New build help: 4.3.3 blank LCD, thermocouple wandering, port 3 wandering

New build help: 4.3.3 blank LCD & port 3 wandering

Hi everyone.

I just finished my 4.3.3. I am a previously proud owner of the 4.2 but it finally bit the dust.

After initially booting with the Rpi (3), the LCD lit up but no text is discernable. Yes, I've played with the contrast dial...to no avail. Note that I have not installed the LEDs yet as I have not printed a case for it yet.

I can log into the HM's web server to view the data without issue.

Port 3 seems to be wandering all over the place (+/-400 degrees). Ports 1 and 2 seem to work fine.

Any suggestions on what to look for?

Also, the 5V converter seems to get really hot to the touch. Is that normal?

Thanks!

John

JohnS said:

Hi everyone.

I just finished my 4.3.3. I am a previously proud owner of the 4.2 but it finally bit the dust.

After initially booting with the Rpi (3), the LCD lit up but no text is discernable. Yes, I've played with the contrast dial...to no avail. Note that I have not installed the LEDs yet as I have not printed a case for it yet.

I can log into the HM's web server to view the data without issue.

Port 3 seems to be wandering all over the place (+/-400 degrees). Ports 1 and 2 seem to work fine.

Any suggestions on what to look for?

Also, the 5V converter seems to get really hot to the touch. Is that normal?

Thanks!

John

Click to expand...

Ok so the port 3 mystery deepens. If I plug in my thermocouple it settles down. Only thing is, there is no probe in the port. It shows a temp close to the thermocouple temp and stays fairly steady. If I unplugged the thermocouple it goes crazy again...

On to the LCD. I ordered two kits so I built the second kit's display. Success! The display shows the info but the buttons are unresponsive. Sigh!

Pics of the display not displaying



Pics of the other display working but disabled buttons

There's so much going on here I'm not sure what to suggest. It is definitely a step in the right direction to have a working display! The buttons are a very simple circuit so that's probably the easiest thing to start with.

The #1 most common problem here is that there's a bad GND connection on the 1k resistor on the top right of the base board. You see it here next to the right pinheader riser 5V signal. Check both connections on that 1k resistor. One end connects to BTN on the atmega, the other to GND.



If that's good (it wouldn't hurt to hit them with the soldering iron too) then put power up everything with the LCD/button board attached and measure the voltage on the BTN pin on the right header. Should be 0V. Now press and hold one of the buttons and you should see voltage. Each button has a different voltage when held. If you're seeing voltage there, you've got a bad connection somewhere between the riser and that 1k resistor. If no voltage changes, eeeerrrrr then I am not sure!

You will probably want to put a piece of non conductive tape over the top of the USB shields on your Pi while you're working on this. Without the LCD in a case and probing around on it, you can bend the assembly so the LCD touches the USB ports and possibly cause bad news.

Here's the voltages layout for the LCD/Button board too if that helps.