No LCD Readout on Ambika

I’ve completed the Ambika motherboard, and it seems to work fine - except there is no readout on the LCD. The backlight is lit, but there is no data on the screen. The LEDs are lit up and change the way I expect them to when I press the switches, so the brain seems to be working.

Its an Optrex LCD and I’m using a 100 Ohm resistor, so that’s not the issue.

One thing I also noticed, this might be hint: when I turn the contrast trim pot, it doesn’t do much, except for when I turn it all the way in one direction, in which case the top half of the LCD lights up really bright. Very odd. Also, the backlight seems pretty dim in general. Maybe I should use a slightly lower value than 100 Ohm?

Some suggestions for debugging would be appreciated.

I partly see the answer on the right of the picture: your solder joints for the MCU pins are very weak. Add more solder everywhere…

Thanks, pichenettes. I’ll add some solder to those joints and report back.

Make the soldered joints look more like this:

Went over all the MCU joints and tt works now!

Thanks for the tips guys. I’ll work on my solder technique :slight_smile: