This is a weird one - have had 2B in service for three years, but it crashed last week. Rebuilt with a new Pi 2B+, but saw undervolt errors on the rebuilt system that would have gone unnoticed, so this is probably what caused the crash.
The system has two USB NICs, .. so first upped the USB current to 1.2A, but still getting undervolt log messages (but NO lightening bolt on the screen).
Tested three new Pis, same symptoms.
Put a DMM on P2, rock solid 5.01VDC.
Measured the load current, 600mA.
Replaced the USB NICs, same symptoms.
Tried a powered USB HUB, no connectivity.
Tried two different external PS units, but they were actually worse - undervolt AND alerts.
So, .. would really appreciate input from the community!
1) What could be causing the undervolt when P2 is stable at +5? There may be a power issue with the two USB NICs, but with 1.2A available and a total load about 600Ma, .. ??
2) Why would the Pi not like an external PS? During one test it even thew errors with a 60W Anker. What is the Pi complaining about?