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Discussion Starter · #1 ·
Last night I had a problem develop on my BD801s. Whilst I was watch it the blue suddenly began to get brighter. I switched off immediately, since I didn't want to risk damaging the blue tube.


Today I have cautiously switched back on, and the problem is still evident, but not as pronounced - well, certainly not for the short period I had the projector on for.


Looking closely at the effect, there are a number of points to note - all affecting the blue tube ONLY:


a) the colour seems to be unstable - slightly brightening, and dimming and some noticeable noise.


b) it seems to have lost focus


c) even when I select for green only or red only, there is still significant light output from the blue tube. If I select for blue only, there is NO discernable light output from the other 2 tubes


It's like there is always some gain being applied to the blue tube - even when there shouldn't be any output. This also effects the blanked areas around the picture, giving a slight blue halo to the display.


I've tried switching the blue and green RGB boards around (thought it might be a faulty 2SK511), but I still get the same affect.


Anyone got any bright ideas?


Thanks in advance,


Neil
 

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Quote:
Originally posted by kjaerligkatt
I've tried switching the blue and green RGB boards around (thought it might be a faulty 2SK511), but I still get the same affect.
Was going to suggest this but you've done your homework! Kudos! :)


I'd also say it points to the G2/Focus module (the one with the G2 and focus pots on it....). (That seemed pretty obvious I suppose!) :)


With the PJ off, try turning the blue focus and G2 pots back and forth to either extreme and then put them back to more or less the original location - the contacts may be slightly dirty.


The blue lead that goes to the focus block may also have a slight break in it somewhere. I had a similar problem where when I played with the cable (moved it slightly) the focus came and went as the cable had actually broken off the connector and only the rubber boot was holding the two close to each other.


If none of this helps, you may need to try a new G2/Focus module.


Kal
 

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I'd say that if the picture is getting brighter and dimmer, in and out of focus, and expanding and contracting you've lost regulated high voltage. I'd vote splitter, quadrupler, and EHT board as the suspects.


I don't recommend running long in this condition, but I think your 34 kVdc is dipping which won't necessarily cause the EHT to trip off since it primarily trips off on overvoltage. I would take a voltmeter and measure the sense line on the splitter with respect to chassis and it should be about 32-34 volts DC and if its dipping you'll see it swing below 30 volts.


I had a splitter go bad and it did this for a while before it zapped my EHT as well.


Mark
 

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Hi Mark,

I try to contact you but seem like your PM is not activated

I have an issue with my NEC PG9200 about G2 setting

Hope that beside Barco brand, you can mess around with my NEC ?

I'm in Grand Prairie

Please drop me an email to [email protected]

My PM is suspended by Alan :-(

Many thanks

Thuan
 

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Discussion Starter · #6 ·
Thanks Kal & Mark.


I suspect it might be to do with the G2 board as well, but don't have any idea of how to check it :-( Getting access to another module here in the UK to try swapping them around is pretty difficult, but I might be able to do so. I'll also try checking the cable and eliminating dirty pots.


As for losing the regulated high voltage, wouldn't this affect all three tubes, rather than just the blue?


Thanks again,


Neil
 

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Neil -


I hate to this, but your blue tube may have developed a short. Some, but not all, of the symptoms you describe are similar to those Mike and I had with our 801s blue tubes, and was very recently discussed in this thread:

http://www.avsforum.com/avs-vb/showt...hreadid=293753


More information is this thread:

http://www.avsforum.com/avs-vb/showt...hreadid=291445


Really hope I'm wrong and that you eventually find a relatively simple problem with a board or just a wire somewhere...but I think it's fairly possible your blue may have gone bad.


- Chris
 

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Discussion Starter · #8 ·
Thanks for the info Chris. It might not be such a bad thing for me if it is the blue tube - it needs replacing anyway.


The problem isn't evident all of the time (yet), so it may be a component in the process of failing. Or maybe an intermintent short. I'm going to check over all the connectors, and have a look for any obvious dry joints on the G2 board.


Having suffered from spot burn recently (due to solder joints on the PSU transformer), I want to make sure everything is 100% ok elsewhere before replacing the blue tube.


Is there an easy way for me to eliminate the G2 board as the problem e.g. is it easy to swap over the signal feeds into the individual tubes? This is a ceiling mount, so delving into the projector too deeply can be akward. I was thinking of making a little extender cable for the feed into the RGB board, and taking the feed from the green tube and plugging it into the blue RGB board.


Neil
 

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Neil,


I guess I missed that it was the blue tube only. Certainly check the focus module out. I routinely see a couple of bad solder joints on that board where the large resistors are installed.


Mark
 
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