LCD not working
  • So I got my boards and soldered everything together, everything works, sound is good but LCD is dead. I’ve checked over my solder joints many times. All I get is one bright line and one dim line. I’ve tried another LCD I had laying around with no change either. Any ideas?

  • Did you trim the resistor like in step 13?

  • Yeah I’m 99% sure it’s not a contrast thing.

  • Next; Check the Trimmer if there are bad soldering joints.

  • Besides the LCD do the LEDs and switches seem to operate correctly?

  • Have a look at the PCB layout and check the continuity between each CPU pin and each LCD pin. Check for unwanted shorts between pins of the LCD module. Could it be a bent CPU pin that is not fitting well in the socket?

  • Yeah I’ll have to go though the pins and check connection. The switches seem to work fine and I get sound, so it seems fine except the lcd

  • There seems to be a bad (or fragile?) lot of ATMega644p in the last batch of kits, so if you have reasons to believe the chip is damaged, please return it to me, I’ll check it and send you a replacement if there is any problem with it.

  • Heh I’d love to, but too bad I self sourced this. Yeah I can’t understand this one, I even reburned the firmware. I get nice sound so obviously it’s working. I’m going to order a second 644p and see what happens.

    on a side note removing a LCD with quickchip isn’t fun :P

    If I were to place the 644p in a breadboard and just wired up the LCD it should boot and show up correct? Just thinking if anything else besides the crystal is needed.

  • Also the Digi-Key part for the male 1x8 header listed on the Digital board build page is incorrect (3M9330-ND)

    I’d imagine it should be something like this one: 3M9452-ND

    The listed one is the wrong pitch.

  • Thanks, I have updated the BOM with your suggestion. Yes, if you breadboard the MCU, the crystal + caps, the LCD, and ground the first 4 ADC pins it should boot. If you do not ground the ADC pin you’ll see a lot of garbage on screen since it’ll read noise for the 4 pots.

  • OK cool I’ll test it out that way when I get home.

  • I have the same problem :/. Everything works fine (sound, LEDS) except for the LCD, who only shows a white line in the upper row. I've double checked all connections, tried changing the contrast and also unmounted the ATMega644p and no broken/bended pins so i dont know what to check... suggestions?
  • I had both times problems (cold soldering joint) with the TrimmerPot, maybe check this.

  • @Youmakeme: have you also sourced the parts yourself or is it a LCD module from the kit?

    Maybe the extra tests Starfire will do on a breadboard will shed some light about what’s going on here.

  • It's from the kit (2nd batch). Now i'm having fun trying to figure out how the synth works without any visual help so it's not a big deal to wait for the tests.
  • Ok, i was looking through the patches and suddenly the LCD started to show strange symbols instead of the white blocks. They are most of the time "
  • The LCD will show strange patterns if it “misses” the configuration data the MCU sends at boot time. For example, if there’s a weak connection between the board and the LCD during boot, the LCD won’t receive the initial configuration sequence and will be unable to interpret correctly the data sent to it.

    Check the continuity between all the MCU pins and the LCD pins, by referring on the traces image here:

  • Well the mystery continues! I got home and started testing pins from the chip to the LCD didn’t find any not working, so tried the LCD again and it worked! I have no idea on this one. I did nothing but test the continutiy of the traces and it magicly starts working, now it’s working ever since.

    On a side note how do I go about getting all the defualt patches?

  • Play this syx / mid file into the Shruthi (with at least 150ms between blocks) to restore the 80 factory patches

  • And more odd happenings. I played in the syx file and it loads the first 16 but everything after is named ?acon and sounds identical to patch 16 Bacon.

    Also This one really confuses me. My encoder works backwards. If you click down it will increment a patch and if I turn the knob it will change between browse and save, how could that even happen?

  • Looks like the Digi-key encoder pinout is backwards. I rigged it to work now, but definitly change that part out.

    Looks like this encoder would work (CT3011-ND), surprised that one is opposite.

  • First time I hear about an alternative pinout for encoder! BOM is fixed.

    If the patches 16-80 do not load, there’s a problem with the I2C eeprom (the patches up to 16 are saved straight in the AVR). Which reference did you use?

  • So...I checked the continuity, all OK. Power the Shruthi and... Mutable Instruments shows up in the LCD. I tried the different menu pages and clutter started to accumulate in the screen. I restarted it (power off and on) and only the white upper line in the LCD showed up. Re-check continuity and all ok again, so I turned on and the LCD worked but with the same clutter...Any ideas?
  • Yeah that’s odd about the pinout.

    This is the eeprom I used:

  • 400kHz… should be fine… Have you observed any crash when doing the MIDI dump (eeproms which are too slow may freeze). Do you see the ? for all memory slots or are there still a few in the lot that are correctly installed?

  • Yeah there all named ‘?acon’ It seems like I can save a patch to it though. I ran the syx in extra slow to be sure, maybe I’ll just see if I can find the 128k version but no crashes with this one.

  • Do you see the LEDs lighting one by one like a progress bar when you download the .syx?

  • It does but it changes partway though. It will from solid leds, to ones that just blink on and off for a sec as it progresses, if that makes sense. Just as a side note I had to slow it down to about 250ms to get it to load the first 16 correctly otherwise there was errors.

  • Yes, it’s normal, writes to the internal eeprom take longer than write to the I2C eeprom – so they are on for a longer amount of time during the first stage.

  • Hmm OK I have 2 of the eeproms and both behaved the same way. Maybe I’m missing a solder problem I checked but I’ll check again.

  • Well I posted a vid of the unit working, just messing with settings, but if you go to about the 7min mark you can see the banks above 16, and my wire jumper fix for the encoder.

  • My LCD is magically fixed, didn't do nothing and suddenly started to work everytime i powered up :\
  • That’s kinda what happened to me. Also I found I had a 256k eeprom at home and plugged it in and it works fine. It’s a microchip brand, same pinout and speed as the other which is a On semiconductors brand but didn’t work. So I’m working 100% now :D

  • These are the Shruthis self healing capabilities….

  • @Starfire: congrats, I’ve seen your video on matrixsynth. Owning a Shruthi looks like a sure way of getting on Matrixsynth :)

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