video flashes under load

[kulcousy]

Hello All,
I'm working on someone elses T42 (2378 DUU- 2 months out of waranty) that has video periodically shutting down to only a faint screen or flashing. It works okay on external monitor. It's a T42. I've swapped cables and inverters. I haven't yet swapped lcds
The thing is that when the hdd runs is when the video blanks or flashes. The same is true of the cd rom during fast read. Any thoughts?
Thanks,
John

[sarbin]

"faint screen" meaning no backlight but you can see screen contents faintly? if so, it sounds like the backlight is on the verge of failing.

[kulcousy]

Thanks for your opinion Sarbin. That hadn't occured to me as a possibility. I could swap in another lcd but I'm not sure it's 100 percent okay. I'll try that.

[sarbin]

having a spare lcd to try is nice!
replacing just a bad ccfl sounds like a bear of a job. not one i'd try, anyway.

good luck.

[kulcousy]

I swapped screens. This one displayed only white but it did flicker a couple of times like the other. Also, I noticed that the hdd light is lit dimly when the computer is shut down though operates normally when running. The failing backlight combined with hdd usage makes me think there is a power drain somewhere. I'm out of ideas and don't know what to tell the guy. Maybe the power issue is related to a mainboard failure.

[sarbin]

well... considering you've swapped lcds, inverters and cables, just about the only thing is the planar. it doesn't sound like the gpu issue considering it works attached to an external monitor.

sorry...

[ajkula66]

The fact that it works when connected to an external monitor doesn't mean much. LCD output is digital, VGA is analog, it's perfectly possible (and I've seen it quite a few times) to have one messed up while the other one remains operational. And in all of these cases it was a GPU problem.

[sarbin]

i learn new things every day... thx!