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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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RCA P46720LV Bad Green CRT
Found this set at a garage sale, owner indicated that he had service people
come out and they told him the green "bulb" was bad. I'm taking this to mean the CRT is bad. Given that this set is probably ten years old and a replacement CRT is about $250, I didn't grab it for the $60 he wanted. What do these sets go for in working condition? I do like tinkering however that is a rather expensive tinker in my book. I don't have access to used parts either. Just wanting a few opinions... Would you buy it? Thanks, Kirk S. |
#2
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RCA P46720LV Bad Green CRT
On 5 Aug, 23:43, "Kirk S." wrote:
Found this set at a garage sale, owner indicated that he had service people come out and they told him the green "bulb" was bad. I'm taking this to mean the CRT is bad. Given that this set is probably ten years old and a replacement CRT is about $250, I didn't grab it for the $60 he wanted. Fix the existing crt. Every repair tech I know says its impossible but its not difficult. NT |
#3
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RCA P46720LV Bad Green CRT
wrote in message ups.com... On 5 Aug, 23:43, "Kirk S." wrote: Found this set at a garage sale, owner indicated that he had service people come out and they told him the green "bulb" was bad. I'm taking this to mean the CRT is bad. Given that this set is probably ten years old and a replacement CRT is about $250, I didn't grab it for the $60 he wanted. Fix the existing crt. Every repair tech I know says its impossible but its not difficult. NT There's not much you can "fix" on a CRT without completely rebuilding it, which I suppose is within the realm of a very persistent amature who happens to have a diffusion pump and glassworking equipment but I've not heard of anyone doing that sort of thing at home yet. If the set is HD capable I'd haul it away for free, might even pay 10 bucks or so for it, but if it's only a SD projector forget it, he should be paying you to dispose of it. There's some cool optics in a CRT projection set though if you're into experimenting with that sort of thing. |
#4
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RCA P46720LV Bad Green CRT
"James Sweet" wrote in message
news:hKuti.483$mw4.371@trndny09... wrote in message ups.com... On 5 Aug, 23:43, "Kirk S." wrote: Found this set at a garage sale, owner indicated that he had service people come out and they told him the green "bulb" was bad. I'm taking this to mean the CRT is bad. Given that this set is probably ten years old and a replacement CRT is about $250, I didn't grab it for the $60 he wanted. Fix the existing crt. Every repair tech I know says its impossible but its not difficult. Please, elaborate on this if you would... NT There's not much you can "fix" on a CRT without completely rebuilding it, which I suppose is within the realm of a very persistent amature who happens to have a diffusion pump and glassworking equipment but I've not heard of anyone doing that sort of thing at home yet. If the set is HD capable I'd haul it away for free, might even pay 10 bucks or so for it, but if it's only a SD projector forget it, he should be paying you to dispose of it. There's some cool optics in a CRT projection set though if you're into experimenting with that sort of thing. James, thanks for the opinion... That's what I needed. He indicated the repair shop offered him $50 for it. |
#5
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RCA P46720LV Bad Green CRT
On Aug 5, 6:43 pm, "Kirk S." wrote:
Found this set at a garage sale, owner indicated that he had service people come out and they told him the green "bulb" was bad. I'm taking this to mean the CRT is bad. Given that this set is probably ten years old and a replacement CRT is about $250, I didn't grab it for the $60 he wanted. What do these sets go for in working condition? I do like tinkering however that is a rather expensive tinker in my book. I don't have access to used parts either. Just wanting a few opinions... Would you buy it? Thanks, Kirk S. The "bulb" he was referring to would be the "green gun" All color CRT's have 3 guns, red, green, and blue. If the"bulb" is shorted, i.e. the cathode shorted to the heating element or possibly to the screen grid, it's possible to remove the short.You would have to have access to what is referred to as a CRT Tester/Rejuvenator. Sencore and B&K are still around. If the cathode or grids are open there's no hope. Either rebuild the tube or replace it. They are available for a lot less than $250. You'll never recover you costs for this, but if you like tinkering, enjoy. Have a good day! Mike |
#6
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RCA P46720LV Bad Green CRT
"Meat Plow" wrote in message
... On Mon, 06 Aug 2007 13:29:16 +0000, wrote: On Aug 5, 6:43 pm, "Kirk S." wrote: Found this set at a garage sale, owner indicated that he had service people come out and they told him the green "bulb" was bad. I'm taking this to mean the CRT is bad. Given that this set is probably ten years old and a replacement CRT is about $250, I didn't grab it for the $60 he wanted. What do these sets go for in working condition? I do like tinkering however that is a rather expensive tinker in my book. I don't have access to used parts either. Just wanting a few opinions... Would you buy it? Thanks, Kirk S. The "bulb" he was referring to would be the "green gun" All color CRT's have 3 guns, red, green, and blue. If the"bulb" is shorted, i.e. the cathode shorted to the heating element or possibly to the screen grid, it's possible to remove the short.You would have to have access to what is referred to as a CRT Tester/Rejuvenator. Sencore and B&K are still around. If the cathode or grids are open there's no hope. Either rebuild the tube or replace it. They are available for a lot less than $250. You'll never recover you costs for this, but if you like tinkering, enjoy. Have a good day! Mike Thanks for the information. Where would I obtain a replacement green CRT. This is a projection set that uses three separate CRTs... Kirk S. Do those work on projectors like the P46720LV ? |
#7
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RCA P46720LV Bad Green CRT
On 6 Aug, 12:44, "Kirk S." wrote:
"James Sweet" wrote in message news:hKuti.483$mw4.371@trndny09... wrote in message oups.com... On 5 Aug, 23:43, "Kirk S." wrote: come out and they told him the green "bulb" was bad. I'm taking this to mean the CRT is bad. Given that this set is Fix the existing crt. Every repair tech I know says its impossible but its not difficult. Please, elaborate on this if you would... Sure. I've done this many a time, so wont take much notice of the naysayers that always come along. The trick is very simple, boost heater voltage. Not by a measly 10%, thats semi-pointless, 33% V boost for mild cases, 66% for the worse ones. The simplest way to boost is to add an extra turn round the LOPTR core, just thread some pvc wire through it and hook up in series with the heater feed. If V drops, connect the turn the other way round to get boost. I once did an experiment, took a set with nothing visible on screen at all, solely due to dire emission, and hit it with IIRC +70& Vboost and +10% EHT boost. All guns came up, brightness was fine, but tracking of the 3 channels was a mess. Dont boost EHT unless you understand the issues involved, dont do it at home and dont do it on repair sets. Ah, there is one gotcha with this boost method: the tube must never have been touched by those dreaded cathode zapping rejuvenators. If you see a tube that smears, boosting it is a waste of time IME. NT |
#8
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RCA P46720LV Bad Green CRT
On 6 Aug, 22:53, "Kirk S." wrote:
Thanks for the information. Where would I obtain a replacement green CRT. This is a projection set that uses three separate CRTs... Kirk S. Not recommended. Gamma changes significantly over time, and a new tube working with old tubes makes for bad colour tracking. If you do replace a tube, putting an old one in from a scrapper would give a better picture. NT |
#9
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RCA P46720LV Bad Green CRT
wrote in message
oups.com... On 6 Aug, 22:53, "Kirk S." wrote: Thanks for the information. Where would I obtain a replacement green CRT. This is a projection set that uses three separate CRTs... Kirk S. Not recommended. Gamma changes significantly over time, and a new tube working with old tubes makes for bad colour tracking. If you do replace a tube, putting an old one in from a scrapper would give a better picture. Hence my dilemna... No spare parts... Thanks... Kirk S. NT |
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