Final Build Question & Display Issue[Update]

[alaszlo]

I just finished my Preenfm2 build with the metal case from Van Daal, and I have to say, much props to Xavier for designing such an intuitive synth! This is a 2-part post, the first part regarding my build quality and the second regarding an OLED display issue.

1. I noticed that, after screwing everything together on the metal case, there is a fairly significant bend at the top of the faceplate close to the screen. I would assume this is because of the plexi screen protector (Attached shows the case screwed slightly tighter than finger tight). Has anyone noticed this on their builds as well? I just want to make sure that I'm not putting too much pressure on the OLED after tightening everything.

2. After powering on the device, it boots up correctly (2.10) and the display remains on indefinitely if I don't press or turn anything (I timed this past ~2 minutes and then gave up). However, after I start pressing the various buttons and turning the encoders, the display turns off but I can still receive audio whenever this occurs. Every time the display turns off and I select 'Menu', a bunch of gibberish characters appear on the screen. Apart from that, some of the menus cause the OLED characters to flicker (notably the 'OP()' & 'Settings' menus). The rate in which the display turns off seems to be tied to how quickly I cycle between the different menus. 'OP()' & 'Settings' appear to be the main culprits as the display will shut off more quickly after pressing those. There are other random instances I noticed that have caused the display to turn off including: the display turns off immediately (uncommon), pressing only one button that isn't one of the two previously mentioned, and turning only the encoders.

Note:

• I'm powering the Preen via USB and the display behavior is consistent whether it's plugged into the computer or a USB wall adapter.
• My computer doesn't recognize the Preen as an external device when plugging into the computer (not sure if that's normal behavior).
• I removed the DC input in order to properly fit the case (likely not tied to the display issue if I had to guess).
• I have JMP1 & JMP2 connected but left JMP3 open.

Any ideas? I can also upload any photos of the PCB if need be as well.

[served]

Hello.

Please send a picture taken from the same angle but without the Bottom case part.
You can solder in the DC jack. There is no issue with it. If it doesnt fit. you need to solder it in a correct way so it fits.
The jack can be moved inside the PCB holes to make it align.

[alaszlo]

Thanks for the reply. Hopefully the lighting is good on this photo. I wanted to avoid tightening the case much more than it is to minimize any stress being put on the PCB. That and I didn't want to add too much pressure on the OLED with that screen protector in place.

As for the DC jack, it was definitely an issue with how I soldered it. Since there were three solder points, it was too difficult for me to desolder and realign, so I just had to cut it out of the board. I'll probably end up buying a replacement at some point.

[alaszlo]

Update on my build. I resoldered the OLED points both on the actually OLED and on the PCB as well (pictured). It seems as though the behavior has persisted where the display will randomly shut off after a brief time, usually within about 30 seconds. I also checked the solder points on the switches and encoders and everything looks clean and spaced out well.

[Javelin276]

Just looking at your photos, the second photo has me a bit concerned.  The solder in between the points looks like it's touching in a couple of spots.  It may just be the photo, but you should check it.  You might try doing a continuity resistance check between each pair of adjacent pins to see if the pins are separate, that the solder isn't cross connecting the pins.

[served]

Can you tell me the length of the Spacers?

Press that Plexy screenprotector inside the Frontpanel screen hole. It goes all the way until its sitting flat.

[alaszlo]

@Javelin276 It's actually just the board catching light between the solder points, but thank you for the suggestion. I'd do a continuity test, but alas, I'm new to soldering and don't have a multimeter yet. Those photos I posted were after I added a little more solder to each point and, unfortunately, the behavior is the same as when there was too little solder.

@served, I assume this is Ardi I'm talking to? The metal hex spacers are ~14mm. The previous photos show the plexi screen protector pressed into the front panel hole like suggested. It's situated such that the flattest, widest side is pressed against the OLED and the smaller side is flush with the outside surface of the metal case.

[served]

Hello,

Replace the OLED-resistor with a wire or Resistor leg. You have a Blue OLED screen. So you should have a 0 ohm there not 22ohm. Thats why the Screen shuts off.

Yes thats the correct way for the Plexy glass.
I cant see the reason why it doesnt fit. I just built 2 units from the same DIY kit patch and they all fit.
Try to push and resolder the Pinheaders for the Screen and Mainboard tighter together against the boards.

Best
Ardi

[alaszlo]

Ardi, that resistor was definitely the cause of the buggy screen. I replaced it with a spare resistor leg and everything is working now. Thanks!

As for the issue assembling the case, I think I'm going to just buy an adhesive screen protector as I can't seem to get the case mounted flush using the plexi  screen. I've attached a photo of what the pinheaders look like with the OLED mounted. It seems to be as tight as I could have gotten it. I'm not confident in my desoldering abilities, so an adhesive protector will suffice. Aside from the plexi screen, the rest of the build went pretty smoothly!

[served]

I will post you a new plexi glass. See if that works.
It has been CNCmilled a bit differently.

[alaszlo]

Much appreciated Ardi! Thanks for going the extra step to help troubleshoot my issue.