Blank screen or one line only

[BenoitCaron]

Hi, this is the second HW5 I'm assembling. The first one works fine, but this one doesn't.

Firmware 12.8 beta (red display)

• when started without an SD card, the screen displays "SD Error" as expected, but the the text slowly fades away (not shown on video)
• when started with an SD card (correctly configured), the screen briefly shows a row of pixels, then nothing. Once did I manage to have a single line of text showing ("Game boy"), but even then the bottom of the text was truncated.

Firmware 12.4 (green display):

• when started without an SD card, the screen goes full green
• with the SD card, same as above

Is my screen defective? I'm pretty sure I followed instructions to the letter, + my soldering doesn't seem bad :/

https://github.com/sanni/cartreader/assets/5237965/57268ce8-2fe7-4593-bfcc-f0d70a47cf39

https://github.com/sanni/cartreader/assets/5237965/da9552e2-79ea-4fc8-bbaf-a481c8cb4ed6

https://github.com/sanni/cartreader/assets/5237965/561369b6-04ea-447c-ab1f-cc5f5ac9758c

https://github.com/sanni/cartreader/assets/5237965/66e48d40-732a-40e6-b33d-fb2a290844a0

[sanni]

Looks like a short circuit somewhere near the SD slot. MOSI and SCK seem to be the only pins shared between the LCD and the SD card according to the schematics of the lcd module, so I would start there.

[BenoitCaron]

So these two points? They're not shorted :(

[Ancyker]

Are these pinn actually soldered?

[BenoitCaron]

Yes, they are.

[BenoitCaron]

Well my return window was closing so I returned the display and ordered a new one. I'll close this issue for now and will update it when the new display arrives.

[BenoitCaron]

Follow-up: received my new screen and it now works as expected, no changes whatsoever to the main board. First screen was defective. Thank you all for your help!