LCD backlight on, no characters

[JohnG139]

Hi.

This is with my latitude LM P133

The problem started when I fried the motherboard flashing BIOS A06 (from A11).

I got a new MOBO (actually two) and now the system boots up normally, but the LCD shows no characters, however the backlight is on.(It seems a little dim, but I do not know how bright this should be with no data feed from the CPU).
I bought a new LCD on E-Bay, 'guaranteed' not DOA. I had to take apart the bezel, remove the LCD panel, and flex cable so that I could thread the flex cable through the narrow slot in the upper MOBO case, but I was very careful. NO JOY! the problem remained. I had no problem with flex cables or ZIFF connectors with other components. Are these really tricky with the LCD or?? Using an external monitor, I successfully installed my OS, so it seems to me that the problem lies with the LCD, not with the MOBO, screen memory. Is there any other component on the motherboard specifically for the LCD? Are both LCD panels dead? How likely is it that I killed the LCD panel flashing the BIOS?
Since the system is normal with an external monitor, I cannot see any problem with the MOBO (I have tried both motherboards). Both flex cables appear undamaged. Is it likely that the problem is with the inverter? What is the likelihood both of them are shot? Would the inverter become damaged when a motherboard is fried with a bad BIOS flash?

Any help would be much appreciated.

Thanks,

John

[Phaelax]

If you can't see any characters, then how'd you install the OS?

[JohnG139]

System works fine with an external monitor,
John

[bobchang]

I'm probably too late on this one, but it sounded like the wrong BIOS was flashed into this LM-P system. As I recall, the LM-Ps were sold with both active (TFT) and passive (DSTN) displays. Now, in the early days, before auto-detect and auto-sensing features were available, notebooks weren't quite smart enough to know what type of LCDs were attached, and had to be told specifically by the motherboard how to deliver signal to different LCDs: most of 'em use the system BIOS to do the telling (most Dells), while a few resorted to separate video BIOS (DEC), still others relied on dip-switches (CPQ, Acer), and a few used different intermediary video boards to brute-force their way thru (Toshiba, some Dells), blah blah blah...

Sounds to me like you have a LM-P with an active LCD, then you might have flashed it with a BIOS that was meant to produce DSTN LCD output; or if you have a LM-P with a DSTN LCD, then you might have flashed it with a BIOS that's meant for active LCD output. The signal is getting sent up, I'm sure, but it's like me speaking Chinese to a Mexican - no comprendo, and hence the "blank stare..." and of course, all your extra work went for naught. :cheesy:

Suggestion: locate the rightful BIOS for your system, and flash it back. That oughta do it.