Build finished - no sound at OH, CH, CY and PC2

  • gihaume wrote:Do you have an AC mode on your multimeter ? If yes, what does it say ?
    Cheers for responding this quickly. The new power adaptor has arrived and the same thing is happening, so it’s obviously not the one to blame. At +15V output I get over 18V measurement and rising, at -15V only 0.83 :(
  • Hey Ambicumber,

    did you get any closer to a solution yet?

    good luck!
  • Hey m8. unfortunately still not. Will post any progress here for others to see, if this happens :D
  • ambicumber,

    First you have to disconnect power supply from the IO board to the mainboard.
    1/Could you confirm that your wall wart PSU is a 15VAC at least 600mA ?
    2/Then test +15V, +5V and -15V with your MultiMeter in DC mode, what are the result ?
    3/Check that D109, D110, D11, D104 and D94 to D97 are in the right way ?

    Then let me know.
    Best regards,
    e-licktronic
  • Thank you Vincent for helping me out!
    e-licktronic wrote:ambicumber,

    First you have to disconnect power supply from the IO board to the mainboard.
    1/Could you confirm that your wall wart PSU is a 15VAC at least 600mA ?
    I confirm that, even bought a new one during troubleshooting so I have two.
    2/Then test +15V, +5V and -15V with your MultiMeter in DC mode, what are the result ?
    (Edited here because I changed the multimeter!)

    +15V = 15.20 V
    -15V = -18.20 V and fluctuating at J8
    Pin 3 at J10 = 4.70 V
    Pin 7 and 8 at J10 = 4.97 V

    3/Check that D109, D110, D11, D104 and D94 to D97 are in the right way ?

    Then let me know.
    All are put in the right way.
  • OK, update here:

    As Vincent instructed, I replaced the REG2 again and got stable voltages as follows:

    15 V = 15.19 V
    -15 V = -15.19 V
    5 V = 4.98 V

    I have now connected the mainboard to the PSU board. Now the mainboard problem is as previously stated in this forum thread:

    I have no cymbal sound (CH, OH, CY and also PC2) both on individual and mono outputs. Also, clap sounds a bit weird - it is very quiet, dim, and seems to lack the crispyness. Accent seems to have no effect on sound, and I don’t hear any difference in handclap when rotating TM3.

    Will update until the issue is resolved ;)
    Last edited by ambicumber on Mar 10th, '19, 02:59, edited 1 time in total.
  • I have replaced U3, but that didn't help. Upon scoping the cymbal noise section I found that the hex inverter (U4) has good square wave noise output at pins 2, 4, 6, 8, 10 and 12 looking like this:

    Image

    At pins 1, 3, 5, 7, 9, 11 and 13 I get this which is also probably fine:

    Image

    Can you confirm these t-bridge outputs at U3? This is the output of U3 (4558) pin 1:

    Image

    And this is the output of U3 at pin 7:

    Image

    Any idea what I should troubleshoot next?
  • After modding a speaker, I can clearly hear the square waves at hex inverter U4, however, at the outputs of U3 there is only very faint noise. Changed a couple of 4558s and even TL072 but no change.