CurtPalme.com Home Theater Forum

[Elaine Benes]

This problem is the focus board, I'm just about certain of it. I have a projector here that does pretty much the exact same thing, and the electronic adjustment has no effect, it can't be anything BUT the focus board under those conditions...Question now is, which of the big STK's on the bottom of the focus board controls edge focus, and which controls center focus ?

[Elaine Benes]

Just wanted to confirm, I swapped the focus board between my two 852's, one with a nice Windows2000 logo burned dead center into the green tube, and one which wouldn't focus on the sides, and the focus issue went away.

The bad focus board has two spots on the back that appear burned, I'm no tech, board swapping is the extent of my expertise, but I'd lay money the components where the burned look are were to blame for the loss of side focus capabilities. All fixed now that the F-Drive is swapped out, btw.

And I must say, the NEC's are a bitch of screws to remove to change out the boards, but kinda neat to have the back card cage elevated and work through that opening. I was a bit surprised that I had to remove 200 screws and lift that back card cage, AND remove the green neck board, JUST to change out the F-Drive... I'm glad though that it worked.

Satanier, I'd lay money, having seen your screen shots and read your descriptions, that a new(to you) F-Drive would fix up your issues...

[Satanier]

[Elaine Benes]

[Satanier]

[Elaine Benes]

There's only one F-Drive in your projector, ie. only one "focus board"....I'm not sure what you mean when you say "Wouldn't swapping the cables from another focus board have revealed it as the problem though?"

[Satanier]

[Elaine Benes]

All I can say is "if I were you", I'd try a different F-Drive, regardless of any previous attempts at eliminating different causes, but if you don't want to, that's fine too.

There are a limited number of causes for your issue, and the *most likely* culprit will be your F-Drive, I'm sure that *usually* doing some swapping of control cables might be enough to eliminate that as the source of your issues, but I'm not right there watching what you're doing so I can't say with any degree of certainty if what you've already attempted has been implemented properly, so I'll stick with my assertion that "if I were you" I'd pop in a known good F-Drive as the first thing I'd try...

[Satanier]

[Elaine Benes]

Considering the market for used crt's in general....*I* wouldn't likely pay more than about $20. for a board, but I'm a cheap bastard who doesn't mind waiting till he finds something in his price range, you may be a different sort who values things differently....

Here is the largest concentration of enthusiasts left, sad to say...search the Buy/Sell forum for NEC and start PM'ing people. Depending on where you are in the world, there may be someone right down the street with the part you're looking for. You could, of course, ask Curt too(not to be too obvious...).

[MrGogo]

Hi Elaine, Satanier,

I had this same issue and it was my F-Driver. I swapped the Astig lead and Focus lead to the green tube with the blue and ran it that way for a couple years before some other parts blew and I got them all repaired by Curt. It was a paint to have to focus the blue and the green controls and vise versa but it did work and save me the $ for an immediate repair. As has been said many times in this thread before. If swapping the Asting and Focus leads between the blue and green doesn't move the problem. Given your claimed perfect blue focus then its not the F-Driver. (In my opinion, without actually looking at it first hand we're all guessing here right guys)

Despite Elaine's claim that he is positive that its your F-Driver all the guys on the forum here who have helped you pretty much eliminate that possibility. I've read this thread from start to finish and given what I've read I would suspect its either a bad Green Tube or you have bad coils (or badly positioned) coils on your green tube.

You don't really have much to loose at this point, you've stated you can't afford a new tube. So you've eliminated the electronics and you can't afford a new tube, whats left the coils! So try swapping all the coils on the Blue and Green tubes. Take pictures and make sure to mark where everything goes. If the focus problem follows to the blue tube then you've just narrowed it down to bad coils, which if I'm not mistaken are relatively cheap parts compared to say a new F-Driver (200$ ??) or a new tube (600$ ??). You might even be able to to it without actually taking the tubes out of the projector, I can't remember how much room is in there, if that is something that you are not comfortable doing.

Just my 2 cents.

Good luck,

Brian

[Satanier]

Here I am 4 years later, and I'm ready to take the PJ out of storage and take yet another crack at this. I'll probably be ripping my hair out shortly.

