New Heatermeter build: LCD lights up, with no text


 
J

JasonJoseph

New member
I have a new 4.3 build on a rp 2. First boot up, everything appeared to test fine.
Once in the case, I noticed the green LED would flicker when tapping case.

I pulled it apart, and double checked LED solder point, and all seemed fine.

Re-assembled case and powered up. Now LCD display lights up, with no text. I have tweaked the potentiometer and still no text.

I'm at a loss on what happened.

Any advice would be greatly appreciated!

--Jason
 
Both the green LED and the LCD text are output by the shift register on the LCD/Button board so it seems like a likely culprit. The green LED is the top left pin looking from the top and LCD text comes out the remaining pins on that row (apart from the top right which is ground). I'd check your solder joints there and also the 5V power to the chip to make sure you're getting good contact there.
 
Thanks for the quick response Bryan!

Ok, So I have double checked all solder points on LCD connection, and also the 5v.
All lights seem to work fine now, so that helped!

LCD still lights up with no text though.. :(

I am wondering if I need to order another LCD board?

I am going to try my rp 3 and connect to see if everything else is working still.
 
Did the LCD used to work then stop? That's pretty unusual and probably a loose/intermittent connection somewhere. If you have a multimeter, I'd check the continuity between all the lines from the LCD to the shift register, you can see them in red in the image. See if you're getting the 0V with it blinking to some other voltage once every second (when the LCD updates). If it isn't, check the pins on the other side, MOSI, SCK, LCD_CLK to see if they are wiggling. If not, pull off the LCD board and check it on the female headers on the Base board.

It should also be able to drive the LCD without a Pi at all, so you can try that as well which makes it easier to read the voltage on the connections on the base board (flip the whole thing over).
 
I've isolated it to just LCD issue.
I can WiFi into the pi and everything operates as expected. (LED lights, fan adjusts, etc...)
LCD brightness settings go up and down also..

I will grab the multimeter and start testing.

It did work when first assembled. I agree it seems like it should be something loose.

Thanks for the help!
 
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