MD Screen replacement LED issues

Hi elektronauts,

I recently swapped out the screen on my MD and it look flawless, but some issues happened with the LEDs glowing when they shouldn’t. I re-soldered all connections, even reinstalled the old screen but the issue still persist, so my guess is that I messed up with one of the traces :frowning:

I tried to check all the connection pins with multimeter, but I don’t have wiring diagram (only visible through pcb), so I didn’t get enough information about which of the pins can be a faulty one. Also, here’s a picture, where you can see the LEDs glowing (like BD and RS, Classic mode and etc.)

Any help/ideas would be really appreciated (or even if someone has a wiring diagram :smiley:)

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I don’t have a diagram, but the screen is controlled by a PIC on the UI board. I dumped the firmware for the MK1 PIC, I have absolutely no clue if it would be usable with a fresh PIC in your machine (IIRC they have used the same class of PIC in all of this era of instrument with the only differences being in how they’re flashed… I kind of doubt the firmware is much different since the only change is… 1 extra LED?). At the very least you can try reflowing the pins on the PIC OR if you’re ultra lucky and it’s socketed (I think a few of them were) you could dump it if you’re feeling extra brave and we can compare notes.

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Hey there - this is the closest I found to my issue. I need a new screen for my MD MK1, but cannot find proper documentation and neither does Elektron want to give me a part number.

could someone verify if this one will work:

i have a similar issue with different led’s. did you ever get to the bottom of this?

So for everyone interested - I’ve managed to fix this.
The pins on the bottom of the motherboard, which are used for the screen are the same pins, that are used for the LEDs. So basically I’ve checked that all the pins are soldered properly and found a couple of faulty ones (which is my fault, I would advise you to not to try to desolder from the bottom, but desolder the screen itself). Reflowed the connections and everything is working fine.