Vintage Synth Repair

> OK I've studied the schematic and agree that only a single centre tapped
> secondary winding is required.  As per your other reply a 15V - 0 - 15V
> secondary will suffice.

I'd go with two separate 15 volts windings! Contrary to most (but not all)
designs I've seen this power supply has separate bridge rectifiers for the
positive and negative rails. The two "inner" connections of the transformer
secondary are NOT connected to each other and are not on GND potential. It
is obvious that only the outputs of the bridge rectifier connect together
to GND.

I think it also has repercussions for the power rating of the transformer
but I would have to look this up in detail.