eDP cable for "upgraded" Thinkpad T420 LCD

[steve30]

My Thinkpad T420 has previously been upgraded with a board which converts the standard LVDS display signal into an eDP signal. Unfortunately the cable seems to have gone bad and I'm not sure what I need to look for as a replacement.

The connector on one end is the standard 30pin eDP connector, but the connector on the other end is 40 pin. Do I just look on ebay for a 30pin to 40pin eDP cable? See attachment to see the connectors.

It may seem obvious to some people but laptops have so many weird combinations of connectors, and mod boards like this can only serve to complicate matters.

For reference, here is an example of the LVDS to eDP mod board: https://www.ebay.co.uk/itm/234900511350

Thanks
steve30

[SiliconWizard]

I happen to have made this mod on a T420s a few years ago!
Actually in my case, I think the eDP cable has been getting bad over time - the image now tends to have some occasional grayish artefacts on the left side, which disappear when I twist the bottom left of the display a bit where the cable goes. Haven't investigated the issue more than this yet.
But I was certainly happy with the mod at the time, allowed me to install a FHD IPS panel instead of the original panel which was meh.

[steve30]

A previous owner of mine did the mod with a 1920x1080 panel (so an upgrade over the original), but they used a TN panel which had terrible colour and terrible viewing angles. I have just replaced it with an IPS panel which cost about £40 on ebay and is much better. The issue with the cable started a while back. I have to keep moving it around to stop the image from disappearing.

[james_s]

This is intriguing, I'm typing this right now on a T420 which is a great machine but the display is pretty crap. I'd love to swap in a more modern IPS panel.

[steve30]

james_s: It is a worthwhile upgrade, and 1920x1080 IPS panels are quite cheap now, here is the ebay link for the one I got: https://www.ebay.co.uk/itm/272486689947

You just need to try and install the LVDS to eDP converter board which you have to get from eBay or Aliexpress. I believe they include the cables.

[james_s]

Thanks, that's a UK only seller but it gives me the part number, looks like that panel was used in a handful of different laptops.

Do you happen to know what specific converter board is needed? Are there any issues with the conversion or does it just work?

[steve30]

Thanks, that's a UK only seller but it gives me the part number, looks like that panel was used in a handful of different laptops.

Do you happen to know what specific converter board is needed? Are there any issues with the conversion or does it just work?

Its the type I mentioned in the first post (https://www.ebay.co.uk/itm/234900511350). They seem a bit pricey; I don't know if you can get them cheaper. There are a few topics on various forums about the mod if you do some Googling. There are quite a few different LCD models you can pick, but they are all practically the same (some may be gloss vs matt etc, but the listing ought to say). It seems to work fine for me. Windows and Linux will just see a normal 1920x1080 display. In my case, the mod board is sellotaped behind the LCD panel, but others seem to put them in the main body of the laptop.

FWIW, I gather the "T420" is different from the "T420s" and therefore needs a different mod board.

[Infraviolet]

These styles of wires are absolutely the devil's own invention. Utterly tiny strands located in the most precarious positions, no physical support but the black cloth tape around it which often has to be pulled aide to connect/disconnect the connector from whatever it goes in to and often is partially stuck down to nearby boards, individual wires all totally separate so a single one can snag trivially where wires of a ribbon type cable couldn't, some slots on the connector empty so you wouldn't know where to resolder a broken wire to... I've had some horrifying near misses with this style of wire when trying to get past it to replace other internal parts on laptops, if the near misses hadn't quite missed then the machine I'm typing from today would be permanently dead.

[james_s]

I'm not a big fan, however for most laptops I've dealt with you can easily buy replacement cables so there's no reason for it to be permanently dead.

[steve30]

It looks like the cable is a straight forward 40 pin to 30 pin eDP conversion... except I can't find a replacement. I can get 40-30pin cables from China on ebay but they just have the connector on one end. I can probably get a 30-30pin cable and a 40-30pin adaptor separately.