NTP 920 unknown version ?

[andre tchmil]

I have a few of these NTP 920 meters here with a plastic back and a different connection layout than usual.
If I remember correct the original ones when powering up go to full scale and then slowly move back to the 0 position.

The ones I have in front of me are powered on pin 5+ and 6-. (think so !)
I slowly raised power from 5 to 24V, needle goes to full scale but doesn't drop to zero.
What am I doing wrong ?

 

[andre tchmil]

2

 

[Conviction]

I have a few of these NTP 920 meters here with a plastic back and a different connection layout than usual.
If I remember correct the original ones when powering up go to full scale and then slowly move back to the 0 position.

The ones I have in front of me are powered on pin 5+ and 6-. (think so !)
I slowly raised power from 5 to 24V, needle goes to full scale but doesn't drop to zero.
What am I doing wrong ?

The plastic backside (or is it mould?) is ANT:s work. Can you remove it?
I would try. Finding out what's going where is easy once you remove it (schematic in this thread: https://groupdiy.com/index.php?topic=59198.0). Less risky too.

I've never seen a datasheet for these M920's, so it's a guessing game, really. How did you come this far? Trial and error?

Also: if it doesn't fall back to zero, where does it fall back to? Could be as simple as adjusting P3.

 

[andre tchmil]

Hey thanks for the reply.
I will check and get back here.