"screen mold"

[Jules Richardson]

Andreas Holz wrote:
> Does someone knows this effect, has an explanation of it's source (is it 
> really temperature related?) or how to avoid this problem. Some of these 
> monitors (esp. of a HP9845) are looking so badly, that I don't dare to 
> power on.

It's well-known; a lot of our HP equipment suffers from it too. I don't 
think anyone's tracked down the exact cause yet (Sellam, didn't you 
think you could get a sample of the stuff analysed if someone sent you 
some?)

Whatever the stuff is, it attacks the sealant between the CRT and CRT 
faceplate. I've successfully removed the decaying sealant on an HP 250 
display using a bit of resistance wire and a scrap PC PSU, then resealed 
(edges of the faceplate only, not the visible portion of the CRT) using 
translucent waterproof sealant.

The CRT itself and faceplate were both unaffected by the decay; it only 
affects the sealant between them.

The fact that I only resealed around the edges (it's too difficult to 
apply sealant to the whole screen with home tools without getting air 
bubbles in) means that there's a *little* less protection to the user 
(the faceplate's pretty thin anyway) in the event of a CRT explosion, 
but I figure this isn't a likely occurrance in the first place - and 
having a usable screen's far better than a useless one!

I've seen the same problem on Digico displays, but not much else - it 
seems to mainly get HP screens for some reason.

Anyway, good news is that it an be worked around :) In the case of our 
HP 250 display, there was a lot of moisture trapped between faceplate 
and CRT, so you're probably right in not powering on until you've sorted 
it out, just in case the damp leaks and gets somewhere it's not supposed to.

cheers

Jules