CurtPalme.com Home Theater Forum

[CasetheCorvetteman]

Hi everyone, i had this issue a while ago with the green tube on my NEC 9PG, seems the focus is sharp in the middle, but it seems to be flared abit at the corners, mostly so in the bottom left corner.

I notice this most when i have a 240p 60Hz signal going in RGB-S, the text at the bottom left has a noticable green flare coming off it like as if the astig is way out.

I know the astig is not way out though, cause i replaced the astig rings on this tube and redid the astig, which made things alot better at the time, but now its coming back again.

If the screen is full white, with black around the text at the bottom, the flare isnt there, and the green is sharp all over the screen. So certainly not the astig. If the screen is showing pictures, the issue is worse with there is alot of brightness, but is almost gone with full white screen.

I dont know if this is happening with blurays at 1080i, cause i havent seen it, the picture is very sharp.

I do have a fair few spare boards here, including a focus board, convergence board, and a few others. What board would be responsible for this issue?

Thanks in advance.

[gjaky]

Hello,

If you watch directly to the lens the picture is sharp on the tube? Maybe your scheimplfug rings are not properly set. Or try to swap the red and green focus plugs, and watch if the flaring goes on the red?

[CasetheCorvetteman]

No mate, wont be lens flapping. The 9PG doesnt have scheimpflug, and this is not a mechanical focus issue, this is electrical. It has plastic rings with a size marked on them, and although i have only got the 200" size rings and im using a 120 inch 4:3 screen, this is not the cause of a somewhat dynamic flare that only occurs on green. ( if anyone knows what the correct thickness the 100 or what ever is closest rings are, id love to know that for future reference )

When i have a full white screen, the green focus is sharp across the whole screen, and can clearly be seen as sharp, by any text that has a black border around it.

If there is a large white area on the screen, the corner focus is sharp.

If there is any other sort of image, which is obviously most of the time, the green focus is flared towards the right, more so in the corners, and more so the bottom left.

If i put up the dot patern, the center dots are perfectly good, the outers are pretty ordinary, and the lower left dots are like an oval with a br coming out of it, flared towards the upper right. Adjusting the focus ( either the pots or the menu controls ) do little to change this.

When you say to swap the focus plugs, which plugs are you talking about swaping? The ones for the focus yokes?

[gjaky]

[CasetheCorvetteman]

Yep, i know the ones, ill give that a go at some point. I was wondering which ones you were talking about to start with til i went and had a look at one of the spare focus boards i have here we got from you a while ago.

I havent ever had a focus board out of this machine so i dont know how hard itll be to do on the ceiling, but if its not too hard i might go over one of the spares and throw it in, ive always felt the focus on this unit is not as good as i got it on my mate's 9PG...

[CasetheCorvetteman]

Seems both boards have a problem with the edge focus on the green, is this a common problem??

If i swap to the red, i can focus the green with it perfectly well. Both boards seem to have this same issue, although one board the green edge focus is even worse.

What parts on this board are related to edge focus??

[gjaky]

The "dynamic focus" is controlled by IC8001, IC8004, you can try to swap the STK392-040...

[CasetheCorvetteman]

Do they go bad and yet still work abit?

[gjaky]

just two days ago I repaired a sony RPTV, it had some convergence distortion only on green in the up right corner, and it was the STK -exactly the same: STK392-040 there too

[CasetheCorvetteman]

hmmm, so they get weak towards the end of their life?? The focus board had 5 leaking caps on it, after replacing those and putting it back in, it is abit better, but green is still not spot on.

Doesnt matter what i do with the astig rings, i cant get the edges good, and the corners are sh*t house regardless of what i do, and always have been. When its all dialed in though the picture looks exceptionally good.

[Curt Palme]

gjaky's experience is a bit unique. With all the NECs I've repaired, the focus adjustments either work or they don't. NO inbetween.

Look into the lenses and see if the image is out of focus on the tube face. IF so, it's an electronic or astig issue. If it's clear, then it's a Scheimpflug issue.

Normally when the STK goes, you lose focus massively on the sides with zero adjustability.

[Curt Palme]

gjaky's experience is a bit unique. With all the NECs I've repaired, the focus adjustments either work or they don't. NO inbetween.

Look into the lenses and see if the image is out of focus on the tube face. IF so, it's an electronic or astig issue. If it's clear, then it's a Scheimpflug issue.

Normally when the STK goes, you lose focus massively on the sides with zero adjustability.

[CasetheCorvetteman]

Thanks Curt, i spoke all about this allready in the first and 3rd posts, its obviously electrical, and not lens flapping.

Its not clear on the tube face, it is however perfectly sharp on the whole screen when a certain amount of white is in the image. I can tell it is cause the text on some of my arcade games that say "CREDIT" in the lower corners is where i notice this out of focus issue, and when the screen goes white, the word credit has a black edge around it so it is still visible over the white, and it is sharp as a tak. It is also far less noticed on 1920x1080i.

That to me says without any question that we are looking at some sort of electrical issue, but what? Which board could contribute to this? The focus is now working on the edges, but not very well.

Does not matter what i do with the astig rings, i cant get the edges any good at all. Can spend hours on it and get nowhere. Yet with the Sony, 5 minutes and all 3 tubes had perfect astig and it was so easy!! This 9PG is the only projector ive never been able to get the astig set nicely on.

What can be adjusted or moved to cause the edges and corners to have better astig that is more like what is seen in the center of the screen?? At the moment when it is defocused the corners are pathetic.

[barclay66]

[Curt Palme]

Well, the signal driving the focus board comes from the CPU boards, system, wave, etc. IF you've got spares, swap those out. I can't see two focus boards having the same issue.

I thought that your flare could also be due to the video signal you're feeding it. It doesn't make a lot of sense that on some images the focus is fine and on others it flares, but too strong of a video input will result in video clipping, which can also flare off the edge of an image or distinct line on the screen.

[Curt Palme]

Well, the signal driving the focus board comes from the CPU boards, system, wave, etc. IF you've got spares, swap those out. I can't see two focus boards having the same issue.

I thought that your flare could also be due to the video signal you're feeding it. It doesn't make a lot of sense that on some images the focus is fine and on others it flares, but too strong of a video input will result in video clipping, which can also flare off the edge of an image or distinct line on the screen.

[CasetheCorvetteman]

Thanks Curt yeah, i dont think that is the issue either, cause it does it with all of the 240p RGB-S signals i feed it, probably does it on 1080i as well, i just cant see it cause it doesnt have such big jail bar scan lines as 240p does.

I do have another of each of those, ive allready tried system boards and that made no difference, so i might give the wave board a go.

Thanks Barclay66, although the others did test perfectly good.

[AVphile]

Same problem with my green here on BG808s (SONY 07MFP2 tube). The bottom right corner (on the screen with PJ ceiling mounted) is always a bit off no matter what I do with the lens or astig.

Right now I'm trying to figure out which magnetic focus yoke it has to make sure the jumper on the convergence tray is set correctly.

[Curt Palme]

Look into the lens with sunglasses. THat sounds like a Scheimpflug issue, not an electronic one. It's optical focusing. If the tube image is clear on the tube face in that corner, it's not electronics.

[Curt Palme]

Look into the lens with sunglasses. THat sounds like a Scheimpflug issue, not an electronic one. It's optical focusing. If the tube image is clear on the tube face in that corner, it's not electronics.

[hansilili]

Why don't you check optical focus (Scheimpflug) with phosphorous grain on a full white picture?

hansilili

[CasetheCorvetteman]

In my case it was certainly not a focus issue.

[AnalogRocks]

[AnalogRocks]