Does anyone have any fresh ideas? I now have a digital multimeter and oscilloscope, and a bit more electronics knowledge. It's been suggested that I put in a new F-Drive, but I had tried swapping the cables between tubes with no luck in the past. I know some have suggested swapping tube locations, but this really does seem like something I'd like to avoid unless I'm sure it's necessary. If I do swap them and find out the green tube is bad, I can't justify the cost to replace it, so then I would just have to reassemble and still have the same issue. I may take another look at the magnetic astigmatism adjustment, because there were conflicting viewpoints earlier in the thread about whether or not that could be the issue.

Thanks for any help.

[CasetheCorvetteman]

Swap the focus yokes and astig rings between red and green.

If you do that, youll have to redo the astig anyway. Reset the electronic astig to all zero, then swap the focus yolk from the red, and also the astig rings from the red. My 9PG had some astig magnets that went bad enough that i couldnt get good focus on that. Swapped them out with some spares and its perfectly good now.

[Satanier]

5 Years have passed and the XG still has the green tube focus issue. I've been using the projector on and off since my original post and set it up again last night. The picture in this post: http://www.curtpalme.com/forum/viewtopic.php?p=166394#166394 shows the issue fairly well. It seems to be blurrier on one side when I look at it now. The problem is visible on the tube face itself. Is there anything else I can try that doesn't involve disassembling the PJ? I'd like to know what is causing this issue after all these years. The image from this unit is still so impressive but I'm frustrated by this problem preventing me from achieving a perfect setup. Curt suggested earlier that the focus board could be the problem. If that's the case for sure I should probably just order a new one and swap it out to test, assuming that's not too difficult or expensive.

[Curt Palme]

Ok, I'm first to admit that I haven't read the whole thread, but I'll add a few things I'm gonna guess that aren't covered, or at least I'll sum up.

1) if you see the issue on the tube face, it's definitely an electronics issue, not optical.
2) Set all astig and focusing settings to 0. Don't unplug the leads going to the tube to disable the focus or astig, I believe a resistor smokes on the A or F board when you do. It's been a while, I can't remember, but don;t chance it.
3) Since the image appears to be blurrier on one side than the other, and as long as you can see that on the tube face as well, we can rule out a bad astig or focusing board (at least from all the failures that I've seen). A bad focus board usually will defocus the left and right sides massively, I've never had a bad astig board, so I can't tell you what that looks like.
4) My guess is that the mechanical astig is off to start. That's why I'm having you reset the focus and astig settings to 0. Once you do, use the trimpot in the card cage to run through focusing, from bad to good, and then bad again on the other side of it being set correctly. Turn the contrast to 100 when you do this, as that drives the tube harder, and use the dot pattern rather than the H focus pattern.
The big question is, are the dots round all over the screen, and do they defocus into blurry dots, or do they go to ovals or lines? Do you get triangle shaped dots anywhere?

Start with that, and answer the above questions if you would.

[Curt Palme]

Ok, I'm first to admit that I haven't read the whole thread, but I'll add a few things I'm gonna guess that aren't covered, or at least I'll sum up.

1) if you see the issue on the tube face, it's definitely an electronics issue, not optical.
2) Set all astig and focusing settings to 0. Don't unplug the leads going to the tube to disable the focus or astig, I believe a resistor smokes on the A or F board when you do. It's been a while, I can't remember, but don;t chance it.
3) Since the image appears to be blurrier on one side than the other, and as long as you can see that on the tube face as well, we can rule out a bad astig or focusing board (at least from all the failures that I've seen). A bad focus board usually will defocus the left and right sides massively, I've never had a bad astig board, so I can't tell you what that looks like.
4) My guess is that the mechanical astig is off to start. That's why I'm having you reset the focus and astig settings to 0. Once you do, use the trimpot in the card cage to run through focusing, from bad to good, and then bad again on the other side of it being set correctly. Turn the contrast to 100 when you do this, as that drives the tube harder, and use the dot pattern rather than the H focus pattern.
The big question is, are the dots round all over the screen, and do they defocus into blurry dots, or do they go to ovals or lines? Do you get triangle shaped dots anywhere?

Start with that, and answer the above questions if you would.

[Elaine Benes]

and you've never replaced the entire focus board, right ??

I'm almost certain I've seen exactly what you describe in a machine I had here years ago, replaced the focus module and viola, fixed...

If you haven't replaced the entire focus board(located between the tubes, if I remember) yet, you can't even start to figure this out...I'd say its the first thing to do...but that's just me, you can keep going for another 6 years too if you like...

[CasetheCorvetteman]

Hahaha!!