23 Apr
2001
23 Apr
'01
3:44 p.m.
Exactly right. I use an old 360k drive attached to one of the Molex
connectors to get the old ones to kick in - threw away 3 old supplies before
I knew that, long time ago.
-----Original Message-----
From: owner-classiccmp(a)classiccmp.org
[mailto:owner-classiccmp@classiccmp.org]On Behalf Of Tony Duell
Sent: Monday, April 23, 2001 2:38 PM
To: classiccmp(a)classiccmp.org
Subject: Re: Need IBM Portable 5155 power supply
Hi,
The PS in my IBM Portable seems to be dead.
How are you testing it? Most IBM PC PSUs of that period need a load
before they will start up. The PSU on its own will appear to give
no outputs.
I would appreciate it if someone could send me a new
PS!
Would you be interested in having a go at repairing the existing PSU.
From what I remember it's a fairly conventional SMPSU, similar to the one
in the PC/XT machine. You'll need bristol spline keys and tamperproof
torx drivers to get inside, though, and at least a multimeter for
troubleshooting (a 'scope and isolating transformer are useful!). You'll
need the bristol spline keys to get the whole PSU unit out of the
5155, BTW.
If you do decide to go inside, remeber there are dangerous voltages in
there. Much of the circuitry is not isolated from the power line. And
there are capacitors that charge up to a total of 400V (and when the unit
is operational, that circuit can easily supply enough current to kill
you!). Take great care if you do pull the cover.
-tony