Still a problem in my CLAVE/RIM SECTION

Discuss Yocto construction and related issues
  • it's not a click, it's actually faintly triggering the drum when it shouldn't
    so check your voltages around the rim/clave section which take the individual trigger voltage and combine it (with an AND operation) with the common trigger voltage
    compare those voltage levels to the same place on another drum section which works properly

    and check the components of that circuit (they are two or three transistors with some passives around them), check for anything weird on the PCB, for proper component values and orientation

    also, did the rim/clave on this yocto ever work properly or is it misbehaving like that since it was built?
  • ok.. thanks for the hint!
    first.. the trigger problem was from the beginning when i finshed the yocto.
    is this right when i see in the schematic that the trigger "input" signal comes in at R299.
    and what is the right value? i am not so pro in that :)
  • in the yocto schematic, TRIG is the common trigger signal that "carries" the accent
    yes, for the rimshot - it arives at R299 which is 4k7 (that is electronic-h4x0r-speek for 4.7k Ohms)
    Q60 and the other transistor below it, as well as the passives (resistors) is the structure which performs the "AND" operation on the common trigger and individual instrument trigger or "gate" (which is labeled RS and comes in at R297)
    the result from this structure comes out from Q60 and the 22k resistor
    you'll see this structure present in pretty much all other instrument sections, where the only (i think) difference will be the label of the individual trigger signal, respectively for the concrete drum

    basically, both signals (common TRIG and instrument GATE) sit at some level (maybe 0V) normally
    then, when the sequencer plays - it would pulse out the TRIG signal on every step
    if an instrument GATE is high during the TRIG impulse - the result would be an impulse for that instrument, otherwise no impulse (thus no trigger)
    so, you could check the components around that area of the RS/CL for proper values
    the values in the yocto schematic are not very easy to read, so you might want to check them against the BOM or the build manual
    check for the proper transistors and their orientation, and also inspect the PCB for anything that looks suspicious
    then, you can also try to measure the voltages around the trigger "AND" circuit, and compare them to the equivalent voltages of another instrument which works fine (in same conditions)

    also check the remaining components in the RS/CL section
  • ok.. thanks for the good explanation! :idea:

    is it possible that Q59 or Q60 are damaged? i mean is the problem a sign of a damaged transistor?
    i might have one 733 .. can i use any 2sc945 ? i thik these are standard..
    but first i will measure all the resistors.

    THANKS !!
  • well... tried to solder 2 new transistors (q59 q60)
    absolutly no change ;) i thought there is a chance as it looks like they are responsible for trigger/accent... but no effect, problem stil here!
    the 2sk30 transistor has probably nothing to do with it?!
    the values of the resistors are ok, at least in the section around the trigger input...