CurtPalme.com Home Theater Forum

freedomland · Joined: 09 Jul 2025 Posts: 7

Hey there,
I am new to the forum and wanted to get into things with my newly fetched CRT projector. I havent paid anything for it, has just 430H on the clock, no sign of tube wear, the insides looks fantastic and the image appears to be spot on on the tube surface.

The weird thing is here:

When I work with no video signal on and just use either the menu or internal test patterns, everything is normal and how things should are. As soon as a composite, HDMI or RGBHV is going in, the picture either have a vertical missing block of line with higher resolutions(HDMI) and also some wavy sides, either on the upper or lower end of the picture. With composite or RGBHV I just get the letter mentioned waviness.

To add some to this weird behavior, when I change to RGBHV or HDMI(1.3 board) it takes some time and/or a couple of resolution changes to sync the projector to the signal. In some resolitions which are then accepted, the picture is then ok with abovementioned behavior plus grainy and a wobbly/shaky and unstable picture is the result. In some resolutions the picture is stable but has the wavy upper or lower end wavy so a unmoving image problem.

I dont know if this is related to this problem, but at least in composite the color reproduction seems quite a bit off. I had good colors with the HDMI board, at least with a bare minimum convergence setup.

Anyone here, who could assist? I mean it would be a bummer to let this littler boy go into the dumpster. I would be willing in changing caps, adjusting pots or what ever is reasonable to solve the problem.

Is there a service menu which shows voltages of certain caps?

Thanks! Smile

**Curt Palme** · Posted: Sat Jul 12, 2025 11:01 pm Post subject:

A couple of possibilities. The XG didn't display 1080p properly without running through a scaler, to adjust for image wraparound. It's the back porch settings if I remember correctly that mess with the XG, and you get left/right image wraparound. Try running 720p.

Components age just from sitting there. THe weak point of the XG series was the main microprocessor board, the 4188. Your lack of syncing up would make me guess that's your problem. THey are not repairable, a few techs tried back in the day, which is why the XG series was one of the first I got rid of as they started failing. There is probably no cure here if it is the PWC-4188 that's bad.

**kal** · Posted: Sun Jul 13, 2025 2:02 pm Post subject:

You asked about service manuals. They're on the site here: https://www.curtpalme.com/NECXG_Downloads.shtm

Now that said, the XG is an incredibly complex machine compared to most CRT projectors and service manual procedures. Do not, under any circumstances start turning pots without first making sure you know what they're for and have a 'scope to adjust things correctly.

Kal

freedomland · Joined: 09 Jul 2025 Posts: 7

freedomland · Joined: 09 Jul 2025 Posts: 7

freedomland · Joined: 09 Jul 2025 Posts: 7

Quick question, I couldnt find anything helpful in what the amplitude setting is there for? And what is the ideal setting, H 100% as it was in the first place and vertical?

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

I second Kal's warning. DON'T TOUCH any of the internal pots unless you know what you're doing -- and you don't. There used to be a guy out in LA (Doug Baisey) who was our XG wizard, but sadly he's long gone. He gave me some tips on tweaking my XG582. I had an oscilloscope and used his guidance to improve my XG, but it was still not exactly right.

freedomland · Joined: 09 Jul 2025 Posts: 7

freedomland · Joined: 09 Jul 2025 Posts: 7

Dont mind the horizontal lines in the following pcitures, those are from the camera shutter, the vertical lines are the ones which are there to see.

Here you see the internal test pattern in the green tube, all others looks the same:

Here an internal test pattern all white in the tube face, also a vertical line on the one side:

Here all white on the wall projected:

Same in detail:

This is how it looks when a RGB-source via RGHV is displayed, the vertical line is not tracable and its not shown in the tubes nor the screen:

Setup is as follows:

I used my notebook as source with 1920x1080, hooked it up with my Corio C2250A via VGA to RGBHV to the CRT. Scaled the image to 60Hz(or 59...)1980x1080 interlaced, as this was the most reliable at the time of taking the shots. I might try 720P as well, but I constantly lost sync, so I ended up using the resolution which gave a stable image to begin with.

Dont mind the alignment or the convergence, its a basic setup for testing resolitions etc, the projector has not got a proper placement yet. What do you think about this artifact? BTW, with no video is sourced, the internal test patterns looks perfectly. Is that anormal behavior?

freedomland · Joined: 09 Jul 2025 Posts: 7

Besided, I havent centered the image yet. As dumb-proof the guidelines seems to be for centering the image, the odd behavior with all these settings discouraged me somehow. For the width, do I use the amplitude settings? And how am I able to maximize the picture size with the nec? In "position"?

**Curt Palme** · Posted: Sun Jul 20, 2025 6:59 pm Post subject:

scir16v · Joined: 02 Jan 2009 Posts: 113 Location: St. Louis

I have an XG 135 and I also have a scope. With that being said, I did have to reduce the drive by turning a pot. But you should not have to from the looks of the tubes. It would be wise to get a lumagen, then you could adjust the front and back porch settings to correctly resolve 1080.