Seq v4+ switch troubleshooting

584b3b6a0fb185fc

Hi and happy holidays!

All my testing up to and thru the MEC switches (part 2 step 37) on the LE-MEC boards passed. I then added the assembled Mathias switches. Connected the boards via serial cables. No visible power anywhere in the device any longer (not measured but no LED’s come on). I removed one of the LE-MEC boards (the one with the beat led resistors) and it powers up but none of the switches (encoder, Mathias and lower MEC switches) on that LE-MEC send data though the encoder and MEC switches did prior to the Mathias installation. The encoders send data when rotated though but that’s it. When I swap the LE-MEC boards out, the other one produces the situation where no power seems to be present.

Should also add that the superflux LED’s do not illuminate on either board for what that’s worth.

Any suggestions on testing this condition?

LE-MEC Board that still allows powering up but not switches

LE-MEC Board that causes no power situation

Thanks!!

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For testing, does all work as expected when only the JA board is connected?
The soldering looks quite decent, so I would tend to suspect faulty IDC cables. Try to swap the cables around and see if the problem moves with the cable.
Another thing that could happen is that there is an unintentional connection between a long diode lead or encoder leg that hits a component below. Check between the boards if anything is touching.
Measure the resistance across any capacitor to check for shorts to the +5V rail.
Check all LEDs with a multimeter too: for cPixel LEDs, put the back probe on the common cathode (CC) pin and test the other dies (anodes) with the red probe; for MEC LEDs (viewed from the front), the pad with a round circle is the anode and flat line is the cathode.

584b3b6a0fb185fc

Thanks Andy.

It did and up being some unintended short. Tested caps and they all had some voltage. LED’s were good too. Removed all Matias switches, tested again and found the issue (which was actually on the reverse boards than described). trimmed end of all switches and the resistor network (which was quite possibly the cause).

Close to the end now…