Circuit Gem no video/blank screen

[brettlands]

Hey everyone!

Just got my Circuit Gem and I'm super excited to put everything together. Soldered the pi to the board and everything went smoothly. I checked all GPIO pins with the test pads and everything seems to be OK. When I try to boot up, however, I don't see anything on the LCD. The LCD flickers once shortly after turning it on, but no image ever appears. Safe and emergency shutdown seems to work as I can flip the switch to OFF and then press mode to shut down immediately.

Any ideas? Really appreciate everyone's time and assistance. Thanks!

[brettlands]

Image here for reference:

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[kite]

So the PGOOD LED is on, meaning the PI has booted! However nothing on screen..

Can you check your solder points that are in purple/pink on this diagram (press > to expand the image): https://github.com/kiteretro/Circuit-Ge ... successful

You can use a multimeter in continuity mode to probe the labelled test pads to see exactly which one it is ... or just re-solder (re-work, do not try and remove the Pi) the purple pins

[brettlands]

So the PGOOD LED is on, meaning the PI has booted! However nothing on screen..

Can you check your solder points that are in purple/pink on this diagram (press > to expand the image): https://github.com/kiteretro/Circuit-Ge ... successful

You can use a multimeter in continuity mode to probe the labelled test pads to see exactly which one it is ... or just re-solder (re-work, do not try and remove the Pi) the purple pins

Thanks for your reply!!

Double-checked continuity of all of the solder points using a multimeter and everything matched up except: GPIO 16 / K-BATT MON

When I tested for continuity between GPIO 16 and pad K, I got nothing. I tried re-soldering but that didn't fix it. I did notice something very strange, however:

The multimeter beeps when I touch GPIO 16 and M-LCD FMARK. After noticing this, I decided to test continuity between GPIO 16 and 18 (18 is supposed to be connected to pad M). Surely enough, 16 and 18 do indeed register as connected.

Am I out of luck? I'm almost positive this is what's causing my no video issue since pad M has to do with the LCD, and for some reason it got connected to GPIO 16 (not even sure how this could have happened). Really hope there might be a fix but I'm thinking there probably isn't since removing the Pi from the Gem is not possible. Really bummed that I just missed the flash sale too, if I had discovered this 48 hrs sooner I would have ordered a new board.

Regardless, if anyone has any ideas, I would really appreciate it! Thanks so much

Additional pictures for reference:

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Front

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Back

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[SparkySid]

... notice something very strange, however:

The multimeter beeps when I touch GPIO 16 and M-LCD FMARK. After noticing this, I decided to test continuity between GPIO 16 and 18 (18 is supposed to be connected to pad M). Surely enough, 16 and 18 do indeed register as connected.

Regardless, if anyone has any ideas, I would really appreciate it! Thanks so much

I'd say you've successfully found the problem, now comes the challenge for a fix. I'd personally start with some solder wick and/or a solder sucker. I went through quite a bit of solder wick last night removing the USB and HDMI connectors and it did a good job pulling the solder out of the vias. I suspect if you put the solder wick on pins 16 and 18 at the same time that you will remove the solder bridge. Perhaps just in case, continuity check all of the soldered adjacent pins to ensure there are no other solder bridges.

[kite]

Yeah that could be an issue, FMARK isn't actually used however it is still connected to the LCD 'FMARK' pin which i'm not sure exactly how it behaves but likely is causing some issue.

Could you check continuity between some of the other LCD pins nearby?

[brettlands]

Successfully removed the bridge between 16 and 18! GPIO 16 is now only connected to K. 18 is connected to M.

Still no video when I boot it up though :/

There were no other bridges in the area. All of the LCD pins nearby are connected to the correct GPIO pins. Still trying to figure out what else is going wrong here...

[kite]

hm, the little flicker is the pi booting and 'resetting' the LCD (and backlight) and is where it would show the K logo while booting up.. at this point it may be best to email me and we'll sort out returning it to me for debug/repair and maybe i can shed some light on it (because it's the first time releasing it, any problems like this i'm not sure on the cause other than improper solder so probably best i have a poke around)