Thinkpads Forum

My ThinkPad T420 has been upgraded with a LVDS to eDP board and a 1920x1080 panel, but the cable which connects the converter board to the panel seems to be going bad.

The cable appears to be a 40 pin eDP on one end and a 30 pin eDP on the LCD end. Sounds like something that would be easy to get at any well known auction site, but I cannot find one anywhere. Looks like I can get 40-40 cables, and 30-30 cables, as well as 40-30 and 30-40 adaptors boards, but no 40-30 cables.

Does anyone know where to get such a replacement cable from, or should I just go down the adaptor route?

Picture of connectors and wires for reference: http://stevecoates.net/thinkpad/edp_connectors.jpg

Thanks
steve30.

The adapter kits are very proprietary. For T420 and T430 they engineered their own LVDS-to-adapter cable with an inverted terminus pinout from the factory LCD cable (because it's a clone of the T420s/T430s kit which has an upside down motherboard LCD connector and connects to the adapter through a flexible flat cable, but digression aside:). It'd be no surprise to me if the adapter-to-EDP cable is a special nonstandard cable and I wouldn't count on it having a standard, mass-market replaceable pinout. EDP cables are not inherently standardized.

If it were me I'd order another FHD kit.

What makes you think the cable is bad? I find LCD failure more common.

I haven't buzzed out the cable on my multimeter yet as the pins are very small and I need to dig out my extra sharp multimeter probes, but the 40pin end looks like it just uses the first 30 pins, so unless it has some weird pinout, they really could have just used a standard 30-30 pin cable.

I'll see if I can get a 40-30 adaptor off ebay and a cable and try that, and I might see about getting a new FHD kit anyway, just to keep as a spare, or incase I acquire another T420 (I've had this T420 a couple of years now and rather like it).

I suspect the cable is bad because the screen flickers when I wiggle the cable, and it has got worse over time. I did wonder if it might have been the LCD (or its connector), but the previous owner did this upgrade and used a 1920x1080 TN panel, which was pretty low quality, so I recently upgraded to a much nicer IPS panel, and it exhibits the same problem where i have to wiggle the cable around.

OK, I decided to just order a new upgrade kit off Aliexpress. Hopefully all will go well.

steve30 wrote: ↑

Thu Jun 08, 2023 6:01 pm

My ThinkPad T420 has been upgraded with a LVDS to eDP board and a 1920x1080 panel, but the cable which connects the converter board to the panel seems to be going bad.

The cable appears to be a 40 pin eDP on one end and a 30 pin eDP on the LCD end. Sounds like something that would be easy to get at any well known auction site, but I cannot find one anywhere. Looks like I can get 40-40 cables, and 30-30 cables, as well as 40-30 and 30-40 adaptors boards, but no 40-30 cables.

Does anyone know where to get such a replacement cable from, or should I just go down the adaptor route?

Picture of connectors and wires for reference: http://stevecoates.net/thinkpad/edp_connectors.jpg

Thanks
steve30.

This adapter kit is very confidential. They reverse-engineered the factory LCD cable's terminal pinout for the T420 and T430 to use as an LVDS-to-adapter connection (as it is a copy of the T420s/T430s kit, which uses a flexible flat cable to connect the motherboard LCD connector to the adapter, but that is a digression for another time:). Having a common, mass-market replacement pinout would be a nice perk, but I wouldn't be surprised if the adapter-to-EDP connector is a bespoke nonstandard cable instead. Unlike other types of cables, EDP cables are not static.