digital control board leds burning and blocks on lcd [SOLVED]
  • i’m building 2 4pm’s … one of the digital boards has a problem.

    it has led 1 3 5 and 7 burning and shows a row of blocks on the top row of the screen.
    it was ok before I soldered the display… or I might have shorted something while turning the trimmer of the LCD.
    both filter boards work fine with the working digital board

  • Awww, not again :( Check the soldering of the switch, the resistor network, and the 165, but there’s a good chance you have shorted some pads of the digital board with the metallic part of the regulators downstairs, causing the destruction of the 165.

  • ok.. I think that’s what happened
    could i check by changing the 165 of the other board? or would I destroy even more?
    this happened while testing the digital board the same way it shows in the picture of the digital board building guide .. maybe you can change the picture with the boards connected without the spacers to a picture with spacers. then it won’t happen that quick.

  • Is there any chance to force people to read the FAQ before asking a question . . . ;-)

  • I think I probably read the FAQ a long time ago…

  • FWIW, it would probably throw me too. I’m used to having some headroom above the regulators… Maybe it makes sense to include a small piece of plastic that can be somehow attached to the bottom of the control board in that quadrant? It would avoid all of these LED barbecues.

    Maybe a piece of plastic the same size as the boards with holes for the screws?

  • I’m always tempted to do some “Präszisionslasergeschnittene” (as my sons would State) Paper Covers for this…

  • I had read this thread with this shortcut earlier and was very careful while handling the PM4 boards. I am quite sure I would have made the same mistake if I had not been warned. So maybe it would be a good idea to include a little warning in the Step 11 paragraph at least, no?

  • Or paper. Cardboard from the box…

  • I found a simple solution while testing the second board. Just bend the regulators outwards. And…. Don’t test it late at night being very tired from a long days work.

    second problem is my filter boards don’t work. it worked for a short time and then just hum and buzz. the vca seems to work though. the digital audio signal is present on the digital board. checked all soldering and resistors on filter board… where to look next?

  • The 4 points mentioned in the assembly notes?

  • sorry for asking stupid questions… I justed hoped somebody would say, o just do this.

    signal present at 1 and 2 with hum .. no signal at 3 and 4.
    also doen’t respond to changing cutoff at these points. should it?

  • it’s the same with both filter boards so I think I did something wrong on both .. or the fault is on the digital board I’m using.

  • What kind of signal do you get on the OSC> pin of the control board? Which voltage do you get at the F> pin of the control board when you sweep cutoff from 0 to 127 after having played a C4? What about the voltage on pin 7 of IC2?

  • Solved!
    resoldered the connections between the boards on the digital board and now both filter boards work!
    optically they looked fine .. but they were not.
    thanks for helping out!

  • replaced the 165 and it’s working again! thanks!