MSXV PD Validation

Owned by Jenna Kong
Last updated: Aug 01, 2023
2 min read

04-07-2023

  • VBAT and 3V3 rails in working condition, 5V outputs 0.2V

13-07-2023

  • tested a few times, working fine however the voltage lines incorrect

  • split moment, drawing too much current at an extremely low voltage, and smoke

  • gound and power are shorted

  • next steps: find the shorted component (the one that is smoking), use a thermal camera

15-07-2023

Need to order adapter for thermal camera

20-07-2023

  • tested impedance between components separating ground and power, seems to be none of components so far

  • thermal camera working, used to determine the zener diode between power and ground may be the problem

“Desolder the diode and see if the short goes away. Test the diode when its off the board (for both forward and reverse conduction).Forward conduction (as a diode normally should conduct), them diode should have a voltage drop about 0.6V. You can test this with the diode test mode on a multimeter. Reverse conduction can be tested with a power supply. Set a low current limit and start at a low voltage with the diode connected in reverse. Then start slowly increasing the voltage and see when the diode starts to conduct - make sure it matches the datasheet. Should be around 16V.Get a new diode as well and do the same tests and ensure that the values you get for that one are similar.“

23-07-2023

  • zener diode taken off, and the short stopped after removing

  • testing the diode for bias, seems like the diode was the problem

25-07-2023

  • controller board is not the problem, correctly outputs 3V3 (when testing independently)

  • when the controller board is connected and the PD is supplied with a 12V, the 3V3 voltage rail is supplied ~1.8-1.9V (with test points both on the pd and cb)

  • it was suspected it may be the CB connector, however, the 3V3 on the CB is also affected when testing

01-08-2023

  • The pins of the connector do not look properly connected, so resoldered a new connector to the PD board

  • Tested all the pins for shorts, seem to be all properly connected

  • Checked ground and power for shorts, high resistivity > not shorted

  • With a PSU, 12V was supplied to the board with the CB connected

  • Proper 12V at input wires, and the 3V3 correctly outputs ~3.3V at multiple points on the board

  • 5V buck converted outputs ~5.5V

Input power supply: 12V, 0.042A