GT black and white display issue

[bdoi]

I juste recapped a GT with a clean MB. but colors and brightness was washed. So I tried a LCDDRV screen and the display is just in black & white.
Any thought? a bad HuC6280? I thought to test a composite mod to see if there are any change

[Keith Courage]

I recently worked on an express with a similar issue. Green is messed up with both an original screen and the LCDDRV. I tried tracing the green signal from the hu6260 chip but couldn't figure out why it wasn't displaying correctly. Maybe the hu6260 chip is faulty?

So I did a composite mod which looked normal and turned it into S-video by separating the Luma signal from composite. Looks pretty good on the LCDDRV.

[MasterofBiscuits]

The LCDDRV boards have really poor quality control, I had one that was B&W and it turned out to be a bad connection on one of the pots that controls brightness/ contrast etc. I would recommend going over all the joints on the LCDDRV board with a soldering iron just to make sure.

[bdoi]

The LCDDRV boards have really poor quality control, I had one that was B&W and it turned out to be a bad connection on one of the pots that controls brightness/ contrast etc. I would recommend going over all the joints on the LCDDRV board with a soldering iron just to make sure.

Yes may be some LCDDRVboard have some issue but there is an issue before the LCDDRV board so i don't think the issue comes from it this time

[bdoi]

So I did a composite mod which looked normal and turned it into S-video by separating the Luma signal from composite. Looks pretty good on the LCDDRV.

Thanks, so you maje the composite mode and after modify it to make rgb mode?

[MasterofBiscuits]

The LCDDRV boards have really poor quality control, I had one that was B&W and it turned out to be a bad connection on one of the pots that controls brightness/ contrast etc. I would recommend going over all the joints on the LCDDRV board with a soldering iron just to make sure.

Yes may be some LCDDRVboard have some issue but there is an issue before the LCDDRV board so i don't think the issue comes from it this time

Could be, but for 5 mins work I would recommend doing it. If you have a spare original screen, I would also try testing with that so you can try and isolate where the problem is coming from.

[bdoi]

Yes i have tested 2 different stock screen and same issue so the issue came from the mother board not from the screen itself

[Keith Courage]

So I did a composite mod which looked normal and turned it into S-video by separating the Luma signal from composite. Looks pretty good on the LCDDRV.

Thanks, so you maje the composite mode and after modify it to make rgb mode?

I didn't mod for RGB. The LCDDRV screen can also use composite or S-video. So I did the composite mod to the Express and then disconnected the Luma signal from the composite signal, amped the Luma signal using the traditional transistor method, and wired up S-video to the LCDDRV screen. Looks and works great.