New Build - LCD & Probe Issue


 
D

Doug McCurry

New member
Hello everyone. Just completed a new build and I'm having a few issues. Most certainly related to my eyes and soldering ability:).

Here is what works:

I can boot and connect on Wifi to the PI and access the graphs and config.
Thermocouple works and seems accurate
Thermister probes 2 & 3 work and seem accurate.

Here is what does not work:
The LCD screen lights up but does not display text. it does respond to pot adjustments.
Thermister probe 1 does not respond.

I have hit the solder joints again and cleaned off the board with alcohol. Same results.

Per a recommendation in a recent post with LCD issues I checked continuity between the shift register IC and the LCD and continuity was good.


Here is a link to pics of my boards:
https://drive.google.com/drive/folders/1QTD0-3xg7E51ut_DnroyyYus9jxFzkcE


Thanks for any help,

Doug
 
From the pics you posted, the solder joints look OK. I'd give the board a good scrubbing with a toothbrush and some isopropyl alcohol.
 
OK, by adding solder to the probe jack connections I now have all probes functioning!

I went over all of the solder joints and cleaned the board and the LCD display still does not display text. Anything I can test with a meter to see where it's going south?
 
I verified voltages 12, 5, & 3.3 are all looking good.

Checked the pins from the microcontroller LCK, MO, SCK pins to the riser header LCD1F. All good.
 
OK, following up. I found the the middle LED was soldered on the board with the wrong polarity. I removed it and changed the polarity and it now works fine. After this I adjusted the LCD pot and I now have text on my display. Everything is working 100%!

I'm not sure that the polarity issue on the LED fixed the LCD. I had also made quite a few solder improvements without adjusting the display pot so it could have been working before the LED issue was discovered.

For others having LCD issues you should know that there is only a small range on the pot where the text will display. Slowly run the pot through its full range after each troubleshooting event.

Now to fabricate a mount for the fan for my XL Egg and do my first "controlled" cook!
 
Hmm, LED... If I recall correctly the one LED is controlled by the ATMega and the other two are controlled by the shift register IC. The shift register also controls the LCD, so there is a possibility a reversed LED2 or LED3 could effect the shift register and make the LCD flake out I would think.
 
Not so sure the LED would make a difference as its basically a diode. Meaning electricity can only flow one way. So if it was in backwards it would not work.
 
You must log in or register to reply here.

 

Back
Top