[sdiy] power transformer pointer ?

[David Halliday]

Yeah - the Oberheim Xpander uses an internal switching power supply so the
transformer is not anything that you will find off the shelf.

The *good* news is that your problem is 90% probably *not* the transformer.
I had power supply "issues" with my Xpander, bought some schematics from
Mark Glinsky and was able to find the problem.  My house current suffers
from spikes and one of them took out some of the switching circuitry.  I
repaired it and bought an APC 1400 UPS and have not had a single glitch
since then.

If you are measuring the transformer with a multimeter, it will appear that
the windings are shorted since the DC resistance is so low.  This is not the
case when you are operating at the rated frequency ( reactance ).

Dave

-> -----Original Message-----
-> From: owner-synth-diy at node12b53.a2000.nl
-> [mailto:owner-synth-diy at node12b53.a2000.nl]On Behalf Of patchell
-> Sent: Thursday, May 24, 2001 5:44 PM
-> To: Mountain Man
-> Cc: synth-diy
-> Subject: Re: [sdiy] power transformer pointer ?
->
->
->
->
-> Mountain Man wrote:
->
-> > Ohhhhhh  :(   That's disappointing.  I do hope I can find
-> a replacement
-> > transformer, I'd hate to have to ditch my Xpander because
-> of lack of that
-> > single part  :)    The specs of the transformer appear
-> from the schematic and
-> > manual as follows:  single primary winding that takes 13V
-> at 30 Khz.  The
-> > secondary is tapped, rectified and filtered to produce 2
-> +55V outputs, + and
-> > - 12V, +5V (-5V is a feed off the -12V), 2 grounds, and 2
-> 9VAC outputs, a
-> > total of 9 outputs from the secondary.  Any idea of where
-> to look for
-> > something like this?   ANY pointers, no matter how vague,
-> are welcome at this
-> > point.
-> >
->
->     The 30KHz part makes it sound like a transformer in a
-> swticher!? (I didn't
-> notice that in the original post).  This and the voltages
-> make it sound like you
-> are not going to find a replacement.  Transformers for
-> switcheres are generally
-> not off the shelf.
->
->     Not being familiar with this peice of equipment, and not
-> having first hand
-> knowledge of the power supply requirements, I personally
-> cannot offer any more
-> suggestions. :-(
->
-> >
-> > Thanks,
-> > Elby
-> >
-> > patchell wrote:
-> >
-> > >     A lot of time, power transformers in comercial
-> equipment are custom
-> > > made.  Even if you locate the manufacturer, you more
-> than likely won't be
-> > > able to get one.  Your best bet is to find out what the
-> old one did
-> > > (voltages, etc), and find something as close as posible.
->  12 pins doesn't
-> > > sound good.  It probably has two secondaries, with
-> center taps, and two
-> > > primaries, with 0-100-120 taps.  If this is the case,
-> your chances of
-> > > finding something are greatly reduced.  I don't know
-> why, but those kinds
-> > > of primaries are difficult to find on off the shelf
-> transformers (not
-> > > imposible, just difficult).  Sorry to sound so
-> pesimistic, but finding
-> > > just the right transformer is always such a pain.
-> > >
-> > > Mountain Man wrote:
-> > >
-> > > > I need to replace a power transformer in my Xpander.
-> The transformer
-> > > > has 12 pins, and written on it are the numbers
-> "661023"  and  "51420".
-> > > > The service manual says: "power xfmr 30 Khz 8103-TI
-> incon"   I did a
-> > > > search for "incon" and located a company called
-> "Intelligent controls"
-> > > > that makes power reliability equipment - but don't
-> appear to mfg
-> > > > transformers.  None of the electronics places I tried
-> (Mouser, Allied,
-> > > > Newark, Digikey) have Incon in their manufacturer
-> lists.  Can anyone
-> > > > give me a pointer on where to locate this part?
-> > > >
-> > > > Thanks,
-> > > > Elby
-> > >
-> > > --
-> > >  -Jim
-> > > ------------------------------------------------
-> > > * Visit:http://www.silcom.com/~patchell/
-> > > *-----------------------------------------------
-> > > *I'm sure glad Merry Christmas comes just once a year
-> > > * -Yogi Yorgensen
-> > > ------------------------------------------------
->
-> --
->  -Jim
-> ------------------------------------------------
-> * Visit:http://www.silcom.com/~patchell/
-> *-----------------------------------------------
-> *I'm sure glad Merry Christmas comes just once a year
-> * -Yogi Yorgensen
-> ------------------------------------------------
->
->