Need specs for IBM PC Convertible power supply

[Tony Duell]

> > It should only take a second to check for ground, you probably won't even
> > have to open the case.
> 
> Assume I'm dumb.
> 
> How?

OK, first find a connection that you know is logic ground. Things like 
the ground pins of a parallel port, the ground pin of an RS232 port, the 
ground pin of a known chip inside the machine, etc.

Check for continuity (_very_ low resistance in this case) to either 
connection of the PSU connector. If one side of that connector is 
directly connected to the logic ground line, then it's a _very_ good bet 
it's the -ve side of the power supply.

-tony