Shruti-1 doesn't boot (first test) ...
  • Hello,
    I ordered a Shruti-1 kit and assembled it, but i got the polarity of IC2 and 3 wrong on the control board. After the “first test” check nothing happend and i noticed the mistake. So i desoldered the chips and replaced them with new ones (ordered with article number at, but the shruti does still not boot, or actually do anything at all, no lit leds etc. I measured the voltage on the 5v and GND pins on the board, and they are correct, so it shouldn’t be a power supply problem (while connecting the pins for measurement four leds lit up).
    I didn’t solder much before, so some of the soldering joints look rather bad (especially where i desoldered the ICs), but i don’t see anything that looks like it would cause problems (?).
    I don’t really know where to go next, besides replacing the other parts piece by piece, so any help, ideas etc very much welcome!
    Maybe i’m just missing something obvious?

    2592 x 1944 - 975K
    2592 x 1944 - 972K
  • When you hook up the control board to the filter board, what happens exactly? Do you have LEDs lighting up? Which ones?

  • None of them lights up, no life signs ..

  • Doesn’t seem to be much solder on the header pins.

  • ...and the ground header pin (one up from the bottom) on your second (top view) photo doesn’t seem to be connected at all, as it’s a ‘blob’ of solder that hasn’t flowed onto the circuit board pad beneath it.


  • Chief of staff! It was the grounding pin. LEDs do light up as they should now. Thanks a lot!

  • Glad I could help, and that you’re up and running :-)

    Perhaps Mutable Instruments could use your photo to help other builders – it’s a classic example of a dodgy connection! ;-)


  • I like the mountain and toffee apple analogy myself. Mountain shape being a good joint and a toffee apple shape is a bad one.

  • Status report:
    I soldered the display: works fine (yay!); I get sound in and out the filter board, midi in works (yay!).
    BUT: the buttons only work occasionally, mostly not :/
    It’s a bit wierd cause first time i checked they did work, and then two other times, but usually there is no reaction to key presses.
    I guess the problem is somewhere on the control board too then, any ideas on that?
    Ah, and yes, ofcourse mutable instruments may use my pictures as bad example :)

  • Check all the solder joints on the 74hc165, and on the resistor network.

  • hm, i checked the soldering points and renewed some that didn’t look good.
    there is a scrape on the PCB in between the two most up-right pins of the 74hc165 on the top side, could that be problematic?
    Could i maybe measure the cinnections somehow, looks like the is a connection between all of the left pins of the buttons and the second down-left pin of the 74hc165 (downside view) eg .. ?

  • Check that the upper right pin (pin 16) is at +5V, and that the pin below it (pin 15) is grounded.

  • hm, seems to be correct, and the 74hc595 is grounded on pin 8 and 13?

  • Yes, this is correct.

  • I discovered something pretty wierd by accident today. When i touch the pins of the 74hc165 on the right side, it will throw me into patch save/compare etc menus, after that the buttons do sometimes (not everytime, but often) work as expected for some presses .. after a while the will stop to work again .. any ideas?

  • Simple, don’t touch the pins :)

  • well, then the buttons don’t work at all .. usually :P

  • Did you solder them correctly?
    EDIT: Both the buttons & any and all connections to the 74hcxxx + ATMega ?

  • I don’t see any bad soldering points (doesn’t mean there aint any, but i checked all of them multiple times now). The PCB is somewhat chipped after the desoldering and resoldering, some of the cunducting paths are open at the ICs, but it doesn’t look like they have contact to the soldering points to me (measured that also).
    I think of ordering a new PCB and rebuilding the control board from scratch.

  • That will look cleaner/neater as well :)
    If you check each connection, and don’t see any faults, you might want to reheat them with a soldering iron anyhow, since the pins could still contain faults :(

  • It’s possible the pads have separated from the tracks. Check the pads connect to the appropriate pins on the ATMega.

  • Also sounds like the resistor network isn’t doing its job properly if you can generate phantom keystrokes by touching the 74hc165-can you check that you have the resistor network oriented the right way?

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