borfo Posted March 15, 2014 Report Share Posted March 15, 2014 I just finished building a V4l with the standard frontpanel, and things seem to be working fine, but several of the LEDs aren't working. I'm tracing the paths and trying to figure this out myself, but the pattern of non-working LEDs makes me think that someone who's more familiar with the V4L and the Core LPC17 module might spot the issue right away and save me some troubleshooting time. All LEDs work except the following: LED 17, 18, 19, 22, 27, 29, 30, 31, 32 (step indicator leds, second horizontal row from top) LED 6, 22, 38, 54 (sixth column of LEDs from the left side) LED 11, 27, 43, 59 (sixth column of LEDs from the right side) I attached a picture of the top panel schematic with the nonworking LEDs circled in red. Buttons all seem to work. Diode and LED orientation is correct. There is continuity between the non-working LEDs and their connecting points on P6 and P7 headers. Not sure about connectivity to the transistors yet... Still trying to figure out the traces there. Anyway, if anyone has any hints about where I should be looking, that would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
borfo Posted March 15, 2014 Author Report Share Posted March 15, 2014 (edited) Hm... I just unplugged everything and plugged it back in... The vertical columns of non-working leds moved, so I'm guessing the vertical columns are a problem with one of the 10 pin cables. Second horizontal row LEDs don't work no matter which way I orient the 16 pin cable though. edit: Two of the 10 pin cables had problems... I'll fix those, and I bet the vertical columns of LEDs will work. But the 16 pin cable (P3 to J15A) is fine - from the schematic, it looks like the horizontal row issue wouldn't be related to the 10 pin cables. Possible that I've got a bad transistor maybe? Edited March 15, 2014 by borfo Quote Link to comment Share on other sites More sharing options...
TK. Posted March 16, 2014 Report Share Posted March 16, 2014 The vertical row is driven by two lines which go to J15A via two transistors - a broken transistor is unlikely, check the 16 pin cable again. Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
borfo Posted March 23, 2014 Author Report Share Posted March 23, 2014 (edited) Thanks - I just redid all my cables. They're all tested and they're fine. Fixing those did fix the vertical rows, but the horizontal row of current step indicator LEDs is still not working - the first three LEDs and the last four LEDs in the row don't light. (LEDs 17-19 and 29-32) All the other LEDs work fine now. Any idea what I should be looking at to fix LEDs 17-19 and 29-32? Not that it's really all that big a deal not having them working... I can live without a few of the step indicators. This is a great little sequencer, by the way. Lots of fun. Looking forward to getting my V4 parts and building that... Edited March 23, 2014 by borfo Quote Link to comment Share on other sites More sharing options...
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