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jarseneau
Joined: 06 Nov 2007
Posts: 323
Location: WI
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| Posted: Fri Dec 26, 2014 8:09 pm Post subject: Because a CRT tube is a terrible thing to waste... |
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Well, I learned this past week how to spot burn a G90 CRT after remounting the projector and re-installing the tubes. It turns out that I bent one of the neck pins when sliding the CRT assembly into place and didn't notice it. When I powered up the RED was overdriven for a second or 2 and then collapsed with an error code. The bent pin was not connected in the CRT neckboard socket and that allowed the beam to go full strength. After thinking about how this happened I realized I must snagged the pin on a hanging wire and I didn't see it because it was on the underside of the neck.
So my strong advice to anyone mounting a CRT with the projector on the ceiling is to put the dummy socket on the neck that comes when you buy a CRT or just put duct tape on the pins if you don't have one. That will remove the potential for those tricky pins from finding the first loose wire to team up with.
At least the tube had about 13k hours on it but it was still working fine with no wear showing.
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Jerry
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HK-Steve
Joined: 15 Jul 2006
Posts: 849
Location: Switzerland
TV/Projector: Marquee 9500, Epson 8100
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| Posted: Fri Dec 26, 2014 8:39 pm Post subject: |
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ouch,,,,............
Hope you have a replacement
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redfox001
Joined: 16 Mar 2009
Posts: 2257
Location: The Netherlands
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| Posted: Fri Dec 26, 2014 9:14 pm Post subject: |
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I believe that when you don't switch the set off the HV will shut down and if you shut it down after that you will not get spot burn. The brightness might be caused by the g2 pin not being connected?
You can also pull the blackwire connector.
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701s->runco933->8500ultra->cinemax->9500mp->919 splitpack + cinemax
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jarseneau
Joined: 06 Nov 2007
Posts: 323
Location: WI
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| Posted: Fri Dec 26, 2014 9:31 pm Post subject: |
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 I'm betting it was the G2 pin, too.
It would have been great if I had the reflexes to react in time but at least on this projector I don't think I would have been able to pull anything in time (before the pj shut itself down) even if I knew it was about to happen and I was certain which wire to pull. The whole event took 3 seconds.
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Jerry
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Sat Dec 27, 2014 1:52 am Post subject: |
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If you should ever run a Marquee with G2 disconnected, the only way to avoid a spot burn on shutdown is to pull the P14 filament voltage plug which can be reached under the blue tube assembly. Once the image has disappeared, THEN shut down the projector. For safety's sake I attached a pull cord to that plug so I can kill filament voltage easily, quickly, and safely if need be. This HAS saved tubes for me. I run the version of tubes that have bias on pin 6, not 2, and it's easy to miss the pin when trying to connect the G2 lead.
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