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Discussion Starter · #1 ·
Guys, I got in two tubes from VDC this week: 180DVB22B and 180DVB22G. I just finished pulling the duds from my BD808, and got the magnetics transferred onto the new blue. I started doing the green, and noticed the green tube from VDC is missing the clear plastic tubing normally wrapped around the HV lead.


The blue tube from VDC has this tubing, and all the original Barco tubes have them, but the green, hmm. My guess is this tubing is normally used to protect the HV lead's insulation from getting beat up within the chassis, and that I should go find some clear tubing and slide it on. But the HV cap is already on the lead, so I'm not sure how I'd get the tubing on OVER the cap.


My new green also has a pretty clear texture to it. I can't tell if the texture is the glass on front, or if it is the tube surface/phosphor itself that has this texture to it. I'm hoping that I shouldn't have to worry about this, but if so, its going back to VDC.


The green also looks like someone got a gob of gum or silicon on the side of the tube, and rather than trying to take it off, they stuck a small strip of scotch tape over it. :) The more I think about this, I might want to return this tube right back to VDC and ask for another. :)


Second question: VDC sent the tubes with a ground lead already attached. The Barco tubes don't use a ground lead, the bottom plate that holds the tube to its frame contains a ground lead. Which lead do I use to ground the tube, as there is only one ground connector available on the neck card (the other is used to ground the magnetics).


Thanks folks!
 

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The green tubes seem to be the ones that have the most problems in the rebuild process. I would not be to hasty to return until you check the tube while in operation. If you see small holes in the phosphor and black specs then you have a problem. The best way to check this is on a all white screen with all three tubes running. Look for specs of orange on the screen.If you see that, then a closer look at the tube is in order.In the long run with VDC tubes even with a few flaws you will never notice them in the video.
 

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I'm with matrix, some of the tubes have the tubing, some do not. I've never had any problems either way. Cut the ground lead off and use the original, otherwise I usually coil the ground lead up and wire tie it, can't have too many grounds you know..:)


Curt
 

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My 180DVBs from VDC were similiar to what you describe. Except my blue had more texture than my green. In fact my green looked just like the original . My blue was also missing the clear tube over the HV lead.


miles
 

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Discussion Starter · #6 ·
Kind of annoyed me about them missing the tubing. Oh well.


I finished mounting the tubes tonight, and the machine fires up normally. There's a clicking sound that I'm not sure is new or not, but otherwise all three tubes produce a picture, and my G2 is horribly off.


I don't have time to do the alignment work tonight. I'll start that on Tuesday I hope, and finish by sometime next weekend. So I still have the hard part left. :)
 

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spearce,


Yes, dialing in the tubes makes the actual installation look like child's play. In particular adjusting that astigmatism will drive you bonkers. If you don't already have a pair of binoculars buy/borrow some. It is too much to try to keep running to the screen. My blue tube when adjusted, the settings were pretty close to the original. The green was not and took much longer to get right. You start to go cross eyed after a while. I would say that I spent several hour per tube on the adjustment including the electronic astigmatism adjustments. I took my time and would stop when I got tired....


Miles
 

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Spearce, The clicking noise worries me. Make sure this is not high voltage arcing from the red lead to ground. I would give Charlie a call about the missing insulation. I am sure he could and would send you a piece in the mail.
 

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Discussion Starter · #9 ·
matrix, the chassis was completely open. I think I would have seen the HV arcing to ground, but I'll look again on Tuesday. Perhaps the arch is very, very short, so not really visible.


If it is the HV leaking out, that clear plastic tubing won't shut the leak. That plastic tubing only protects the HV insulation to keep it from getting damaged, and letting the HV leak out. If I have an HV leak, I'll have two options: try to seal it with silicon (gobs of it too), and then put the plastic around the lead to prevent further damage, or send the tube back to VDC for a replacement lead.


I've got a pair of those short focus binoculars we love for CRT adjustment, so all set there. But yea, I'll go bonkers doing the setup.
 

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Spearce,

the only benefit that I've noticed from the clear plastic tubing, is that the projectors that have it has less snap-crackle-and-pop on start up, than the sets that does not have the tubing. Some say it helps isolate the high voltage from touching anything in the projector. I disagree with this, I think if that high voltage cable wanted to arch, it would. And it wouldn't be because it needed help (isolation), it'll be because it needs replacement. Other than that minor snap-crackle-and-pop on start up, they're otherwise a useless addition (just my opinion on this).


The clicking that you're hearing sounds more like the tubes breaking-in. During the break-in process, it's not unusual to hear a snap or click from time to time. During the rebuild process (and even with brand new tubes), small particles can get into the tubes sealed envelope. During the initial use of the tubes new life, these particles will start to ignite inside the tube. This is a normal process (self cleaning), and can be more of a problem on some tubes rather than others. This burn-in or break-in process will usually expire after 20 to 50 hours of the set being in use, but in some cases can last over a couple hundred hours.


The break-in period is the most determining period of the tubes life. It is the period that will determine if the tube will live or die (yep, some fail during this period). It's also the best time to determine if you should send the tube back. During this period, it'll be good to decide if you'd want to live with any of the abnormalities, though some are normal. But no particular tube should be that much different from the other two. But do be more concerned with how well the phosphors break-in (impurities on the phosphor - blotches, etc). If you can, do a quick eye color balance, and from there keep your eye open for a drift or chnage in any of the three tubes intensity over the break-in period.
 

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Discussion Starter · #11 ·
Thanks Mike. When I first heard the clicking, my guess was that it was the tube breaking in, as you mentioned. I've read that its totally normal. I didn't suspect HV leak until someone else suggested it, as this click seems to have an irregular cycle to it. If it was the HV leaking, I'd suspect it would have a much more regular cycle, and most likely be occuring at a much higher frequency then the clicking I am hearing.


