Shoutout to the old timer who told me to check my power supply before swapping boards

He said "It's always the simple stuff first" and sure enough my Multitech PSU was outputting 11.4 volts instead of 12, which explained the random resets on that King Air Garmin 430 I was troubleshooting last Tuesday, has anyone else ever had a power supply test good on a meter but fail under load?

2 comments

2 Comments

daniel2145d ago

Shoot, 11.4 volts is barely even trying. But honestly I see people freak out about that kind of thing way too much. A lot of older avionics gear was built with enough tolerance to handle a little voltage drop anyway, especially that Garmin 430 which is pretty tough. Half the time the real problem is just a corroded ground connection or a loose pin in the connector, not the PSU being a few tenths low. That said, yeah Ive definitely seen power supplies that bench test fine with no load but then sag like crazy once you hook up something that actually draws current. It happens with cheap switching supplies all the time, they use undersized caps that can't handle the ripple. But honestly, unless you saw the unit actually rebooting when you put a real load on it, I wouldnt blame the PSU just yet. Could just be coincidence you caught a bad reading.

anderson.jason5d ago

So you're saying it's probably just a bad connector then?