Help: Diagnose Video Failure on T500

[ArtShapiro]

The patient is a T500, 2055-AS4.

Recently it has been sporadically (but more and more frequently) flickering. Dim-bright-dim-bright. Sometimes several times per second and sometimes much more slowly. Once in a while it loses almost all the video - suddenly goes almost black with an image barely visible. Hibernating and re-powering gives the normal video for a while.

Things are fine with an external monitor attached, even as the laptop's screen is flickering. This tells me that the video controller on the MB is fine. Therefore I postulate that either the inverter or the display panel are failing.

Is this a reasonable hypothesis? How do I isolate it further? Or do I simply replace the inverter because it's cheap, and see what happens?

And do I have to go through the full-fledged HMM disassembly procedure, or can I simply open up the lid to get to the inverter?

Thanks for any informed opinions.

Art

[ajkula66]

This tells me that the video controller on the MB is fine.

Not necessarily. Digital and analog output are carried from GPU via different lanes. One can be failing or even dead and the other perfectly fine.

Or do I simply replace the inverter because it's cheap, and see what happens?

That would be a good first choice.

And do I have to go through the full-fledged HMM disassembly procedure, or can I simply open up the lid to get to the inverter?

Lifting the LCD bezel should be enough from what I recollect.

Good luck.

[ArtShapiro]

Not necessarily. Digital and analog output are carried from GPU via different lanes. One can be failing or even dead and the other perfectly fine..

Oh bother!

This thing supposedly has switchable graphics, although I've never figured out how that works (apparently not in Windows 10, period). Should I temporarily put on some earlier OS such as the Vista that it allegedly came with, and see if switchable graphics affects the issue?

[ajkula66]

This thing supposedly has switchable graphics, although I've never figured out how that works (apparently not in Windows 10, period). Should I temporarily put on some earlier OS such as the Vista that it allegedly came with, and see if switchable graphics affects the issue?

I've got no wisdom to offer when it comes to W10, the graphics should be switchable in BIOS, though.

Boot a "live" Linux CD/DVD/USB and see how the system behaves in that environment. Report back.

Good luck.

[ArtShapiro]

the graphics should be switchable in BIOS, though.

Ah so!

Unfortunately for me, no difference, and in fact the BIOS screen itself is badly flickering. That tells me there's no point to trying anything like the Linux CD; this is purely a hardware issue.

Guess I'll purchase an inverter and see what happens.

Art

[ArtShapiro]

The replacement inverter arrived today. Alas, it didn't fix the issue.

I guess this machine is toast unless someone has a great suggestion.

I've been keeping an eye on eBay for a replacement T500, and for those few offerings that include an actual model #, most of the time the model is not listed in my TAW. This makes it rather hard to determine what screen resolution is present - I don't want to be stuck with a WXGA model. Is there some resource other than the TAW that tabulates Thinkpad models?

Art

[RealBlackStuff]

Alternatively: if your screen is OK (and it might), go for any working T500 with a cracked screen.
Its mobo should still be OK, so just replace its complete lid with yours..