I guess then I'll fire the machine up on Tuesday and run it while doing some quick and dirty astig/em focus, etc. and try to put some time on the tubes.


Should I then wait to send my duds back until I've gotten a few hundred hours on these tubes? If I send the duds back to VDC now I'll have to wait for VDC to ship me empty packing material to return a failed tube (if I happen to be so lucky to have one). Or is VDC generally good about that in that they'll send me the new one, and I'll ship back the "new dud"? :)
 

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Discussion Starter · #12 ·
I've finally got time to work on the actual astig on these tubes, and just noticed that the "clicking" I was referring to isn't there anymore. Chalk that up to impurities in the tube burning off on the first 20 minutes of runtime.


What I am hearing is a _very_ fast clicking sound, more a buzzing sound, around the center of the green tube, or so it seems to be located. Might be the HV splitter, or nearer to the bell of the green tube. At first I thought it sounded like a clicking from something stuck in a fan and the blades wipping around, but when I put my ear to the running fans not one seems to be responsible for the sound. So I'm suspecting that I do in fact have a leak on the green or at the HV splitter.


The pitch of this buzzing changes based on the video signal being sent. After about 20 minutes of runtime the buzzing seems to not be as loud to me, and I think that if I put the tube cage lid back on I wouldn't even hear it. I want to say I think this is normal and that I remember the unit doing this even with the old tubes, but I don't think it really did...


Suggestions?
 

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Kill all the lights and see if you can see blue corona anywhere indicating HV leaking.


I had an AmPro 20000 a while back that had intermittent arcing and I could not find it. I turned out the lights and it turned out the leak was right at the HV supply where the HV lead went in with the twist lock bayonet connection. A new HV lead spliced onto the old one solved the problem.


I doubt that's the case here, VDC replaces all HV leads.


Curt
 

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Quote:
Originally posted by spearce



and I think that if I put the tube cage lid back on I wouldn't even hear it.


Suggestions?
That's the best suggestion so far. But before you do that, fire-up the projector with a rapidly changing signal (bright scenes). Cover the lenses and then turn off the lights with the cover removed, and in a totally dark room look for arching, and while looking into the projector, raise and lower the contrast.


If the arching is seen at the base of the green tube that's normal, and may or may not go away in time. But if the arching is around the tripler or coming from a certain spot on any of the high voltage leads, you should be concerned. Because high voltage breakdown can damage sensitive silicon devices on PC boards. If the arching is random along the HV leads, that's also normal, it's more of a static rather than an arc.


This problem could still be "break-in", therefore, I would leave the projector in the standby/on mode for the hundred hour break-in period, rather than turning it off.
 

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Discussion Starter · #15 ·
Ok, thanks Curt, Mike. I'll have to look at it more this weekend.


How the hell do you guys get 100 hours on a CRT? I'm working 18 hours a day during the week, leaving me (tired) and with little time/energy on the weekends. I don't want to run the CRT when I'm not home, at least during its 100 hour break in period in case something DOES go wrong. :)


I've been looking at the machine with the lights out (TOTAL light control, with the lights off I can barely see the internal wired remote to turn the machine on) and have not seen anything except the normal coronas from the tubes, but I'll try some of your excellent comments as well in a few days and see what I learn.


Thanks!
 

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spearce,


One word of advice, my green VDC 180DVB for my Barco 1208 developed two phosphor "dead" spots (similar to dead pixels in a digital) after about 15 or 20 hours of use. Note this was not due to spot kill failure or some such. They definitely were not there when I first installed the tube but came up later after some use (even though I was running at reduced brightness and contrast as suggested here). Luckily I had not mounted the projector yet, though I had finally put everything together in the projector, ugh..... So take your time testing the tubes and running them in before mounting the projector, etc.... My blue tube BTW is great no problem there and dialed in great.


secstate
 

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Discussion Starter · #17 ·
secstate - thanks for the heads up. Fortunately its a floor/table mount, so its always mounted for both display and as a workbench. :D
 

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I've got mixed feelings about the clear plastic tubing. I have an Ampro where the red crt HV lead turned into a spark plug wire. There was a pin hole blasted throught the insulation where the wire enter the rubber cap on the crt bell. Unfortunately the path to ground that it ultimately found was through the deflection yoke and about three electronic boards.


I think that had the tubing not been there, it might have sought out an earlier path to the chassis at a point further up on the cable which wouldn't have been so bad.


The Spellman HV power supplies are current limited, so the arc isn't so bad on them. Repeated arcing can cause them to over heat, however. Like Curt said, I also had a projector that formed a corona around a splitter box port. I could tell something was wrong because the basement smelled funny from all the ozone. It was darned scary to watch.


Ray
 

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Discussion Starter · #19 ·
Just to follow up on this...


I got time to play with it today, and looks like I don't have an HV leak. Though I do have a buzzing which comes from either the green convergance yoke or the Spellman HV splitter. You guys think this is normal? I think this may be how the machine was before I swapped the tubes. With the tube cage closed I can't hear the buzzing, but it is pretty audible with it open and standing about 1 foot from the tube cage.


Looks like its time to do the astig and EM focus steps after tube replacement. :)
 

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Spearce, Sounds like you may have a buzzing yoke on that green tube.


This would vary with screen content and load. It is possible upset the laminations when changing yoke from one tube to another. It can be normally fixed if this is indeed the problem by soaking the yoke or painting the yoke with some clear lacquer to bond the windings together again.


Steve


And hey, not being so 'lazy' at the moment!
 
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