LG Ultrafine 5k 27MD5KA-B

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LG Ultrafine 5k 27MD5KA-B
Manufacturer LG
Code name
Release date 2017-04-20
Device type Television/Monitor


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Guides

Explanatory Guides

Repair Guides

 Affects partTypeDifficulty
LG Ultrafine 5k 27MD5KA-B Display completely unresponsive repairLogic BoardSoldering3. Hard
LG Ultrafine 5k 27MD5KA-B Display completely unresponsive test mode fails repairPSUPart replacement1. Easy
LG Ultrafine 5k 27MD5KA-B Randomly going to sleep or doesnt wake up repairLogic BoardSoldering3. Hard

Device pictures

PCB pictures

Reference measurements (also schematics if available)

More Information/External Sources

This model seems to have a prone-to-dying Texas Instruments USB-C PD + Thunderbolt multiplexer controller "TPS65983" as ive seen two (suspecting 3) models with it being the cause of the display not working. Issue can stem from other places as well, like power supply (fuses etc).

How to use test mode:

External references and other people having issues:

People complaining about loose main port: https://maker.pro/forums/threads/lg-ultrafine-27md5ka-b-provides-power-to-laptop-but-does-not-get-detected-by-computer-no-video.292861/

Cable issues: https://discussions.apple.com/thread/252555535

Francis (fronke_ on discord): These are my own observations, but a quick google shows others having similar issues.

I have had 3 identical models in for "not starting".

Display 1: Test mode works, fixed by replacing TPS65983.

Display 2: Test mode works, replacing TPS65983 has not fixed it.

Display 3: Test mode does not work, fuse "F100" faulty, not fixed yet (as of Jan 30, 2023, currently no updates).

Display 2 Update (2024-01-23): Ended up replacing the entire motherboard, display now works normally. The motherboards seem hard to come by.