across the zener. I would think that that 820 would go out if it was shorted. Oh, I'm getting a 1.2v or 1.8v drop across the 820 ohm resistor. (I didn't look at the board layout to see exactly which one is which)
Thanks for the response.
--- In yamahacs80@yahoogroups.com, "zenithaudio2003" <zenithaudio2003@...> wrote:
>
> Hi i ad a similar problem with a minimoog , it was the zener refence zener diode , i think on the cs-80 it is the d715 , it is thermaly insulated . Look if this zener is not open or shorted . On the mini ps the diode didnt seem bad , but this was the problem .. I hope it will help .. here is the picture ... http://www.flickr.com/photos/31603983@N05/3387453213/
>
> --- In yamahacs80@yahoogroups.com, "mborish_2000" <mborish_2000@> wrote:
> >
> > You mean a BD234 or 2sd234 right? Thanks for responding Kent. I'm going to give it a shot. On another note, do you sell extraction springs for the ribbon controller?
> >
> > -Mike
> >
> > --- In yamahacs80@yahoogroups.com, kent spong <kent_spong@> wrote:
> > >
> > >
> > > Hi
> > >
> > >
> > > I would replace the tip31 and instead use a BD324
> > >
> > >
> > >
> > > > ,
> > >
> > >
> > >
> > > To: yamahacs80@yahoogroups.com
> > > > From: mborish_2000@
> > > > Date: Thu, 26 Mar 2009 16:44:01 +0000
> > > > Subject: [yamahacs80] Help with 8.5v rail
> > > >
> > > > A few months ago, I accidentally shorted the 8.5v rail to ground while calibrating VR723. (I know, I'm an idiot.) Common sense told me to take out TR709, check it and replace. I replaced TR709 with a TIP31C as well as IC722 and still have the same problem on the output: 3 volts and some change. I Removed the lead and get about 7.8 volts with the PSU unloaded and a little bit less with a 1M ohm load. The metal oxide resistor reads about 8/10 of an ohm in circuit.
> > > >
> > > > I was wondering if anybody could post what some of the voltages are in their CS-80 PSU for me. It would be nice if I could have the voltages from TR711, TR710, D713 and IC722
> > > >
> > > >
> > > >
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>