23 Oct
2011
23 Oct
'11
11:51 p.m.
OK, I still don't have an answer to the question I asked: has anyone here actually
done this sort of work on a HP 9845? I opened up the monitor, but the part number for the
CRT wasn't in evidence. Given the orientation of the tube, I think it's going to
take major disassembly to find that, to see if I can get a reasonable replacement if
that's the route I choose to go. If possible, I'd like to have my action plan in
place before I tear it down to bare bones, so I can get the job done and reassemble things
before I forget where they go.
I've been playing with other aspects of the device and it's all sorts of fun. I
did some simple graphing, which is delightfully straightforward. Something I read
suggested an experiment, and I discovered that it is in fact possible to make changes to a
program *while it is running." For instance, I did a simple PRINT "HELLO"
loop and while it was running changed the line to PRINT "GOODBYE". The output
promptly changed when I stored the new line. I also learned that the capstan rollers in
the tape drives are, predictably, mush, and I have a DC100 tape cartridge to clean out.
-- Ian
________________________________________
From: cctalk-bounces at classiccmp.org [cctalk-bounces at classiccmp.org] On Behalf Of
Tony Duell [ard at p850ug1.demon.co.uk]
Sent: Saturday, October 22, 2011 12:44 PM
To: cctalk at classiccmp.org
Subject: Re: HP screen screen rot
Indeed it is. I wonder if a CRT with the frotn glass removed, but covered
with this material would be safe?
If one wanted
real implosion protection, it might be worth
investigating some of the mylar window films made for the purpose of
containing fragments:
http://windowfilmdepot.com/protection.htm
That's an interesting idea!
I wonder how critical it is to fill the gap between the CRT and faceplate
with something, though? For the HP 250 it was a non-functional display, but
on a working screen will there be problems if there's any air trapped in
there (blooming or reflections off the back of the faceplate, for example)
There might be slight reflections, but no worse than with the separate
safety glass used in 1950's TV sets.
In the case of your HP250, even thoguh you are not running it it could
still be an implosion risk without the correctl-bonded faceplate.
I don't know how the faceplates are/were normally
stuck in place at
assembly - did they apply bonding compound to the front of the CRT and then
press the plate into it, or did they suspend the plate in front of the CRT,
seal around the edges, then pour/inject the bonding compound into the
resulting gap?
ALmost certialy they applied the bonding stuff to one of the parts (which
one I can't say) and then put them together.
-tony