IBM 5155 Power supply schematics or info

[Tony Duell]

> 
> On Wed, 2005-11-16 at 16:21 -0800, Chuck Guzis wrote:
> > On 11/17/2005 at 12:43 AM Alberto Rubinelli - A2 Sistemi wrote:
> > 
> > >As soon as I touched the trimmer, I discover the problem !! The cursor was
> > >instable !!
> > 
> > Congratulations!
> > 
> > One of life's hard-learned lessons:  On old equipment, pots, switches,
> > sockets and connectors are not your friends.  
> 
> pots normally seem to be OK though *until you touch them*, as the wiper
> still has good contact until it's moved onto a corroded spot. Personally
> I've found it unusual to find one that's failed without even being
> touched. 

I can't beleive you've never had a VT220 with horizontal hold problems. 
If you get that fault, the cure for 99% of them is to pull the cover, 
twiddle the horizontal hold preset back and forth a few times, re-set it 
to the original position, and give it a try. Most of the time you'll get 
a good picture again.

The fact hat the 'right point' is still at the original setting seems to 
prove it's not something else drifting in the terminal. It's bad contacts 
at that preset.

-tony