Osborne Executive CRT circuitry

Roy J. Tellason rtellason at blazenet.net
Tue Feb 14 14:56:03 CST 2006

On Monday 13 February 2006 11:12 pm, Tony Duell wrote:
> > The monitor itself was apparently made by Zenith,  but I have not yet
> > been able to locate a schematic for that portion of things,  though I
> > have complete tech info on the rest of the computer.  If anybody knows
> > where I might find a schematic of the monitor as well I'd sure like to
> > hear about it.
> How hard would it be to trace out a schematic? OK, Zenith often used
> house-coded ICs which will make things slightly more difficult, but at
> least they're not custom ICs so they can be identified in the end. I
> can't believe a small mono monitor is _that_ complicated.

Well,  since around the time we closed up our shop (April of 1992) I've been 
having to use a lighted magnifier to be able to see stuff that I was able to 
deal with quite nicely before,  I'm not up to it.  Sucks,  but there it is,  
and I just deal with it.

You'd also need to remove some of the stuff from the assembly,  which is 
pretty tight.

And,  shining a strong light through the boards to see where traces go etc. is 
complicated by the fact that Zenith used blobs of hot glue to hold the 
bulkier components in place,  including a lot of the caps,  TO220 
transistors,  etc.

I once tried to acquire a schematic from Zenith,  since we were a ZDS service 
center at the time,  but apparently ZDS knew nothing about this side of 
things,  and I wasn't successful.  I imagine that info has to be out there 

Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

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