WTB: Tower case for IBM model 80, 60 or 65 (PS/2)

[Tony Duell]

> 
>  On 9/21/2005,  jpero at sympatico.ca  wrote:
> 
> >I was advised that to change this 220VAC unit to 115VAC would 
> >not work even I knew what exactly to do just install voltage doubler circuit.
> 
> I got the same story from an IBM marketing rep when I wanted to take 
> an (original) US-use PC to India to run on 220v 50Hz.  He was right, 
> but for a reason that I hadn't considered.  
> 
> In the old 60w PC power supplies, the fan is AC-operated and is 
> specific to the line voltage stamped on the nameplate.  I simply 

Interesting...

The IBM PC and PC/XT power supplies that I've seen over here are, of course, 
designed for 230V mains. I am pretty sure they're made by Zenith. From 
what I remember, the fan is a 12V DC one but there is a mains-frequency 
transformer with a 115V primary (!) connected between one side of the 
mains and the centre-tap of the mains smoothing capacitors. A bit of 
thought shows this is OK...

There is an internal link that converts the input rectifier to a voltage 
doubler and in the process connects this transformer across the mains. In 
other words it sets it for 115V.

The PortablePC is similar, but there's a user-accessible switch to set 
the input voltage. It does much the same as the intenral link on the 
other supplies.

-tony