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About tabularasa

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    MIDIbox Newbie
  1. BLM 16x16+X PCB and case order [CLOSED/waitlist]

      I'm in with one of each.
  2. SEQ4 Heidenreich Case Bulk 2014 / 2015

    Great, I received the shipping info. Thanks a lot for organizing this group buy.
  3. SEQ V4 Wilba panel LED troubleshooting

    That's a good addition and can save others from troubleshooting. Thanks Tim
  4. SEQ V4 Wilba panel LED troubleshooting

    I really tried hard but could not find bad solder joints ;-) The good thing is that I learned a lot about shift registers and how the panel works. I only killed two fully operable 74HC595s ;-)
  5. SEQ V4 Wilba panel LED troubleshooting

    I feel so embarrassed. I checked the LED orientation at least 5 times and I always overlooked that the Step View LED has a different orientation than its neighbours in that row. Thanks a lot for the help, now everything works :thumbsup:
  6. SEQ V4 Wilba panel LED troubleshooting

    Thanks a lot for the hints.   Today I resoldered the 2 74HC595 today but there is no difference. The orientation of the resistor networks is correct andI think they are in line to read encoders and buttons which is working fine.   There is a resistance of 43 kOhm between the QA-QH outputs and the ground connector of the 595 shiftregister, is this normal or shall I look look for shorts?   I can also measure a resistance between the outputs of the shifregister 1 and 2 (Out vs DOUT) but these are serveral MOhm, so I don't think this is the root cause of the problem. . Is there a good methology to track down the root cause?
  7. Hello,   I soldered the LEDs on a SEQ V4 panel and some of them keep glowing dim when they should be off and one is always glowing very bright. I checked for shorts but couldn't find anything. Then I changed the 74HC595s but I have still the same effect. Debugging is really difficult since I can always measure a voltage between the pins of the LEDs.   The config file is is a copy from here:   According to Wilba's schematic all of the missbehaving LEDs share a connection to Out14 but I could no find a shortcut between this line and other connections on the board.   The Track and Track Group LEDs are less bright if I switch on the step LEDs.   The power source I'm using is a Meanwell RTP-60B with 100kHz switching frequency connected to J2 and on Core STM32. Might there probably an issue with the multiplexing frequency or do you have an idea what could be the root cause? I'm quiet lost and don't know how I can effectively troubleshoot this issue.     Martin