CRT has a strange disease - Printable Version +- HP Forums (https://archived.hpcalc.org/museumforum) +-- Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum-1.html) +--- Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum-2.html) +--- Thread: CRT has a strange disease (/thread-44618.html) |
CRT has a strange disease - Marc - 10-19-2003 Hi,
I'm facing an unusual problem on my 9845's CRT : since a few months, dozens of little white spots developed along the sides of the screen. Clearly they're on the outside of the tube, but they also seem to be under the surface since I can't wipe them off by any chemical or mechanical means. Above it all I'm afraid the problem may get worse as time passes...
Regards Re: CRT has a strange disease - James M. Prange (Michigan) - 10-19-2003 I don't have one, so this is obviously just a guess, but I wonder whether the CRT's glass has some sort of protective coating that's starting to separate.
Re: CRT has a strange disease - Marc - 10-19-2003 Hi James,
Thanks for your answer ! If such a protective coating is used, it is actually glass. That makes me wonder whether the whole tube is not built with some kind of glass sandwich (two layers or more ?). Another fact : I found other spots, apparently on the inner side ! They're dark, hard to locate (need intense lighting).
Regards
Re: CRT has a strange disease - David Smith - 10-20-2003 Many CRTs are built with a protective layer of glass bonded to the tube like a car windshield. This is to protect the user from an imploding tube if it shatters. You might have a problem with the bonding layer. It is usually a clear rubber/plastic compound.
Re: CRT has a strange disease - Dave Brown - 10-20-2003 Marc- This sounds just like the problem I had a year or so back- Basically mould-like stuff in the layer of clear 'adhesive' between the antiglare screen on the tube front and the bonded faceplate on the tube itself. Mainly around the egdes of the screen area.
Hardest part was extracting the CRT from the case in the first instance-I had to get a very long philips screwdriver to reach all the way in from the back of the case to the mounting screws on the two bottom CRT mounting brackets. When reasssembling I just used a very small amount of replacement adhesive-clear silicon rubber- in the corners ONLY of the antiglare screen- the resulting gap between the tube faceplate and the antiglare glass has not caused any lack of visibility etc. While dust etc can now get in that gap it should also be fairly easy to clean it out again. I am considering maybe filling in the gap down both sides of the antiglare glass with silicon rubber as well. That will give a bit more strength to the assembly-and will leave a top to bottom air path that can still be used for cleaning etc as required.
Dave Brown Re: CRT has a strange disease - James M. Prange (Michigan) - 10-20-2003 Keep in mind that there is some hazard involved when working on a CRT.
Don't forget that you can get a nasty shock from the CRT's anode. Even
Regards, Thank you so much ! - Marc Ferrer - 10-21-2003 Hi ! James, Dave, David, I'd like to thank you all for these valuable informations. It's good to know that a solution exists. Doesn't seem to be very easy, but sure, I'll try it some day ! First, I need two important things : spare time, and enough room to work it out safely (these dear old machines take some place...)
Best regards, Re: CRT has a strange disease - David Smith - 10-21-2003 Hello Dave Brown,
Did you ever get your HP9100 working?
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