Smart Panel Meter - can it be modified to read down to zero volts? [SOLVED]

[ccktek]

Solution for a similar different meter with same problem.

https://www.eevblog.com/forum/projects/digital-power-meter-mod-for-voltages-down-to-zero/msg4909307/#msg4909307

[VK5POI]

I have two of these meters. They are V5.0, PZEM-051 pcb's
I want to be able to read 5 V dc, but alas they only go down to 6.5V!!

I will be using a PC PSU for 12v dc and 5v dc. Obviously the 12v readout is ok
12v for a few scanners etc, and 5v for a raspberry pi and usb charge circuits.
I'd really like to make sure I have correct voltage ( even though PC PSU's are incredibly robust)

I have tried all the suggestions, but no luck with an outcome.
Has anyone been able to get the display to read 5v,

[Zero999]

Perhaps they've changed the design.

Please post some pictures of the PCB. They need to be clear enough to read the part numbers and ideally see the tracks on the board.

[Seekonk]

That is a tough one.  Both sense and power are tied after D1. Sense is R7. They have obviously compensated for voltage drop in the reading.  To leave it in or not is the question.  R5 the 10 ohm can be removed and power applied there into Q1. Might want to add a diode for protection. Didn't feel like cutting into mine.  Let us know how accurate it is with or without diode and if it goes down to zero.

[Seekonk]

Solved???

Curiosity got the best of me and I cut the sense trace to R7 on a brand new meter.  It will not even start up, screen blanked, till the sense voltage gets over 6V.  Just what was done to solve this?