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2011-02-17 by Quazimodo
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
2011-02-17 by no freq
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
2011-02-17 by Alan Probandt
The +11.5 comes from the 10 ohm resistor and filter capacitor located next to the Tracking pot in the upper left corner. The marking of 11.5v at that point is the source of the voltage for the other markings of 11.5 on the schematic. In the actual circuit it would (most likely) be a little than more than +11.5, but less than +12V.
----- Original Message ---- From: Quazimodo <noddyspuncture@...> To: vintagesynthrepair@yahoogroups.com Sent: Thu, February 17, 2011 12:57:13 PM Subject: [vintagesynthrepair] Moog 901B oscillator 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 ------------------------------------ Yahoo! Groups Links
2011-02-17 by The Old Crow
It is a local reference voltage created by the slight voltage drop off R1 (upper left corner). The other two points connect to that. --Crow
On 2/17/2011 2:57 PM, Quazimodo wrote: > 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
2011-02-17 by Quazimodo
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 >
2011-02-18 by Scott
--- 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
2011-02-20 by Tom Russell
Some "information" on the CL-1 diode that I found here: http://electro-music.com/forum/viewtopic.php?highlight=901&t=46468 Probably a generic (silicon) rectifier would be fine as the author says (not a germanium 1N34) --------------------------------------------------------------------------- Node "A" on the base of Q7 goes to "A" on the connector I'm guesting that "TPA" is "Test Point A" on a transistor matching schematic in a 901 service manual (like in the Minimoog SM, but that one is measuring Vbe for match.) The note is referring to Q8 and Q9. Good luck, Tom --- On Sat, 2/19/11, Scott <painintheamp@...> wrote:
From: Scott <painintheamp@...>
Subject: [vintagesynthrepair] Re: Moog 901B
oscillator
To: vintagesynthrepair@yahoogroups.com
Date: Saturday, February 19, 2011, 8:49 AM
--- In vintagesynthrepair@yahoogroups.com, "André Hartung" <a.hartung@...> wrote:
>
> You mean 11.98 volts.
>
> Sent from my Nokia mobile
> -----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
>
>
>
Yeah...11.98 volts...I have coffee now