Vintage Synth Repair

The secondary of the transformer should show low ohms not high.  A 15V
winding could well have impedance of an ohm or two if not less.  What you
seem to be measuring is an open circuit secondary!  This however should not
blow input fuses.  This suggests that the transformer has shorted turns on
the primary - hence you will need a replacement.  A previous poster
confirmed that there appears from the schematic that you need +-12V and
+-15V, this does not have to be in a single transformer, you could use two
separate units.  A small 50VA transformer for each would almost certainly
suffice.

To connect two transformers you would parallel the input windings and of the
secondary windings common the centre tap and then take the 12V and 15V
windings to the PCB to their appropriate connections together with the
commoned centre taps.

This is not rocket science!

 

Regards

Brian G3OYU

 

From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Boddington
Sent: 31 May 2011 7:22
To: vintagesynthrepair@yahoogroups.com
Subject: [vintagesynthrepair] Re: Crumart Trilogy replacement power
transformer

 

  

The psu board could be faulty but I haven't even got that far. Right now
just having the transformer connected to the and power switch (with the rest
of the synth disconnected) still blows the fuse. The primary checked out.
The secondary show something like 3.5 megaohms. That was it. There may very
well be more damage further on but as I said, I haven't got that far yet.