Shuthi XT : Value 128

Let me wrap this up:
With the filter board disconnected and all ICs removed from their sockets, you have a short between +5V and GND?

I don’t think it is due to a component failure. To my knowledge, the only components that create a short in the event of a failure are ceramic capacitors (that happens under rare conditions, e.g. when their voltage limits are exceeded or when they are under physical stress - but I’ve never seen this happen)

My best bet is that there’s a soldering problem somwhere. Your soldering looks okay-ish but some joints might be problematic. They should look like this. That may already fix your issue. If not, look along all the areas where there is a +5V trace on the pcb. Check on this image:

If you have a very good multimeter, you may also try to measure the resistance between +5V and GND on multiple places on the board. I’ve had a short on a pcb and was able to locate the rough area by checking where on the board the resistance is lowest. Beware that this resistance is going to be super low, so maybe your multimeter won’t be able to measure it.

So after checking, the RNs were on the wrong side (didn’t check like a complete idiot).
I am now able to get the LCD (blank but still) and the can go in bootloader mode.
However, after uploading the firmware through C6, the Shruthi starts blinking all of the LEDs in a random pattern on start-up and the LCD stays blank.
I corrupted something, didn’t I?

LCD blank sounds odd. It should have something on it, or it should be uninitialized, in which case it will have one row filled with all-black (or all white) pixels.
Try adjusting the contrast trimmer, until it shows something

Good call! I’m indeed getting something on the screen.
However, it just goes spastic. I switched to Full Control XT but to no avail. The LEDs goes in a random pattern and it seems to show something around the enveloppe/LFO on the LCD. Defect IC?

There are two XT modes (one for the new XT, one for the original, old XT). Did you try both?
Otherwise I’d check the multiplexer chips and the shift registers on the mainboard.

Tried both mode, same result.
Interestingly enough, multiplexer is not it. Removed all the ICs, replaced them one by one as I had extras.
Even with only the Atmega, the EEPROM seated, I’m getting the same LCD crazyness. Sounds like a corrupt Atmega. I’ll try to send the firmware once again through C6. I’m thinking that maybe a .hex compiled with the right version might solve it.
What version of GCC was it compiled on? 4.1? I can probably go in my Linux partition, build it with this environment, get the hex and send it on Windows (as, for some reason, my Windows AVRdude is the only that works)

EDIT : NEVERMIND THAT.
A bit of resoldering around the RN I replaced and it’s good now.
Thanks man. You were really helpful.

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Hello everyone, sorry for the thread necromancy.
I put this project on the ice for a while worklng on a show. Now that I have more time to spend on it, I fired it up again to find myself with another issue (that never stops)

It seems like the values potentiometer act weirdly. The 4 in the middle can only go up to 3 or 8 instead of 64 or 127. The LFO2 rate flashes values between 126 and 127. The moment I bring the pot down to 0, it is fine though.

Any ideas of what could be the reason why?

Thanks!
-A