Vintage Synth Repair

Ed, Digi-Key Electronics http://www.digikey.com has a
Power-One dual 15 volt 400ma linear power supply, part
# 179-2065-ND for $40.54 

--- Robert Benchic <bobb1956@...> wrote:
> Hi Ed, 
> 
> You most likely have a dead short on either the pos
> or
> neg 15 volt bus. You can verify this with an
> ohmmeter.
> Disconnect the supply and measure from each bus to
> ground. If it's less than a few hundred ohms you
> have
> a shorted bypass capacitor across the bus. Where the
> PS voltage connects to each of the boards in the
> Omni
> you will find a silver dipped tantalum capacitor
> from
> each bus to ground. Change every one of them to an
> electrolytic of the same value. As for the power
> supply you can substitute the power transistors that
> you can't cross with a different package. It's not
> important to use an exact match. If you want to just
> replace the entire supply Digi-Key has new linear
> supplies for around $40. I can find you a suitable
> replacement and get back to you with the part
> number. 
> 
> Good Luck, 
> Bob
> 
> 
> 
> --- Ed Hallborg <ehallborg@...> wrote:
> > 
> > Thanks Massada  for  your input on this.  This has
> > been an ongoing problem...I got this thing
> probably
> > a year ago it looks great but gets no sound at
> all. 
> > I did some checking on it, got the schematics and
> > found that it appears to have a bad - 15 voltage
> > regulator.  So I try and order the part, it has to
> > cross to this and than cross to this and etc. 
> > Finally I get a pair of regulators that should
> work,
> > I put one in and it works momentarily and fails
> > toasting a resistor on the way.  I take it to a
> > local tech...They keep it two months and return it
> > unrepaired, they cant find the -15 voltage
> regulator
> > and suggest designing a new power supply for it -
> > but don't seem eager to do it.  Mainly they tell
> me
> > not to come back unless "I bring in something from
> > after 1970".  So now I'm back where I started with
> > the damn thing sitting in the corner of the studio
> > collecting dust.  At this point I'm looking for
> > anything and 
> > 
> > Regards,
> > 
> > Ed
> > 
> >  
> > 
> >
>
________________________________________________________________________
> >
>
________________________________________________________________________
> > 
> > Message: 2
> > Date: Thu, 11 Sep 2003 10:14:39 -0700
> > From: "masada wilmot" 
> > Subject: RE: OMni 2 Powersupply repair cont...
> > 
> > Hello all,
> > 
> > 
> > 
> > I'm a fairly new lurker on here but I feel the
> need
> > to pipe in on this
> > thread. As I recall, the power supplies on the
> Omni
> > are a simple standard
> > design with no exotic components. If the
> transformer
> > is still OK, replacing
> > the active components would not cost more than $5
> > and you would not have to
> > install a mechanically different subsystem.
> > 
> > 
> > 
> > I've just repaired a Quadra supply that was just a
> > standard
> > 723/op-amp/TIP110-115 circuit. I haven't looked at
> > the Omni for quite some
> > time but I expect that it is the same. Am I
> missing
> > something here that went
> > before?
> > 
> > 
> > 
> > mw
> > 
> > 
> > 
> > PS, a supply that is capable of putting out more
> > amps than you need is
> > normally not a problem. However, beware the
> supplies
> > that require a minimum
> > load on one rail to maintain regulation - usually
> > switchers.
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > -----Original Message-----
> > From: Ed Hallborg [mailto:ehallborg@...] 
> > Sent: Thursday, September 11, 2003 7:35 AM
> > To: vintagesynthrepair@yahoogroups.com
> > Subject: [vintagesynthrepair] OMni 2 Powersupply
> > repair cont...
> > 
> > 
> > 
> > Robert,
> > 
> > 
> > 
> > Here's the only thing I found so far that meets
> your
> > specs.
> > http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem
> > 0> &item=2556349463&category=32720
> > 
> > 
> > 
> > Is this or something like it usable? I have done
> > some google searches and
> > found the whole power supply boards but they seem
> > like they are putting out
> > too many amps. I don't know if thats a problem or
> > not---also the ones I
> > found on mouser.com are about 100$ apiece. That's
> > fine if it will work.
> > 
> > 
> > 
> > Regards,
> > 
> > Ed
> > 
> > Message: 1
> > Date: Sat, 6 Sep 2003 08:36:27 -0700 (PDT)
> > From: Robert Benchic 
> > Subject: Re: Subject: Re: another broken omni 2
> > 
> > Ed, 
> > 
> > You would be replacing the entire power supply
> > eliminating the need to repair the regulator in
> the
> > original. The connections would be easy, positive
> > and
> > negative 15 volts DC with a common ground and 115
> > volts AC. I can find you a supplier and
> appropriate
> > model if you like. 
> > 
> > -Bob
> > 
> > 
> > --- Ed Hallborg wrote:
> > > Thanks Robert,
> > > 
> > > Can you tell me anymore about these? I'm a bit
> > > confused as too whether they will take care of
> the
> > > -15 voltage regulator problem in the omni 2. Do
> > > they bypass the regulator or something. Is their
> a
> > > special procedure to hook them up?
> > > 
> > > Thanks,
> > > Ed
> > >
> >
>
________________________________________________________________________
> > 
> > 
> > 
> > 
> > [This message contained attachments]
> > 
> > 
> > 
> >
> 
=== message truncated ===


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