AVS Forum banner

Status
Not open for further replies.
1 - 10 of 10 Posts

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #1 ·
Hi all! I have been immensely enjoying this forum. Because of budget constraints, I am contemplating a worn/burnt set that i can 'fix up'. I found this explanation of marquee tube replacement/alignment and am wondering if this applies generically to all crt, or just that model? If it is not generic, does anyone recall a thread that describes the process for a NEC PG model?


from this thread

Quote:
VDC would have you strip the various yokes (magnetics) off each tube before sending them in; correct realignment is a bit of work. The front yoke is sweep and must be set for level horizon, I start with green and match the other tubes to green; then set those with hot melt glue. The convergence yoke is next and must be set so that zone correction is proper vertical and horizontal; this yoke is then clamped to the tube neck and glued to the scan yoke in front of it. Next in line is the focus yoke; it also acts something like a centering magnet, the focus yoke is aligned together with the flare magnet rings (rearmost yoke) to give a concentric flared dot shape AND a centered raster with no static correction applied. These alignments are better done with the tube covers off; the tubes are lifted up and the covers go on last. Whew! And this is part of why a skilled retubing job takes most of two days. Those reluctant to undertake all of this, which involves reaching amid lethal voltages in a running projector chassis, can send Marquee tubes or the entire projector here for strip-down and reassembly. Also, sweep yokes come hot-glued to the original tubes and can be damaged if not removed carefully.
I saw several posts where people describe putting this electronics back on the tube 'as close as possible to the original tube.' Is that adequate or is this the necessary process?


Ideally I find a set that is toasty but watchable so I can learn about crt some before needing to embark on this. A brown tube is going to look so much better than my 31" rca tv that I think I'll muddle through until new tubes :~) Anyway, I've worked on crt monitors some in the past in a limited sense, and have a decent technical background, so I'm just wondering how insane I am to contemplate this?


Thanks for any help here!
 

·
Registered
Joined
·
18,503 Posts
Email me a fax number to:

[email protected] and I can send you the tube replacement instructions. They're really tricky though, as you have to translate NEC's "English" into real English, then try and figure out what they're saying..:(


Curt
 

·
Registered
Joined
·
3,480 Posts
I guess that is one way to enter the CRT world cheaply. Get a burnt PJ that nobody wants and put new tubes in it as you can afford them. You end up with a new PJ, not a bad way to go.


I retubed a couple of PJ's and it was not very hard. I'm thinking ot doing the same thing with a Sony 1272 or a Barco 8XX as I have new tubes just collecting dust.


Good luck.


Deron.
 

·
Registered
Joined
·
3,901 Posts
I recently learned through my own ignorance that setting up the tube neck electronics on an NEC are quite simple if you do them one at at time and take your time. I replaced the blue tube in an NEC 6PG and thought I was centering the raster with the centering magnets, when I was done, hte grid lines looked too thick and indistict. Well, silly me, I had been twiddling the astig/flare magnets ! Well, needless to say I had to go back to square one. I set up the astig so the core was in the center of the underfocussed dot, then I went to over focus and rounded out the flare(nice fat round halos) then I went back and forth from under to over focus to check that I had it centered and the dots didn't move during focus. Then I set focus to zero, and loosened the focus coil and moved it back and forth and turned it side to side, till I had the dots perfectly focussed on the crt face with the focus control set to zero.Then I set the skew to 0 and checked the horizon and tweaked the front yoke to level the horizon, THEN I finally went back to the centering rings, I had found in a different place than I expected them. NOW I centered the raster, then set the phase, then centered the image. Now the newly installed tube looks great and really sharp.

One should still do color balance and I would think g2 setup, which is really quite difficult on an NEC'a apparently, but I just pushed the Kelvin button on the remote and the color looks good to me, but then, I'm NO TECH.

PS: The physical task of changing tubes in NEC PG an XG's is really easy.
 

·
Registered
Joined
·
1,038 Posts
Thanks for the information on tube replacement Paul. Newbies like me and others on this forum really appreciate the contributions people like you make to this forum. :D


A question for you. Is the convergence yoke glued to the tube? If so, what is the best/safest way to remove everything off the old tube and replace on the new one without doing any damage?


Thanks,

Brad
 

·
Registered
Joined
·
3,901 Posts
I've never encountered a yoke glued onto a PG tube, but there's always a first time. They stick when you try to take them off but only because they have been heated up and cooled many times while attatched, and there's a piece of fabric tape between the magnetics and the tube neck that gives it a little stick. Tubes are breakable, they are glass after all, BUT they are tough enough to be vacuum sealed at quite a high pressure, so they won't break (generally, but anything could happen, a guy near me was killed in a car accident while watching tv in his living room!) by pulling the magnetics off. Make sure the fixing screws are loosened, then just twist the magnetics a little to break them free, then just pull them off. Be more concerned about bending/breaking the pins on the end or pulling the cap out of the HV lead. These are far, far more likely to happen as opposed to breaking the tube. When you pull the boot off the HV splitter, make sure you work the boot up the connector, don't just pull it off or you'll pull the cap out of the end of the HV lead for sure, and you don't want the cap stuck in the splitter.

PS: Where in Canada? Are you close?
 

·
Registered
Joined
·
1,038 Posts
Hey Paul,


Thanks again for the tips. I'm from Edmonton, AB. I spoke with you on the phone when I first got my projector in a couple of months ago and you helped me out a lot at that time. I bought a new green tube for my PG9200 and I am trying to find out any and all information I can in regards to tube replacement procedure and the calibration that follows before I go ahead and tackle it. (I've never done it before!) I guess I should really get my hands on a service manual in regards to G2 and various pot settings. (There are a lot of pots and I only know what a couple of them do.) I am familiar with astig adjustments made with the CPC magnets as Doug Baisey was kind enough to email me a page regarding the 2, 4 and 6 pole magnets and taking dimensions between the magnetics and the coil before transfering them to the new tube so I think I'll be able to handle that part of it. Raster centering is not a problem either as you were kind enough to email me a couple of pages regarding that matter....Are there any other tips that you could give me or do you have a spare service manual kicking around? I just don't want to go yanking out the old tube and find out I missed disconnecting something or another or did something wrong...


Thanks,

Brad.


Oh by the way, are shooting par by now? :D
 

·
Registered
Joined
·
3,901 Posts
Brad, The rain only stops on days I work, so I haven't been able to improve on my game too much! I just got back a photocopy of the PG 6200/9200 service manual, email me if you want a copy.
 

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #9 ·
Gentlemen, you rock! I have rushed in to many things (mostly succesfully) where I realized in the thick of it that it was more than I could handle. This sounds do-able! I don't want to end up paying shipping on an expensive paperweight times three trips (i.e. I fudge the tubes, ship it to an expert, ship it back - that won't help me afford it... )


Off topic - I went to a local satellite/theater store and they were kind enough to talk about the used pjs they had - an ancient zenith video only and a GIANT jbl 6xxx. In all earnest the fellow looked at me and said "what do you want this for? I havent sold one in 12 years..." I briefly explained that I was after better picture than fixed-pixel, and cheaper. He then offered to sell me a refurb'd 1996 model lcd projector for the bargain price of $3995. Oh well. Nice to be among fellow nuts who understand these things :~)


Anyway, thanks alot!
 
1 - 10 of 10 Posts
Status
Not open for further replies.
Top