White Screen With Replacement Motherboard

[wireman]

Hi All, Hope somebody can help me again.

I bought a second hand T21 motherboard off ebay to replace my old blink Of Death afflicted T20 motherboard. However now my LCD panel is completely white when it switches on.
The rear VGA connector works fine so at least I can see that the motherboard appears functional in all other ways.
The LCD was working fine recently until my old T20 motherboard packed in.
I have tried wiggling cables and even removed the LCD completely to check the connectors but all seem ok.
The white connector on the motherboard seems ok also.
I have had the old T20 motherboard out several times so I dont think all of a sudden the cable broke the minute I put a new board in.

Is the T21 motherboard compatable with the T20 LCD ?
Would the CPU on the new one ( 800Mhz ) make a difference as opposed to the 700Mhz on the old one ( unlikely I know but ... ).
The previous owner of the T21 motherboard says it was working when he sent it but whos to know ?

[vanaya]

What is the model # on the old board (2647-xxx)?? and what is the model # on the new board?? This way you can check what type of lcd was matched to it from the factory.

[wireman]

According to the Hardware Maintenance Manual.

T20
v 13.3-inch, 16M colors, XGA (1024×768 resolution) TFT color LCD
v 14.1-inch, 16M colors, XGA (1024×768 resolution) TFT color LCD

T21, T22, T23

v 13.3-inch, 16M colors, XGA (1024×768 resolution) TFT color LCD
v 14.1-inch, 16M colors, XGA (1024×768 resolution) TFT color LCD
v 14.1-inch, 16M colors, SXGA+ (1400×1050 resolution) TFT color LCD

So the T21 motherboard should be able to drive the T20 LCD.
I will check the LCD model again but I think it was Hitachi 14.1 XGA.

I definately can't spend any more money on this laptop. Its had a new battery, extra ram, hard drive and the motherboard already.

[tfflivemb2]

Be sure to check that the cables are properly seated...I have had that happen a few times in the past, when I was in a hurry to reassemble a system.

[Robbyrobot]

The rear VGA connector works fine so at least I can see that the motherboard appears functional in all other ways.

Unfortunately, this doesn't mean the mainboard is completely OK. I have a T21 mainboard where there is no backlight on the LCD screen (not due to the display = panel, inverter, cable) but an external monitor works fine.

Is the T21 motherboard compatable with the T20 LCD ?

As far as I know, there should be no problems with the XGA (1024x768) screens.

The previous owner of the T21 motherboard says it was working when he sent it but whos to know ?

Strange things happen, and the mainboard may well have worked properly under the previous owner's settings. That's not to say it will under yours.

[wireman]

I powered up the laptop outside of its case and checked all the components underneath. The AGP chip seems to get ridiculously hot to the point where I can't touch it. Its a BGA IC. Perhaps this is the problem ?
I have my old motherboard where that IC was ok. Shame I cant swap the chip.

Still the nice guy on ebay refunded my money for the T21 motherboard. No questions asked. Must find another one now.