On Mon, Jul 9, 2018 at 12:27 PM, Jonathan Gevaryahu via vcf-midatlantic <vcf-midatlantic@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. -ethan