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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 the controller board is connected, even the 3V3 rail on the CB is 1.8-1.9Vtesting
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