Vintage Synth Repair

What you are saying is of course correct, unfortunately that is not the
whole story is it?  We don't have the PCB or the transformer here so we
cannot assume that there isn't a wire link added to match the cct diagram,
or the possibility that the manufacturer actually used a transformer where
the centre tap is internally connected.

 

Having said all this if the two rails are in fact isolated from the this
could answer why when checking continuity on the secondary a measured value
of several megohms was found, if the test applied the prods to the outer two
ends of the windings.  The measurement would then be via the diodes of the
rectifier.

 

Whatever we are suggesting the PCB does not match the schematic so I would
be very wary of relying on either.  I'd prefer to rely on fundamental
principles.

 

Regards

Brian G3OYU

 

From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Malte Rogacki
Sent: 03 June 2011 3:10
To: vintagesynthrepair@yahoogroups.com
Subject: RE: [vintagesynthrepair] Re: Crumart Trilogy replacement power
transformer

 

  

At 13:36 Uhr +0100 03.06.2011, Brian wrote:
> I suggest that you look at the schematic again - together with the page on
> which the various circuit designations are quoted - you will see that the
>ends
> of both secondary windings ARE in fact common and they are definitely at
> ground potential. It is also obvious that the outputs of the bridge
> rectifiers and the transformer centre tap are connected together!

No, they're not. Just look at the PCB. It's the last page of the manual.