Debugging my DINX1/CORE combination

Testing/Troubleshooting
1

I finally managed to put my MidiCV-interface components into a case,  but unfortunately the buttons don’t work anymore now. They have been fully functional before  >:(

So far, I haven’t figured out the reason. I guess, something is wrong with the communication of the DINX1 and the CORE module.

I have taken the modules out of the case again and made some measurements. This is what I have found out:

  • Pressing the buttons on the DINX1 pulls the inputs from 5V to 0V.

  • There is a clock signal at the DINX1.

  • The LD-Line of the DINX1’s shift register is constantly 5V, no matter if a button is pressed.

  • The serial output of the DINX1 is a rectangular signal, which loses amplitude when one of the 4 buttons is pressed.

Can anybody tell my, if that sounds correct so far? Seems like I’m lacking some basic knowledge here…

2

How did you measure the RC (=LD) line, with a multimeter, or with a scope? Because the RC signal is a very short pulse, which toggles each mS

Here the link to the troubleshooting guide:

http://www.midibox.org/dokuwiki/din_module?s=dinx4

The srio_interconnection_test allows you to check, if the signals are still available at the 74HC165, or if there are shorts.

Also the midio128 check could make sense - just to ensure that there isn’t a usage issue with MBCV

Best Regards, Thorsten.

3

I found the reason in the meantime: It was a short caused by the screws with which I mounted the board to the frontplate. I looked for this in the first round, but obviously not thoroughly enough…