[vcf-midatlantic] Museum report: terminals

Ethan Dicks ethan.dicks at gmail.com
Mon Jul 9 13:46:25 EDT 2018

On Mon, Jul 9, 2018 at 12:27 PM, Jonathan Gevaryahu via
vcf-midatlantic <vcf-midatlantic at lists.vcfed.org> wrote:
> On 7/9/2018 11:39 AM, Herb Johnson via vcf-midatlantic wrote:
>> I saw many "moldy" CRT's - that's when the front of the CRT has a
>> transparent cover that's separating from the glass. Repair means replacing
>> the CRT, which can take most of an hour depending.

AFAIK, it's bubbles in the PVA layer between the face of the CRT and
the implosion protection screen.

> These CRT tubes don't have to be replaced, the CRTs can be very carefully
> heatgunned to remove the front protective glass cover and scrape out the
> 'cataract' goo. I think Ian has done it to a few of them already?

I've done it with a VT220.  You can use a heat gun or a hot wire to
cut the PVA to free the shield from the tube, then it's all cleanup.
You do need to re-install the shield because otherwise the CRT clamps
don't fit really well and the tube slides around.  I used dots of a
thick (1mm?) silicone "tape" on the corners and it worked well.  Just
a small airgap in front of the face of the tube instead of a layer of
what is supposed to be optically clear PVA.


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