Resurrecting a Samsung S32D850T PSU

For many years my trusty Samsung S32D850T has served me well, both as a primary, then secondary screen. It's huge 32" size and 1440p resolution make it ideal for a nice clear screen for coding on. While my new shiny LG 32" 4K monitor is nice for general use, I prefer the older screen for coding work.

However, last year the PSU gave out again, this was not a surprise as originally this was my brothers screen and the PSU had dies on him after a couple of years. At this time I got lucky and sourced a broken screen unit for £50 from Germany, liberated the PSU board and we've been good every since. These days a replacement BN4400750A PSU boards, costs quite a lot more, if you can find one.

Reluctant to let the screen go I eventually stumbled across a most excellent post on, reading through and taking a punt I ordered the KF12N60 TO-220F from AliExpress, waited a few days and cracked out the soldering iron.

After following Wayne's guide and unearthing the MOSFET from it's silicon putty tomb I removed it and soldered in a replacement. I had a slight hiccup with one of the traces lifting when pusing the new part in, but it was still connected to the PCB so I just buried it in solder. Another thing to note was there was barely any thermal compund behinf the MOSFET, how it had survived a decade-plus of use under those conditions is a mystery. I put a hefty sploge of Artic Cooling MX-1 to ensure good thermal contact, it works well on my i7 @ 5Ghz so I'm sure this will do the trick.

After a test fire playing Samsung DEX content through it to confirm all was fine, I have reinstated it on my desk, currently testing as in a vertical aspect to see what I think.

  • Messy but solid soldering, I'm out of practice.

  • Testing with Samsung DEX playing YouTube content

  • Ready for another decade of use.