Ad Widget

Collapse

Announcement

Collapse
No announcement yet.

Boss DD-3 Problem

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Boss DD-3 Problem

    Started on another forum, posting here because the other forum doesnt seem very active.

    Schematic: https://www.badcaps.net/filedata/fetch?id=2255465
    Video:https://youtu.be/HrLFl7cKsnM


    Pink label Square chip made in Taiwan. Bypass works, direct out works. Delay signal is not right. Another person described it as " constant a noise that can be clearly shaped by Delay Time, Volume and Mode, but very subtle by Feedback" Clock seems to be working. I replaced all 10uf electrolytics just because. No change. Based on sound and experience, should I be looking at the AD part or the DA part? I found a breakdown of how the microcontroller samples 12bit audio, I have a scope, I plan on doing more probing.


    Update 1:

    I pulled C049 to help isolate the problem, and that killed the ticking garbage noise but no delay (obviously). So I used the tone probe back to IC8. I am not sure how the whole DA thing is accomplished but I know it's done by RA1 and IC8b. Looking before IC7, pin 3 of IC5 has clean signal. If I understand correctly, pin 7 of IC5 should be serial pulses, which it seems to be. So now I'm wondering if its a problem with RA1 and IC8b or if theres a problem with the micro controller. For shiggles I checked the adjustment of the clock as shown in the documentation and it says the pulse should be 5v and 12.5us rising edge to rising edge. I only had the cheap chineasieum scope today, the clock signal is present but it was only reading .5v P-P. I double checked all the voltage rails and everything is close enough 8.8v 4.2v and 4.8v. I'm sure the battery is weak after all the troubleshooting. I checked the memory chip and there is clean serial bitstream on the scope. another thought I had was the compander. Is all the noise "normal" and the compander removes it in normal conditions? I checked the tants attached to IC2 and both check good, usually they let the smoke out so Im not surprised that they test fine.

    Lots of testing and no real progress.

    I apologize for the scattered thoughts. My brain is a series of Robot Chicken Sketches.

    Tomorrow I am going to break out the Tektronix if I have time and double check the clock. Besides throwing components at it, I am running out of ideas

    Please someone let me know if my thought process is entirely wrong

    Update 2:Again, not on the whole AD-DA process but it looks like things start to breakdown at IC8. I ordered one and we'll see what happens. With IC8 removed there is no noise (but no effect obviously).

    Anyone have any thoughts on the wave forms?​
    Attached Files

  • #2
    Do you have a schematic you can post?

    Comment


    • #3
      Here's the lit for the DD-3A for all to peruse. If yours is another version, let me know.
      I'll look into it in a while. Glen
      Attached Files

      Comment


      • #4
        Here is DD-3 3rd addn. Can actually read this one.
        Attached Files

        Comment


        • #5
          Another...
          Attached Files

          Comment


          • #6
            There's a link to the schematic that matches what I have in my first post
            Attached Files

            Comment


            • #7
              Originally posted by UnluckyFett View Post
              should be 5v and 12.5us rising edge to rising edge. I only had the cheap chineasieum scope today, the clock signal is present but it was only reading .5v P-P.
              Seems odd to be off by exactly a factor of 10. Any chance there is an x10 scope probe in use?

              Originally posted by Enzo
              I have a sign in my shop that says, "Never think up reasons not to check something."


              Comment


              • #8
                Yeah I was using a cheap multimeter scope. The tektronix read 5v.

                Comment


                • #9
                  I found the problem. It was a bad DRAM. Swapped in a new IC and it's working perfectly

                  Comment

                  Working...
                  X