Dodgy IBM PC Convertible power supply

[Vintage Computer Festival]

On Mon, 13 Jun 2005, Tony Duell wrote:

> > 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.

I'm pretty sure it's not that.  I would doubt each board would have come
down with a hairline fracture.

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

That's what I'm thinking, but then maybe not.  I've tried cleaning both
the power connector and the switch several times with contact cleaner, but
that had no effect.  I'm not ruling it out yet, but because of the way
this thing powers on sometimes and not others, I'm suspecting a bad
capacitor or something(?)

Will have to troubleshoot more.

-- 

Sellam Ismail                                        Vintage Computer Festival
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International Man of Intrigue and Danger                http://www.vintage.org

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