Hi there! I did a screen replacement on my Analog Keys using the 122x32 screen from Crystalfontz that was mentioned in another thread quite a while ago. Unfortunately despite it getting power it does not display any text. I have checked all the solder points with my multimeter and everything is getting a good connection and nothing is shorted, so I don’t think it’s an issue with my handiwork necessarily. But I also had it powered up with the case open and turned the contrast trimmer to both endpoints and at no point in the range did it get clearer or display anything besides a plain blue screen. I am attaching images of the powered up screen (video is too big to upload) and my solder job, if anyone knows where to go next I would appreciate some help, thank you! Especially for anyone who has done a screen replacement themselves. I’m curious if maybe the display I purchased is not compatible, but my research lead me to believe it was which was why I made the purchase. Screen from crystalfontz
I don’t know anything about this particular display or your use case, but when you purchased this screen, was it sold as an AK replacement or was it the reference in a thread here that lead you to believe it was compatible?
Size-wise and pin-wise it definitely looks compatible, and I think if anything were going to pop or start smoking it probably would have already done it. My basic understanding is that some aftermarket screens on some devices require the addition of a resistor to make the display contrast compatible, something about limiting the amount of voltage that it’s able to receive in order to insure compatibility between what the machine puts out and what the screen wants to receive.
Maybe go back to the thread where you found this display and see if there is any mention of changing or adding a resistor? Or possibly quote the OP and ask if they had to change the fixed resistance which powers the display?
Beyond that, there are no glaring issues in your photos and the backlight is working so one would believe that either it’s getting no signal or it’s unable to display for other reasons. I assume the backlight could certainly work independently of the screen text. You tested it with a multimeter so I don’t think you can personally do more other than a little googling about the screen itself and compare that to specs for the original. You could possibly test some resistor values in-line to the voltage input and see if there is any visible change on the display.
Overvoltage would destroy it, but I don’t think undervoltage will hurt anything so it’s probably safe to try a few resistors, however when in doubt, go to someone with more experience and let them figure it out.
Hopefully it’s something simple but just at a cursory glance, it doesn’t look like you did anything physically wrong, and your tests seem to have confirmed that. Good luck, I hope you can get it working without too much hassle. I wouldn’t desolder it just yet, dig for a little more info before you make more work for yourself.
(FWIW I think that if the contrast adjust does nothing, it may indicate that the baseline voltage is outside of the range where contrast can be adjusted since the adjustment pot is essentially an analog variable resistor and above a certain threshold you’re just adjusting from “above max” to “higher above max”, which would visibly produce no measurable result).
Thank you for that detailed response, your suspicion sounds like what I thought might be going on as well. Unfortunately my electronics knowledge is not quite the best so I have to take a closer look at how I could add a resistor into this setup to achieve the effect you mentioned. To your point about the original thread, @noiseg33k mentioned it could be a direct drop in but I am not having that experience myself (if you see this @noiseg33k please chime in, I could use some assistance! 
). I bought the replacement screens years ago and must not have done that research back then to see whether this replacement is exactly compatible 100%, and now a few years later I just decided to give it a stab and replace it. Definitely not the best idea on my part, but hey, here I am. I will do some more digging and write back if I have any success fixing this. Here is the link to the original thread in case anyone remembers this discussion or wants to take a look: Analog Keys - New LCD Screen - #38 by noiseg33k
Ok, no problem. I’ll see if I can think of anything else. Sorry that I couldn’t help more but a lot of this will probably come down to the specific display unit. Physically I think it all looks ok and the unit must be somewhat compatible to get power and not start smoking, but incorrect voltage could result in no visible information. If I dig up anything I’ll let you know, unfortunately it looks like that other user hasn’t checked in since early last year so it may be unlikely that we get an opinion, although tagging them was smart. Hopefully they see the notification!
I ordered a new display from the elektron support a few weeks ago. Costs around 15-20$ + shipping.
So, I looked at the original post made by the person who recommended the display, and that other user seems to indicate that no resistor is necessary for brightness. I went to the product page and there is a notice which says that the part is at the end of life and is being / has been replaced by a different part.
I know you said that you ordered this a while ago, but are you able to confirm that they sent you the first part number ( CFAG12232A-TMI-TA ) and not the one listed on this notice?
I don’t think they’d call it a replacement if it weren’t retro compatible but I’m just trying to look for any possible clues.
Thank you! Good to know that the option exists. I may go that route if necessary.
Hi, thank you for continuing to look into this! I haven’t had a chance to do much more digging myself, but I do not remember that notice being there when I ordered it, and I confirmed the model number from my original order is not the new one. Still, good to check every possibility, so thank you!
Following this as I’m considering a screen replacement as well.
@BlastPast also making sure you have seen this OLED screen replacement available, in case they might have info, or in case you need a different replacement.
It was posted in a different part of this forum, and I hadn’t seen it till just a week or two ago:
There should be a trimpot on the analog keys for setting contrast, you just need to trim it a little.
Per the original thread
As far as I remember the trimmer for contrast is about an inch or two to the right of the LCD on the Keys, on the main panel board. If you’re unsure, follow the traces from the trimpot back to the screen to make sure its the correct one.
Hi, thank you for replying! Yeah there is a trimpot for the contrast, unfortunately I turned it entirely clockwise to counterclockwise and it didn’t have any impact on the readability of the new screen. I am considering just dropping the old screen back in and hoping that I can just adjust it to a readable point again, since the original point of replacing it was that it was getting hard to read the edges of the display due to some fading.
In that case I’d recommend checking your soldering, looks like you may have a cold joint or two.