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More Faulty BM786

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EEVblog:
Two faulty BM786's with what looks like the same fault. Intermittent power on problem, and it's NOT the switch.
And they are 1yr apart in manufacture.

EDITED VERSION:



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floobydust:
I have seen crystal oscillators not start up reliably with issues on the IC (transconductance) or crystal or tuning caps being off. Try touch a pin to poke that circuit. It can explain the wonky power consumption if the gate is floating in linear mode. Or is it an RC oscillator now, the old 786 has no crystal populated (by the DMM IC) in your video and I forgot if you took it off.
Handling the meter does warm it up which might be why leaving it alone (cools off) makes a difference.

gabiz_ro:
There seems to be a little delay when switch off until current drop to 0,so some part of soft on-off seems to work,at least for off part.

Most probably is something on power switch taht provide not enough power to mcu or even mcu hang on boot sequence

Maybe power switched by rotary isn't all that is required to power on.
I don't own this model so I can't test.
With no batteries switch rotary to some position and insert battery,is it powering on?
If in sleep mode switching rotary to another position wake it from sleep?
There may be some tracks on rotary switch that send some pulse during movement to mcu that may be required to reset sleep timer counter but also maybe required at power up.

Can't remember from older video but I think programmer cable powered multimeter even it was in off position,so simple check just by connecting cable to PC.

EEVblog:
NOTE: I've now posted an edited shorter version of this on the 2nd channel, linked above.

EEVblog:
CORRECTION: Serial numbers are only 1 week apart. Fist two digits are year.

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