CRT mold

From: Loboyko Steve <>
Date: Sat Feb 12 19:18:19 2005

Sellam Ismail wrote:

>One of the folks
>here (I forget who it was) fixed a monitor with this
>problem by using a heated wire to remove the
>protective outer laminate and replace it

That was me. As dangerous as this was, I did take some
safety measures; firstly, I made a plywood box in
which to mount the CRT face up. (Needless to say, I
wore a heavy long-sleeve coat, safety glasses and a
hat at all times.) Then, I used nichrome wire
(obtained from a hobby shop used in cutting foam),
powered by +12 from an AT power supply as the cutter.
Wooden handles with screws mounted in them held the
wire as I cut through. I adjusted the length of
nichrome to get just under dull red hot (having a
high-current adjustable power supply would have been
better). I worked pulling up towards the faceplate in
order to avoid heating the face of the CRT, which
might have had "undesirable results".

I'm almost sure that some sort of optical quality RTV
was used. It came off easily with acetone - so easy,
that it might even be possible to remove the plate if
you could suspend the tube in an acetone bath face
down for a while.

Upon close examination, I'm certain that what these
tubes experience is mold - the same type of mold that
gets into the double-pane glass used in homes. This
type of mold is actually capable of etching glass!

I reattached the plate with optical (for aquariums)
RTV, around the edges. It dried amazingly bubble-free
and clear. However, this was not in the masked down
field of the 2644A as installed.

The tube came out very well, because the tube didn't
seem to have any serious phosphor burns to begin with
(no screen saver on early terminals). I would examine
a tube for this very closely before even contemplating
this desparate task. I think that there is some valid
question as to whether this tube is as "safe" as it
once was. I will say that the face of the CRT itself
seemed quite thick (it would have to be, anyway). It
may be that the bonded-on plate is an extra measure of
safety or simply for anti-glare purposes.

I should mention, that the ADM-3A tube is fairly easy
to obtain and fairly cheap (I paid maybe $45 USD
shipped from a year or two
ago for each of my two units). You need to get a part
number off of the tube, because my two ADM's used
different CRT's. Naturally, I used original white
phosphor, although they did have interchangeable amber
and green. I have (do at your own risk) replacement
instructions on my website.

Incredibly, had NIB
replacements for the HP terminals about a year ago,
but they were $250!!

-Steve Loboyko

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Received on Sat Feb 12 2005 - 19:18:19 GMT

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