That is a seriously good result and a very nice restoration of the meter!
I do have a bunch of old AVO VCM CT160, MK III and Mk IV movements that I will try something similar with when I have some time. However most of these meters will need a refurbishing of the pivot points as they have all got problems at the resting position of the needle where I have been told that the pivots have been worn down with age and use. But this gives hope to being able to fix the magnet problem.
Thanks for showing how you solved this and congratulations to a job well done!
/Martin
Quote:
Originally Posted by Electronpusher0
SO, I gave in and made my Neodymium magnet replacement with iron pole pieces.
I used a 30mm X 30mm X 20mm magnet I bought on ebay and used mild steel for the pole pieces, not ideal I know, but its all I had.
I had to space out the 20mm to the required gap of 31.7mm using some iron from another scrap meter.
I attach photos of the assembly.
And the result? The meter now has a sensitivity of 320uA!!! It is very heavily damped and now requires a bit of tapping to get it to finally settle however.
I have shunted the meter with a 47ohm resistor and now have a meter that is 584uA fsd.
I will now calibrate the AVO tester and see how it performs.
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