Vintage Synth Repair

You mean 11.98 volts.

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-----Ursprüngl. Nachr.-----
Von: Scott
Gesendet:  18.02.2011 13:41:39
Betreff:  [vintagesynthrepair] Re: Moog 901B oscillator


--- In vintagesynthrepair@yahoogroups.com, "Quazimodo" <noddyspuncture@...> wrote:
>
> Of course -stupid me... now I see it. Thanks for all the replies guys.
> 
> A couple of other things confusing me on this schematic - where it says "selected for 2.45v at TPA..." - are those refering to Q8 and Q9...? And would TPA be the "A" on the base of Q7. Also Q7 says "selected" but with no explanation!
> 
> Finally, what diode could be used for D2 CL-1 ... could that be a IN34 ... ?
> 
> Cheers,
> TOM
> 
> 
> 
> --- In vintagesynthrepair@yahoogroups.com, no freq <no.freq@> wrote:
> >
> > Look, +11,5V is made out of  the +12V and comes from the node formed with
> > R1, P2 and C1, directly on the board. You'll find it in the upper left part
> > of the schematic.
> > 
> > Le 17 févr. 2011 21:57, "Quazimodo" <noddyspuncture@> a écrit :
> > 
> > 
> > 
> > Hi guys,
> > 
> > I have a question about the Moog 901B Osc.
> > 
> > Looking at the schematic here:
> > 
> > http://www.freeinfosociety.com/media/images/4142.jpg
> > 
> > I see the +12v, -10v and -6v points noted - but I am also seeing three
> > points marked +11.5v
> > 
> > Where was this +11.5 derived from originally?
> > 
> > If you look at the connector strip pin-out on the bottom right - there is no
> > +11.5v coming in..!
> > 
> > Cheers,
> > TOM
> >
>From electronic theory , there's 1.2 mA flowing thru R1 and P2
That means there's 10.98 volts at the junction of R1 an P2.

Either the 11.5 is a nominal voltage or they have the wrong value for R1 to get 11.5 volts there. I think it's only used to partially isolate the "11.5" from the reg +12 volts




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