Vintage Synth Repair

Hi,
I would like to replace the aluminum electrolytic capacitors on the 
power supply board of my white face MkI ARP Odyssey. The service manual 
calls for 250uf 50V, but the synth currently has 150uf 50V caps (blue 
Spragues). Any suggestions on which caps to use?
Also - any thoughts on whether to use tantalums to replace the old 
tantalums, or to use aluminum electrolytics instead? Cost isn't really 
an issue.
Thanks in advance!
Jeff

On Tuesday 18 November 2008 20:33, jeffbmoore_2000 wrote:
> Hi,
> I would like to replace the aluminum electrolytic capacitors on the
> power supply board of my white face MkI ARP Odyssey. The service manual
> calls for 250uf 50V, but the synth currently has 150uf 50V caps (blue
> Spragues). Any suggestions on which caps to use?
> Also - any thoughts on whether to use tantalums to replace the old
> tantalums, or to use aluminum electrolytics instead? Cost isn't really
> an issue.
> Thanks in advance!
> Jeff

Are you changing these out because they _need_ to be changed?  Or just because 
they're old caps?

I'm firmly of the opinion that most of the caps that get changed in old stuff 
like this probably don't need to be.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

If the service manual calls for 250uf then that's what I would put in(or a slightly higher value). There were many different versions of the odyssey thought so I would make sure you have the same version as in the manual. I wouldnt have thought it would be too critical.
 
There is nothing wrong with modern tantlums if you want to use them again it's not critical.
 
Phil.

--- On Wed, 19/11/08, Roy J. Tellason <rtellason@...> wrote:

From: Roy J. Tellason <rtellason@...>
Subject: Re: [vintagesynthrepair] Advice on ARP Odyssey Mk1 power supply capacitors
To: vintagesynthrepair@yahoogroups.com
Date: Wednesday, 19 November, 2008, 6:37 AM






On Tuesday 18 November 2008 20:33, jeffbmoore_2000 wrote:
> Hi,
> I would like to replace the aluminum electrolytic capacitors on the
> power supply board of my white face MkI ARP Odyssey. The service manual
> calls for 250uf 50V, but the synth currently has 150uf 50V caps (blue
> Spragues). Any suggestions on which caps to use?
> Also - any thoughts on whether to use tantalums to replace the old
> tantalums, or to use aluminum electrolytics instead? Cost isn't really
> an issue.
> Thanks in advance!
> Jeff

Are you changing these out because they _need_ to be changed? Or just because 
they're old caps?

I'm firmly of the opinion that most of the caps that get changed in old stuff 
like this probably don't need to be.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

If there are 150 uF caps in it. Use 150 - 220 as long as the voltage rating is at least 25.
Replace Tants with tants.

I have an odyssey II that has some issues but due to an overwhelming amount of repairs in-house here , it will remain a back-burner unit.

Scott  Frye
AudioFixation
Consumer / Pro Audio Repair
Southern VT 

"Resistance is futile but.....
Impedance is much more complex"

I second Roy's opinion below.  I'm yet to see an actual failure in one
of the big elecrolytics in these particular units.  The ones made in
china and the US tend to be weaker over time it seems than ones made
in Japan or Italy though overall.  Eg. almost all old Mallories in
60's Fender amps need changing and many from the 70's.  The caps in
old Roland stuff though or old Crumar stuff...still chugging away just
fine usually.  I worked over a Hammond from mid 70's recently, that
rare synth 102100.  The caps all were a little over spec on the ESR
meter on that one.  And it's pretty noisy and I still need to see if
it's that or something else.  But anyway just a few hints for those
interested.  Don't waste your time shotgunning caps from those makers
in particular and not the ones used in ARP.  Only the Tantalums are
highly suspect and usually are best just replaced without asking
questions.  -Bob

--- In vintagesynthrepair@yahoogroups.com, "Roy J. Tellason"
<rtellason@...> wrote:
>
> On Tuesday 18 November 2008 20:33, jeffbmoore_2000 wrote:
> > Hi,
> > I would like to replace the aluminum electrolytic capacitors on the
> > power supply board of my white face MkI ARP Odyssey. The service
manual
> > calls for 250uf 50V, but the synth currently has 150uf 50V caps (blue
> > Spragues). Any suggestions on which caps to use?
> > Also - any thoughts on whether to use tantalums to replace the old
> > tantalums, or to use aluminum electrolytics instead? Cost isn't really
> > an issue.
> > Thanks in advance!
> > Jeff
> 
> Are you changing these out because they _need_ to be changed?  Or
just because 
> they're old caps?
> 
> I'm firmly of the opinion that most of the caps that get changed in
old stuff 
> like this probably don't need to be.
> 
> -- 
> Member of the toughest, meanest, deadliest, most unrelenting -- and
> ablest -- form of life in this section of space,  a critter that can
> be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet
Masters"
> -
> Information is more dangerous than cannon to a society ruled by
lies. --James 
> M Dakin
>

Obviously I'm not a tech, but....

The power supply is one of, if not the most, important part of an electronic musical 
instrument.  Replacing old components helps increase stability and reliability.  Plus, just 
because a cap isn't bulging or leaking doesn't mean it's not going to start doing that in the 
near future--these caps are decades old, after all!