[sdiy] VCS3 PSU

[steve thomas]

Hi Magnus nice to hear from you! Synthi AKS restoration ..thats the way to
go!
I have a question concerning the power regulator circuit on board A of the
VCS3 (similarly for synthi A?) which maybe you  or other list members could
help.On the unit I have,  there were no heatsinks on any of the power
transistors in this circuit (there are 2,  BFY51's in the VCS3 mkII psu
board). When i found one of them was dead ..i replaced it WITHOUT a heatsink
and it lasted for a minute before overheating to the extent that the plastic
transistor holder fused to the BFY51!
The same fate apparently fell the one I replaced, because that too had its
holder melted. Then it dawned on me that
heatsinks might help. I fitted some and still one of the BFY51's runs  VERY
HOT but the +12/-9v supply appears stable. Is this normal for VCS3's /synthi
AKS's  or do i still have problems somewhere?

Thanks for any input

cheers
steve


Synth-DIY pages:-
http://monopole.ph.qmw.ac.uk/~thomas/synthdiy/index.htm
----- Original Message -----
From: Magnus Danielson <cfmd at swipnet.se>
To: <s.thomas at qmul.ac.uk>
Cc: <synth-diy at dropmix.xs4all.nl>
Sent: Monday, December 03, 2001 11:37 PM
Subject: Re: [sdiy] VCS3 restoration project


> From: "S.Thomas" <s.thomas at qmul.ac.uk>
> Subject: [sdiy] VCS3 restoration project
> Date: Mon, 3 Dec 2001 18:22:42 +0000 (GMT)
>
> > Hi all,
>
> Hi Steve,
>
> >        I started a VCS3 restoration project a couple of weeks ago. I
have
> > put pics and discussion on my webpages of the repairs/problems
> > encountered etc that might interest you synthi fans out there:-
> >
> > http://monopole.ph.qmw.ac.uk/~thomas/synthdiy/index.htm
> >
> >
> > Hopefully in the next few days I will update the section on my synthi A
> > clone which is near completion. Hope to add some mp3's made by it soon!
>
> Wonderfull. I am fixing up a Synth-AKS right now.
>
> *DO* replace old caps before they get really old.
>
> VCA trimming is a bit difficult to get *really* right.
>
> Cheers,
> Magnus
>
>