ThinkPad Edge E320 intermittent screen fault - CMOS related?

[rek]

Heya all, I've been given a ThinkPad Edge E320 to troubleshoot/keep/scrap for parts, or any combination of the above. What the issue is that the internal screen doesn't initialise (the backlight lights, but no information on screen - not even the Lenovo boot logo), but the system still seems to boot alright.

I've found that if I remove the yellow CMOS battery and let the system sit to drain, the internal LCD panel works just fine, and if you leave the CMOS battery unplugged it continues to work fine. However as soon as you plug in the CMOS battery and save the configuration, the problem starts again.

Does anyone have any ideas? I've tried different CMOS batteries (I have a few with the same connector from some old X60s and T60s I've scrapped for parts) and it doesn't seem to make a difference. I've also tried updating the BIOS to the latest version in one of the times I was able to get it to boot fine.

Another thing I've checked for are loose LCD connections (on both sides), any places where the system board shorts out on other places such as the back of the keyboard and HDD bay (which seem to be two common trouble spots), but the issue is quite repeatable/resolvable with the CMOS battery pull.

Any ideas? I've never seen anything quite like this before..

[RealBlackStuff]

That machine might have switchable graphics.
If you manage to get into the BIOS, go to Config--> Display-->Graphics Device.
Set it to Integrated and set the OS detection to Disabled.
Also check the Boot Display Device, set it to Thinkpad LCD.

[rek]

It's got integrated video, and I've tried all the boot display settings. It's really perplexing.

Thinking this is too frustrating to continue, and harvest the Socket G2 i3 processor for a mini ITX system board one day in the future.

[rek]

Hmm, just thought that the BIOS update I did didn't touch the EC, only the system BIOS.

Maybe if I reflash with a much older BIOS that has a different EC version, it might kick things back into gear...

[rek]

Nope, that didn't work. Oh well. It's a nice form factor machine with a real TrackPoint, shame it doesn't work.

Now I have an excuse to blow money on whatever little toy that has a Socket 989/G2 socket on it

[rek]

Turns out the cheapest thing to do with the parts is to buy another E320 motherboard and put the machine back together again. Here's hoping this solves the problem!!

[rek]

Very strange. A new system board and CMOS battery does not solve the problem!

Maybe one of the wires that outputs the EDID information from the LCD panel is broken, that's the only possible other explanation I can think of why it would work UNTIL the BIOS has had a chance to record something.

[RealBlackStuff]

Probably the only thing left would be to try another LCD cable.
They are made of such flimsy material, that it's easy for one of those thin wires to break.
Failing that, throw it over the Edge of a cliff...

[rek]

Good news. It did turn out to be the LCD cable after all (which of course is the only component that requires complete disassembly of the entire machine to get full access to...!)

Working fine now with a 256GB mSATA SSD and a 500GB 7mm HDD I had laying around.