I was trying to understand the connections in a power supply board.

It was found that anode of below diode is connected to GND and -ve terminal of bulk capacitor. Cathode of diode is connected to +ve terminal of bulk capacitor.


simulate this circuit – Schematic created using CircuitLab

One strange measurement result was found when I measured the resistance wrt GND for the 2 cases shown above. The diode orientation is not reflecting correctly while measuring the resistance wrt GND.

Has it got anything with the way the multimeter measures resistance ( by injecting a voltage thereby charging the bulk caps?)

I could find some voltage of 0.2V across diode after the above resistance measurement.

  • \$\begingroup\$ What results did you get? \$\endgroup\$ Apr 5, 2022 at 16:07

1 Answer 1


Many analog multimeters actually present a positive voltage out of the black/negative lead and vise versa.

Most digital multimeters operate the obvious way with a positive voltage from the red lead.

That would explain the results you get.

Do you have the manual of the meter? What meter is it?


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