Xt build problem

just finished building xt everything’s working and sounds great, but when i change parameters i get strange characters appearing on the lcd. any ideas ?

Maybe a weak solder joint on the OLED?

will re- solder and check.
Many thanks

Or a bent pin on the ATMega, or a bad solder joint on its socket…

now i get just white blocks along the top row using lcd not oled by the way

So let me get this straight, you have tuned the contrast trimmer, so you can see what’s going on, until you change parameters?

sorry sorted lcd was problem pulled a couple of solder pads up fixed it with jumper wires using the pdf schematics as a guide. not as pretty as it was but sounds just as good. thanks for the responses