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Old 10th Apr 2007, 6:04 pm   #1
Stewart
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Default Any Cures for Scratched Faceplates?

I've aquired a replacement colour tube for one of my old sets which is believed to have very good emission (unlike the one in the set at the moment)... but the faceplate has quite a number of deepish scratches on it which will be more than enough to spoil the look - set running or otherwise!

Does anyone know if I stand any chance of improving things here? I remember once trying to polish out a small scratch a friend had put on his then new Philips CP90 using diamond cutting paste sold to remove scratches from car windscreens. Despite hours of work (and I mean hours) there was virtually no improvement.

Filling in with the resin they use on windscreen chips then polishing back had crossed my mind - but it all sounds messy, complicated and with uncertain results...

Can anyone offer any other ideas I might try? Or am I wasting my time?
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Old 10th Apr 2007, 6:06 pm   #2
Nickthedentist
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Default Re: Any Cures for Scratched Faceplates?

There used to be ads in Television for companies who did this. I wonder what their trick was?

Personally, I'd try one of the kits that (I think) you can get in Halfords etc. for repairing damaged windscreens first.

Let us know how it goes,
Nick.
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Old 10th Apr 2007, 6:56 pm   #3
peter_scott
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Default Re: Any Cures for Scratched Faceplates?

A bit expensive but I have found this kit very effective even just using manual techniques so you could limit the purchase to the powder.

Product S130

http://www.frost.co.uk/productList.a...frostCat=Glass
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Old 10th Apr 2007, 7:47 pm   #4
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Default Re: Any Cures for Scratched Faceplates?

I had a number of scratched crt faceplates in the days of regunning tubes.
I used a large commercial car polisher and what was known as 'Jewellers Rouge' It is a time wasting and labourious business and can leave a much less noticeable, slight indent in the tube. The trick is to work it over a much larger area than the actual damage. The lead glass is very hard and metal polish has no effect.
In very bad cases car rubbing paste may have to be employed followed by the Rouge. [No Dear not the sort you put on yer face...] It appears to be a very fine volcanic dust. Pummis? I would only carry this out with 'Rimguard' protected tubes. I would not dare with a CRM121B......
Regards John.
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Old 10th Apr 2007, 9:56 pm   #5
ppppenguin
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Default Re: Any Cures for Scratched Faceplates?

It sounds slightly scary even with a modern CRT. The scratches will concentrate the stresses in the glass. As John says, the thought of doing it on a CRM121 or other old and relatively fragile CRT is scary.
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Old 10th Apr 2007, 10:06 pm   #6
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Default Re: Any Cures for Scratched Faceplates?

Quote:
Originally Posted by ppppenguin View Post
It sounds slightly scary even with a modern CRT. The scratches will concentrate the stresses in the glass.
ET's (or was it Steve Beeching's?) recent(ish) book on TV repair implied that scratched tubes were a hazard and should be scrapped

Reading that cause me many sleepless nights, as most of my TVs at the time had come off skips, and so had numerous chips and scuffs on the CRT faceplates. Never had any problems though
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Old 10th Apr 2007, 11:28 pm   #7
Welsh Anorak
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Default Re: Any Cures for Scratched Faceplates?

Hi
I found after much polishing with rouge you get a nice, slightly matt finish which doesn't look too bad. Then you turn the set on.....oh dear! Move your head even slightly and the scratches act like small prisms - admittedly this was on colour tubes. I am however impressed with whatever windscreen companies do - unfortunately I believe it involves drilling a small hole. Not really recommended on your CRT!
Glyn
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Old 11th Apr 2007, 1:23 am   #8
Stewart
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Default Re: Any Cures for Scratched Faceplates?

Thanks for all your thoughts folks. The kit car windscreen kit that Peter Scott linked to looks interesting - and even if it doesn't do the job in hand is bound to be useful elsewhere..

The tube is an A63-11X and should be pretty robust, although I don't think I'll be using a Black & Decker on it as shown in the link just in case! Mind you, when I got rid of a duff A56-120 last year I maybe unwisely decided it would be easier to get rid of as a bag of fragments rather than whole: Aside from the neck, the blows it took with a sledge hammer to reduce the rest of it to dust amazed me - the glass was incredibly thick and tough!

The scratches are a deep enough to present a slightly daunting challenge - but not heavy gouges that would to my mind present a hazard or make the tube unusable and completely beyond saving... I think it was stored for some time on a carpet tile that must have had some grit on it. :-(

I still might experiment with the windscreen chip filler too: I gather this resin has a similar refractive index to the glass and may well reduce or even get rid of the prism effect when the tube is displaying a picture. I don't think these home kits require a hole like the pro ones Glyn mentions? Although aimed at filling holes I can't see why I can't spread the resin along the scratch with a pallette knife. Cutting back the softer resin flush to the rest of the glass should be a much easier task too I hope. If not, then maybe I'll fill the hole my car windscreen has sported for the last few years with it!

One of the problems is that I will have to go to all the trouble of swapping this big heavy tube over and installing it in the set just to support it so I can work on it! Either that or build a supporting frame of some kind. Still, at least fitting it in the set will allow me to prove the display is, er, up to scratch emission wise!
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Old 11th Apr 2007, 8:51 am   #9
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Default Re: Any Cures for Scratched Faceplates?

Hello Stewart,
The A63-11X has a very thick faceplate and is rimband protected of course. It will be quite safe to work on the faceplate with care of course using a buffing mop and rouge. I have never known any tube to implode due to scratches in the faceplate and when I worked in conjuction with a major tube rebuilder, never had a tube fail due to this.
I would not wish to do this with any unprotected tube but we did with a few rare examples with no disasters. Regards John.
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Old 15th Apr 2007, 8:19 am   #10
Mike Phelan
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Default Re: Any Cures for Scratched Faceplates?

AFAIK the windscreen fixers drill a hole so that the clear resin can be injected under pressure to every part of the crack. Not for CRTs!!

Jewellers' rouge (iron oxide) is not necessarily always the same fineness. An even finer polish as used by watchmakers is diamantine, which will polish hard steel, and presumably glass, to a mirror finish.
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