Do you really mean the older "Pi B+", or the newer "Pi 3B+" ?
I can only assume you have a very uncalibrated meter as the voltages are all way above what they would be expected to be. Even if you were putting in well over 5V one wouldn't expect the regulated 3V3 to stray much from 3V3.LawnMowerMan wrote: ↑Fri Jul 06, 2018 6:02 pmVoltage check on 5V pin:
Pi-FAILS + supply-A 6.64V
Pi-FAILS + supply-B 6.82.V
Voltage check on 5V pin:
PI-WORKS + supply-B 6.80V while booted, 6.94V after power-off
Voltage check on 3.3V pin:
PI-WORKS + supply-B 4.45V while booted, 4.47V after power-off
PI-WORKS + supply-A 4.52Vwhile booted, 5.54V after power-off
The usual cause for abnormal readings is a low battery in the meter.
The range that the PSU will tolerate on its input is not connected to the output voltage, because any supply suitable for a Pi will be regulated.
Use of the test points is a matter of convenience. It will not affect the result.
Batteries are a very poor reference, since the voltage varies considerably with the state of charge.
Not relevant in this case, since 5V is present on the board and 3V3 is not. (A short from 3V3 to 0V on the SDCard slot or elsewhere is just about conceivable, but should not affect a new Pi on first use.)
+1. From the information the OP gives, this sounds like a rare "dead on arrival" Pi. If, of course, the OP is sure that nothing could have damaged the Pi when it was first connected and powered on.
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