T40 SXGA+ upgrade

[ascendant]

I'm in the middle of a project to upgrade the screen resolution on my T40 (sig), and was hoping for a little input.

I got a Quanta panel (QD14FL07) a while ago and popped it in expecting it to be compatible. Of course, it didn't turn out to be plug and play which is why I'm making this topic. It seems some other people have tried this before with different model thinkpads with, ahem, dramatic results. Not so in my case.

The panel sorta works. I can set a resolution up to 1280x1024, but the display only shows the left half what it's supposed to. That image is stretched across the whole display, and every other vertical line of pixels is black. The panel itself is capable of 1400x1050 and shows up as that in the list of displays, but Windows does not offer that resolution.

I would like to make an attempt at convincing the ATi chip to send a signal to the screen that it can display correctly. Failing that, I'd like to understand a little more about why such a undertaking is a pointless waste of energy. The Quanta panel was quite cheap, so I don't mind too much simply writing it off and picking up an official screen off eBay later.

Reiterating for clarity: I have a IBM XGA panel/cable, a IBM SXGA+ cable, and a non-IBM SXGA+ panel. The motherboard has not caught fire due to having a non IBM panel attached to it.

[Neil]

It's the cable that tells the GPU what resolution to set on a T40. So, if you are using the SXGA+ cable with the Quanta panel and still getting resolution/display issues, it must mean that the panels connector is not exactly compatible with the T40 cable.

I've seen similar issues with mismatched LCD/cable combinations, but always with both ThinkPad cables and panels.

The panel itself is capable of 1400x1050 and shows up as that in the list of displays, but Windows does not offer that resolution.

I'm not sure what you are saying here, but it may be true that "Windows" (the generic Windows graphics driver) doesn't support 1400x1050, if you have the right ATI driver installed it will.

Best bet would be to get a working T4x SXGA+ complete lid, and just bolt it onto the T40.

[ascendant]

I mean that the panel is physically 1400 pixels across, etc. The driver I have installed reports the chip as being capable of 1400x1050@50Hz in its list of supported modes, but it could still be a driver issue. The laptop is running Windows 7 and is using the hacked Vista drivers downloaded from this forum.

One thing that worries me is the fact that even though the laptop's built in monitor shows up as "1400x1050 Thinkpad Display," Windows will only let me select resolutions up to 1280x1024. I hope it's just the panel reporting that it won't run at 1400x1050@50Hz. Not sure if that's possible, since supposedly the video chip doesn't query the screen directly for an EDID or otherwise determine what the screen should and shouldn't be capable of.

Thanks for your post, though.

[RealBlackStuff]

Hunt around for datasheets of the old and new LCDs, then compare the pinout of each.
If pins are different you need to do some intelligent DIY.

[ascendant]

Looks like the Quanta panel is designed to receive a double wide LVDS signal, while the thinkpad only gives it a single channel. In a double wide configuration, pixels are sent as even/odd on each channel.

http://thinkpad-forum.de/threads/31601- ... SXGA/page2

It would require logic to decompress the signal into a format the display can understand, and there's no room for any of that. Oh wells, at least now I know why it can't be done.