Test power lines with diode mode

[corrize]

Hello, I have a noob question about troubleshooting (for laptop in my case but, it's could be general).

I saw someone on video testing power lines witn diode mode. He saw 0.1v on 5v line and said « it's too low », and compared with 3.3v line and find 0.3v (seems OK for him). How did he know it's too low or not pls ?

[redwire]

Re: Test power lines with diode mode

Semiconductors have a (IC substrate diode) threshold voltage of about 0.3V-0.7V and using a multimeter on diode-test it will first charge up capacitors and then settle on a voltage reading for that line.
Anything less than 0.3V is considered a short.

[corrize]

Re: Test power lines with diode mode

Thanks, it's clear.