VCO making a nonstop drone on a fresh build ( builder error , solved!)
  • Hello everyone! I just finished my anushri and was confident that i was home free but it turns out i was not.
    I did the voltage check and it was all good. The problem is the vco is making a constant drone. On the next phase of troubleshooting
    Voltage vco of the gave a continuous reading. Thats all i the info i have so far.

  • If you have a constant drone than the problem would be with your VCA. Does the filter work?

  • > Voltage vco of the gave a continuous reading

    Could you clarify which point you have measured, and which voltage you get?

  • Yes the filter works great. I will get back to the testing and come back with some more specific information. Thank you for the quick help too! Also i thought it was the filter too but when you turn the osc freq. pot you clearly hear it raise and lower.

  • Ok… I tested a constant 1.9 volts dc with the test lead on the “a” spot marked vco and the ground pad two spots over.

  • 1.63 vdc….. Oops.

  • among the 6 LEDs, which ones are lit?

    I’m suspecting something forces the “hold” function on…

  • In synth mode top left led in the horizontal row in sync with the lfo and and the vertical row top left of synth switch. Each switch responds correctly with the led to the left of the left row. When i try the hold function the 2 top left become light up dimmer with lfo response on the left. I hope this makes sense.

  • Yes this makes sense… but we have to understand why the DAC is stuck at 1.9V. Maybe a solder bridge somewhere? Do you have a picture of your assembled board?

  • Photo of board.

    image.jpg
    1970 x 1210 - 753K
  • I do not see any solder bridges after checking multiple times. Been hoping to find a mistake but nothing i can see visually. Need a photo of the top?

  • You missed 4 solders on the top right

  • Here you go , I dont know if they are the reason, but they cant help :)

    missed.jpg
    1970 x 1210 - 334K
  • Haha…thank you…i needed some else to check. Wtf? Welcome to the assembly of electronics i guess. I will solder em now and let you know.

  • Yes! That was it . Great catch man thank you. It appears my problem is fixed. Off to a quick introductory jam… Thanks again mutable community!!! Thanks Oliver for making rad musical instruments. So far the shruthi is a keeper!

  • No problem . Im no expert ,Im the guy that put chips in backwards…..TWICE :)

    but I can sure look at pics :P

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