Screen flickering or completely turning off at different angles

[sygyzy]

Last night I disassembled my mintyPi to fix an A button issue. I previously have had no issues with the screen but this time, when I put it back, I noticed that the screen only works at certain angles (about 85-100 degrees). I thought that it had to do with the ribbon cable flexing so I tried holding the cable against the back edge of the tin (to isolate it) and moved the lid back and forth and I can repeat this behavior. I can get the screen to turn on and off by moving it slightly back and forth. I tried seating and reseating the ribbon cable on both ends (screen and board) and nothing seems to help. I thought that maybe some of the solder points between the Pi and board broke so I checked continuity and they all seem good.

Does anyone have any ideas? The irony is I spent all this time fixing the last issue (A button responsiveness) and now the screen doesn't work.

Any ideas would be appreciated. Thank you.

[rodocop]

hmm, is this one of Helders board where the screen is direct soldered to the board? Or is it the one with the connector? If it is direct soldered you can try to just brush a hot iron over the connections to re flow them a bit. I've had similar issues with another SPI screen in another project and after reflowing the board connections it started working again.

Just to be clear, it works, but can only be seen when held at an angle? The exact issue I had was slightly different and the screen would just randomly go black and not turn back on until I reset the device.

I've never really heard this happen, I hope you can get it resolved!!

[sygyzy]

Hi Rod, thanks for the quick response. This is his latest board that uses a removable ribbon cable connector. The screen functions (mostly) when held at a certain angle, completely shuts off at any other angle, and resumes working at the right angle. Once in a while if I play with it enough (moving the angle back and forth), the screen will go white (not off, is still backlit). When this happens, it acts the same as above, except whenever it is active, it'll just show white.

So the two scenarios are:

Correct Angle - screen works, shows RetroPie. Bad Angle - screen off

OR

Correct Angle - screen works but just shows a white screen. Bad Angle - screen off.

[rodocop]

okay, so what I was saying was actually re flow the solder on the board where the screen connects. His newest board has a screen that is direct soldered and then a connector that is used with the ribbon cable to attach to the board. See image below from Helders post, reflow where the screen connects.

But since it seems to stop working when the screen is moved my suggestion does not seem like it will work....Have you checked the continuity of the ribbon cable itself? it's very odd, if you can't resolve it, maybe contact Helder to see if he has any tips, or has seen the issue before.

SpoilerShow

mintyPi_2.0_LCD_Board.jpg (1.75 MiB) Viewed 4738 times

also doube check continuity between the test pads on the PCB and the test pads on the screen board. You can even test the continuity all the way to the screen itself. (18 pin connections)

[sygyzy]

Ok, so just to make sure, I think we are talking about the same board. The picture you posted is exactly the screen I have. Where are you saying I should reflow the solder? From the ribbon on the right? The connector on the bottom? I wonder if this is related to the ground issue that Helder posted before (too low of a voltage flowing due to bad ground).

[rodocop]

ground could be an issue, I typically run a jumper wire from the ground gpio to a test pad, I have never been able to get a reliable ground connection on any minty pi, and yes I was talking about reflowing the area where the screen connects to the board on the right side.

[sygyzy]

I already have a ground wire run from the GPIO to the tests pad; I was talking about the ground here - https://sudomod.com/forum/viewtopic.php?f=34&t=3504

Do you have any instructions or links where the reflowing is explained for the connection on the right? I haven't seen it mentioned.

Thank you for your help.

[rodocop]

Literally just brush your hot iron across it. That's usually enough to re flow.

And I haven't tried that fix you linked. But it can't hurt to try everything!

[dryja123]

I wouldn't sweep your iron across the screen ribbon, you could short something out. Could you take a good close up picture of the screen ribbon? I too ran into an issue with a pre-soldered screen and there was one leg on the lcd ribbon that had a broken connection.

[sygyzy]

Hmm I ran a wire from the ground pad and the ground pin (2nd from left) like in this link https://sudomod.com/forum/viewtopic.php?f=34&t=3504 and it didn't help. I feel like I am walking on eggshells trying to balance the perfect angle of the screen to the case. I tried running it with the board/controls sitting on top of the case, inside it, with the lid flat (removed the hinge, etc). I can't see anything loose or anything that would flex or break with me moving the screen. It's so frustrating. Here's a picture of the soldered ribbon. I've had Kapton tape on this the whole time and removed it for the photos.

Album page - https://imgur.com/a/f7uzs