IBM 5155 analogue display fault

[Scott Stevens]

On Tue, 31 May 2005 23:38:06 +0100 (BST)
ard at p850ug1.demon.co.uk (Tony Duell) wrote:

> > agree or not. But it's certainly food for thought, and 5155's are
> > going to be common as muck for a long time to come (second only to
> > Osbornes I think; I don't want to see another one of those damn
> > things in my life!). 
> 
> Actually. I've mever seen an Osbourne... The only portables I have of 
> that sort of size are the IBM 5155 and the HP IPC.
> 
> > It's the irreversable stuff I don't like - people cutting holes in
> > cases or tracks on PCBs to modify them etc.; reversible things I
> > have no
> 
> But PCB tracks can be easily un-cut -- just solder a piece of wire
> over the break. Wire-wrap wire (stripped, of course) is ideal for
> this.
> 

Yikes!

I am the guy who in the past has had to figure out what the HECK is
wrong with a board, where somebody 'just tacked a piece of wire along
the track.'  Such forms of modification/repair often _disguise_ a wiring
defect, and make it _more_ difficult to find the open line.  The proper
rework method (the only one allowed at the Medical Device manufacturers
I have worked at) is to install an obvious jumper wire, and only from
pad/hole to pad/hole.  NEVER just 'tacked onto' a track.  Never 'surface
soldered' anywhere that there isn't a mechanical fit before heat/solder
is applied.  

But I used to do troubleshooting/rework in an environment where the line
workers would DISGUISE their screwups.  Rip out a plated-through hole? 
Tack in a little ring made of #30 wire to SIMULATE the solder pad.  They
did whatever they could to 'get away' with not having to fix something
properly (which would mean drawing attention to the fact that they'd
screwed it up in the first place)  GRRRR.  

Sorry for the rant.