Vintage Synth Repair

Yeh you can do that but they need to be connected in
parallel to achive 30pf if thats what you want.

For further reading see:
http://www.allaboutcircuits.com/vol_1/chpt_13/4.html

Thanks, Phil.

--- cockandswan <cockandswan@...> wrote:

> thanks a lot! so i already went out and got two 15
> pf caps to replace
> the 30 pf cap (you can do that right?) 
> 
> do you know if they'll be any negative side effects
> of adjusting that
> trim?
> 
> thanks for the advice, i'll let you know how it
> goes! i think i better
> do the test points next...
> 
> -johnny
> 
> 
> --- In vintagesynthrepair@yahoogroups.com, Malte
> Rogacki <gacki@...>
> wrote:
> >
> > > i didn't even realize it but "c2" the capacitor
> hooked to pin 1 and 8
> > > of the op amp is totally broken. classic newbie
> move i guess. fix one
> > > problem and cause two more. so now i'm looking
> in the user manual and
> > > i don't see a value for that part in the parts
> list of board C-1. do
> > > you happen to know what the value of that
> component is?
> > 
> >
>
http://en.wikipedia.org/wiki/Opamp#Class_A_gain_stage
> > 
> > If you're using a modern internally compensated
> opamp this capacitor
> might
> > not even be needed; however if you're using a
> LM301 like in the
> original it
> > is 30pF as indicated on the schematic. Because
> this is a "standard
> value"
> > as described in the wikipedia link it is probably
> not in the parts list.
> > 
> > I don't think this should cause this behaviour,
> though.
> > 
> > There are a few other points but you might first
> want to check out the
> > voltage on pin 3 and 4 of the filter module. Pin 3
> is the output of the
> > opamp (and hence the various modulation sources),
> pin 4 is the cutoff
> > slider.
> > There's also a trimmer (T3) that is used to
> fine-tune the cutoff
> frequency;
> > if that one is completely out of range it might
> affect the frequency as
> > well.
> > 
> > I'm working on a Odyssey Mk3 at the moment myself.
> > 
> > 
> > -- 
> > Malte Rogacki gacki@...
> >
>
----------------------------------------------------------------------------
> > "Don't forget to TURN ON THE SYNTHESIZER. Often
> this is the reason
> why you
> >  get no sound out of it." (ARP 2600 Owner's
> Manual)
> >
>
----------------------------------------------------------------------------
> >
> 
> 
> 



      __________________________________________________________
Sent from Yahoo! Mail.
A Smarter Inbox. http://uk.docs.yahoo.com/nowyoucan.html