LCD initialization woes

So feeling nostalgic, I am trying to bring back my original shruthi back to life (I think it’s the third one that was sold to the masses). This thing was used and abused for all sorts of testing, hacking, etc so its in poor shape (lifted traces and whatnot) but I got new parts on to it and it was good to go (working) until I powered it up the other day and the LCD wont initialize (top bar solid boxes). I have checked the connections from the AVR and all those are fine and went as far as pulling the LCD and checking with my plug in one and the problem is definitely on the control board. Input appreciated…

There isnt much between the MCU and the Display. Upper row with blocks means it doesnt initialize correctly but has power. Do check all the Lines between the Display and the MCU (measure directly on the Display PCB + AT-Mega. If thats all OK either the ATMega is defective which would be obvious (LEDs, MIDI IN etc…) or its the Display…

Yeah, went over both those points (tried different display, same results) and check continuity for all pins

Have you tried swapping the ATMega? I once had one who had some dead outputs due to static discharge while in transit…

Yeah, need to try that. The weird thing is that it was working fine, I refurbed the CS, soldered on the LCD, did a quick test and it just sat there for a week before I fired it back up and it was kaput.

:frowning: no dice. Not the AVR. Are there any other pins in play other than the direct connections to the AVR? Everything works fine other than the display (which used to work fine…)

Just out of curiosity, how are you powering it up? Are you pulling the plug in and out of the Shruthi or are you power cycling the wall wart? I am currently trying to suss out an issue where the shruthi does not boot all of the time. I have found that if I power cycle the strip the wall wart is plugged into rather than plugging the power into the shruthi hot, it boots. Otherwise, the display remains blank and the unit doesnt boot. So far I have swapped the atmega with a good one, moved it to a different filter board, tried different adruino headers and the issue follows the board. I’ve even tried a different control board on the same filter and it boots.

it’s the same PSU I use for all my testing and it works fine with all the other shruthis I have on hand atm… worse yet, this worked fine a couple of days ago… I just triple checked the connections with my meter and all the LCD to uC connections check out.

Yeah, my PSU is the same that I use for testing as well. Have you tried power cycling different ways? I’m not sure what this will prove, but it’s the only way I can get mine to initialize. I’m pointing my finger at the OLED itself. You probably have a totally different issue than I.

I’m not even using an OLED in this case, standard 162A type but I’ve switched it with my portable one (female SIL header) and the problem persists so it’s something on the control board for sure

Check continuity to ground for pins 1, 5 and 16 of the LCD and continuity to +5V for pin 2. Also check that you do get +5V into the digital board. And perhaps check the contrast pot - if it’s freaking out you could be seeing solid boxes even though it’s actually displaying the correct characters. Hope all this is true for the original shruthi too, but I think it should be.

Nice, u nailed it. Pin 5 was open (LCD header has been changed at least 3 times on this board) so the through holes are pretty tore up. I checked the connections, not the ground points


Glad it worked