Vintage Synth Repair

> I am getting an MS50 that at the present time in operating on 220v. Can 
> the current power supply handle 110 and 220. The Manufacturers' Plate 

If it can't be switched between the two voltages, I recommend replacing 
the 220V AC/AC transformer with a 110V one. Even the schematics shows 
two part numbers for the transformer, which I reckon point to 220V and 
110V models.

Anyway, look for a transformer which outputs around 12-15VAC and has 
dual output, this is needed for the +/-15VDC regulator stage. 12VAC 
output, when rectified to DC, might be a bit low according to the 
7xxx-series regulator specs (iirc input should be 3V above the specced 
output voltage), but it should work anyway.. Or well, at least I haven't 
had any problems even if the DC on the input side of a given 7xxx 
regulator has been at least 1V above the output ;). The more in excess 
you go above 3V, the more voltage the regulators have to "lose" 
somewhere (= heat).

If there's plenty of room inside the case you can even leave the 220V 
one disconnected inside the synth and mount the 110V next to it. Just 
take a look at the schematics (google if you don't have them), the PSU 
is about as basic as it gets :)

Hope this helps,
.Arto.