Damaged Avr?

hi agin. Can anyone tell me how i can see if my avr is damaged? My LCD is acting strange, so I checked for shorts between the pins that connect it, and there is continuity between some of them. Im not sure that is normal. In the trouble shooting guide it says to check the continuity between the pins of the MCU that are connected to the LCD. I’m not sure what the MCU is so if someone can help me that would be great.
I have disconnected the lcd and taken out the connecting pins.

there is also continuity between some of the pins in the ATMEGA . Not sure if that is normal.

MCU = ATMega. If you examine the schematic you will see which pins from the ATMega are directly connected to pins of the LCD. If you test between the pin on the ATMega socket and the corresponding pin on the LCD you should have continuity.

Also, please tell us what “My LCD is acting strange” means exactly!

Yes there is continuity between the appropriate AtMega and the connecting pins of the LCD. when I say strange, I mean not all the squares are lit. I have adjusted the contrast.

Could you post a picture?

this is with the LCD disconnected and just held in place. You can see that not all the squares are lit up. When it was soldered, only these squares were lit but i could still make out some lettering.

your leds seem to behave normally, so I’d rather bet about a badly connected screen.
First try to see if the buttons react OK, if it responds to midi and if you can get sound out of the shruthi. If it’s ok, then it means that it’s very, very unlikely that your ATMega chips is damaged.

I don’t see much solder on the LCD pins…

There is no solder because i desoldered it. I will try to re solder it now and see what happens. The buttons seem to respond but no sound when connected to midi. I will see if re soldering helps

Resoldering the screen won’t help if you’re not getting any sound, it may annoy you when trying to fix your build.
It’s specified in the build instructions that it’s clever to perform a soundtest before proceeding to soldering the screen. Do you get the test tone (hold S1 for 2s)?

I wasnt sure how to do that. I’m new to all of this. Is S1 the first switch ?

Yes I get a test tone. Excuse my ignorance

There’s no problem, but I think you would have used your time a bit better by reading the building instructions more in details. Nothing harmful.

So your filter board is ok, but you seem not to receive midi :

  1. Are you sure your midi keyboard is set on midi channel #1 (the one used by default by the shruthi)?
  2. are you sure your 6n137 is oriented properly (subsidiary question : you don’t have it swapped with the 24LC chip, right?)?
  3. No weak solder joint around the 6n137 socket? Diode oriented well?

If you’re finally receiving midi, then you can check the solder joints of your atmega, and if everything looks perfectly right then you can solder the screen.

And check the soldering of the MIDI connectors, i got fooled by a weak solder joint which looked good at first look and worked before it failed. A good advise is to measure the connectors for continuity to the PCB before mounting the LCD. Desoldering the LCD panel really sucks (from my own experience…)

i get midi, I re soldered some of the joints on the atmega. All chips are in the right spot and oriented correctly. I can play one sound through midi. And I re soldered the LCD, Same thing. Only one sound and can’t scroll through different sounds. The display still looks like it does in the pic.

you have a probably a joint between 2 pads, maybe around the MCU. I’m afraid you’ll have to desolder the screen once again to solve this issue. Wait for a suggestion from pichenettes, though.

ok thanks for your help