Dodgy IBM PC Convertible power supply

[Tony Duell]

> 
> 
> I've got a couple IBM PC Convertibles that exhibit the same problem with
> their power supply.  When I press the power button (which is a momentary
> switch) it turns on briefly: the disk drive light goes on and the drive
> starts to spin or the display shows brief activity, but in either case for
> only about a tenth of a second.  Sometimes if I hold the switch just right
> I can get it to make it through the entire memory test and up to the point

Is this switch on a PCB (like the PSU PCB)? If so, 'holding the switch 
just rignt' might be flexing the board just right to cure a cracked track 
or dry joint.

This does sound like a mechanical problem, a bad connection, something 
like that.

-tony