BD/SD no output

Discuss Yocto construction and related issues
  • I "finished" my build but there are a lot of problems. Oh well. :oops: On the Bass drum, I incorrectly stuffed R166 and R173 with 68K resistors instead of 6K8. I have now changed them but there is still no sound. I have re-checked all the components again and checked for bad joints. I wonder if I have fried something due to incorrect voltages. I checked the schem and Q44 is near R173. Also Q43 is near R166. Does anyone know if these are easily damaged? I am trying to avoid desoldering everything randomly, haha. Thanks for any suggestions.

    PS - snare drum outputs but the noise does not get mixed in. Will look at that later.
  • Dear Snoozr,

    First download schematics, then check all power supply and ground points in the BD section
    With a scope or soundcard scope, check trigger signal at Q40 and Q39 base.
    Still with the scope have a look on Pin 1 and 6 of U12 if signal is present.

    I think it s a good start

    Best regards,
    e-licktronic
    Best regards,
    e-licktronic
  • Yayyy, this was a great start! I checked Q39 and Q40 - this revealed Q39 was dead. Replaced it and I am getting sound. Merci beaucoup! Now on to the next problem :D
  • VR5 on my Bass drum does not seem to affect the sound at all. It seems to be soldered fine so I wonder whether something else might be damaged. I tried to read the schematic and it looks (to me) like Q43 might be involved in the sound. Also Q43 is the same value of transistor as my dead Q39. Does this seem like a good candidate for replacing or should I keep looking? Thanks.
  • Try to have a look on bad solder on your bassdrum. Remake all solder sometime fixed the problem.

    Best regards,
    e-licktronic
    Best regards,
    e-licktronic
  • Thank you, this solved the problem :D
  • I have a few more things to finish up on my build but even already it sounds great!

    #1 The Clap/maraca does make sound at the individual out but not to the master out. The schematic is clear about the path to the individual out (CP_MA_OUT), but I can't figure out the path to the Master out.
    #2 The Clap has too much reverb and adjusting TM3 does nothing. I read the service manual and it says Q70 (and possibly Q71 and Q72) are involved. However the service manual has a long, confusing explanation of what is going on. Maybe someone can help me narrow it down? I reflowed all the joints on this section.
  • Problem one is due to a cold joint at that jack socket for the clap and maracas and R7, or the switch don't work well.

    These jack socket have a switch. So when you put a jack cable in it, the contact is broken and the signal comes out of that individual jack instead of going back to the Master section where all instuments get combined and get send back to the Master output jack.
  • Thanks Ikke, great tip! I will try that soon.

    Today I was testing Q70 and I get white noise at the emitter (??) and reverby clap signal at the base and collector. (I don't know anything about transistors but I would think the white noise would be somewhere else besides the emitter since it is the "input" to the envelope.) Q70 is inserted correctly though. I also checked R348, R349, and R200', and they are all stuffed correctly.