CurtPalme.com Home Theater Forum

[stefano973]

Hello everybody, I own and use with great satisfaction a NEC XG75 ceiling mounted since 2003.
During all these years I performed several alignment/convergence/calibration processes, always without any problems.
Initially it was driven by an HTPC with a 576p signal @100Hz, then I reset everything for 1080p @48Hz and have been using it in this setting for last 5 years.

Some days ago I had a strange problem, that caused the serious issue I am writing about, for no reason I switched from Input 1 (the only one stored) to Input 3 on the remote controller, and when I returned to Input 1, all the setting configurations of the projector where lost and the resulting video was messed up.

No problem, I thought, I will redo all the setup from the beginning… I set to zero all controls and started a new calibration.
But I had a very big problem with raster vertical centering: while in the past I used to leave STATIC vertical control for GREEN to 0% (I set REF. ADJ --> RASTER CENTERING to -100%), and tune STATIC controls for RED and BLUE to few percent to obtain a perfect convergence at the center of the screen, now @ 0% STATIC the GREEN test pattern is definitively off center and very shifted towards top side, very high compared to RED and GREEN.
Moreover, I noticed that now moving REF. ADJ --> RASTER CENTERING from +100% to 0% shifts correctly all RGB test patterns towards the bottom, but going on from 0% to -100% the GREEN pattern stops moving and only RED and BLUE ones keep shifting towards the bottom.
Something has biased the vertical position of Green raster in a way that prevent a correct setting.

I know it is not a good idea to use so high values of STATIC control, because it could cause high stress of electronics and convergence instability, but I tried anyway to proceed on alignment process for Green component setting STATIC vertical control for GREEN to – 100% (and REF. ADJ --> RASTER CENTERING to -100%) , apparently obtaining a good result with test patterns, but when I switched to video image, I could not shift the image Position down to the bottom of the screen because the image started to scramble the lower lines, as if an electronic/sync limit was hit (video image too next to raster lower edge? Is there a limit?...).

I also tried other video resolution / refresh rate combinations, but I had the very same problem.

I want to understand what is happened and how can I recover a normal GREEN Raster vertical centering. Otherwise the projector is unusable in these conditions.

Please, help me to find a solution.
Is there an hidden/service control to set raster centering other than REF. ADJ --> RASTER CENTERING, or a physical trimmer in some board?

Thank you for your support

Stefano

[Curt Palme]

This is most likely a glitch in the system board, which is also why you lost your memory settings. I've seen this about 12 years ago, when one corner of the red point convergence would not adjust, and had a bend in it. I changed every board, and as a last resort, I reset the EEPROM. That took care of it.

if you do a full reset though, you lose all color balance settings, as they default to 50%. You'd then have to follow the procedure to set up the G2 settings on the main site. It's quite possible though that your system board is failing, and you'll need to replace it, as this may happen again.

[Curt Palme]

This is most likely a glitch in the system board, which is also why you lost your memory settings. I've seen this about 12 years ago, when one corner of the red point convergence would not adjust, and had a bend in it. I changed every board, and as a last resort, I reset the EEPROM. That took care of it.

if you do a full reset though, you lose all color balance settings, as they default to 50%. You'd then have to follow the procedure to set up the G2 settings on the main site. It's quite possible though that your system board is failing, and you'll need to replace it, as this may happen again.

[stefano973]

Thank you very much Curt for your quick answer, so I can try this full reset of the EEPROM.

Is it something I can do by the Remote Controller, or do I have to use the PC Control software and an external PC?
What is the correct procedure?

[Curt Palme]

Can you email me at curtpalme at shaw.ca?

thanks!

[Curt Palme]

Can you email me at curtpalme at shaw.ca?

thanks!

[stefano973]

I solved by just deleting all entries in ADJUST --> SIGNAL ENTRY list!!!
Apparently something in memory was wrong, and prevented a normal range for raster position controls.



Now I have full control, as it was before.

Thanks for your kind support.

Regards
Stefano

[stefano973]

Very strange: at the end of the calibration process, the problem was still there.

It seems that at the beginning, when all the entries are deleted and you start with a new entry, the controls are OK, but after having performed some of the settings and saved, the control range for raster position gets limited.

I think I'll try the reset of the EEPROM.