Display not working on MK4S
My MK4S had been working fine until I booted it today and the display did not light up at all - nothing. It is like the display isn't powered. However, the fans ran fine and I was even able to print once using PrusaConnect. My last boot was a couple weeks ago but I believe on that boot I upgraded to firmware 6.4 so that seems suspicious.
I contacted support and they asked me to re-seat the display ribbon cable but that didn't help. They suggested I downgrade to firmware 6.2.6 (tricky without a display but I think I did it) and that didn't help either. Unfortunately, after that one print once the display went dark, the printer no longer connects to the network anymore so no PrusaConnect. However, it still seems like it boots fine - i.e. the fans run for about 5 seconds then stop and then I hear the beep.
Support said they'd have to think about this for a few days so I'm posting here hoping someone else has some suggestions I can try in the mean time.
I could try to "ohm out" the ribbon cable to see if there is a broken wire but I hate to just waste time if that isn't a suspect. Again, the printer ran fine until today and it hasn't been moved or anything. The only recent change was the firmware upgrade.
RE: Display not working on MK4S
Replying to my own post. Support now tells me that my printer is a month out of warranty and I need to purchase a new xLCD board for over $135 - not happy. I wish I'd gotten a Bambu.
RE: Display not working on MK4S
Just in case anyone else travels this path, I received the new xLCD and it works - i.e. it is the xLCD and not the ribbon cable coming from the xBuddy board.
In comparing the two assemblies, the old one, dated 2023, has a very funky dual-flex (FFC) connection between the PCB and the panel sub-assembly. One of the FFCs has a reasonably large chip embedded in it and, unfortunately, the FFC does a tight 180º turn right where that chip is - no bueno. This has been entirely designed out on the new board. I have no way to tell for sure but I suspect this was the problem.
Since the panel was entirely dark, I tried the usual power suspect - i.e. the LDO that supplies 3.3V to the board. The 3.3V output was rock solid and reached all the right places on the board. It is very nice that Prusa supplies schematics though I think the currently posted one might be for the old board (?).