Electronics > Repair

Nanking MF47 - Cannot adjust needle to zero (Solved)


This is a old analog meter with no pcb, it belonged to my grandpa. The components are wired and mounted on a transparent orange plastic kinda board.

I noticed that the readings aren't accurate and that I cannot adjust needle to zero by turning the panel center pin screw, doesn't reach zero mark. Disassembling the panel shows the end of the center pin screw is a little scratched from wear.

How can I solve the adjustment problem ?  Can I adjust manually, without the center pin?
What about increasing the thickness of the pin ?

As far as I remember you set the needle position rotating the U shaped piece of metal below the center. The other side of the spring that is connected to the needle is connected to this. However, yours might be different of course.

Check the adjuster forks are astride the hair spring still, I have seen many cases where the meter has been knocked or dropped and this caused the hair spring to come out of the fork.

Solved by rotating the U shaped piece of metal to the left.

Putting back the panel together was hard, the center adjustment screw pin barely fit inside the U.


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