Currently restoring one of these with the same problem. Your demonstration on how to balance the meter has been a great help. Many Thanks! just subscribed.
Well, I could send you the one from my meter once one of my viewers sends me a replacement for mine. I'm assuming you are referring to the plate behind the needle.
Why? You have the zero adjustment, is that not enough? As far as I know, those meters (the needle ones) have one working position - horizontal or vertical. Yours is to be used vertical, if I am correct. The pivot point screws, from what I have seen are brass or have small stones (jewels) like clock mechanisms and never plastic. I had hand multimeters that never required a procedure like yours to adjust, a simple zero adjusting was enough. Also, panel meters (vertical mount, with many many hours) that never required opening to adjust. Maybe your meter is a very very low quality?
Ok, you are correct that the meter will always be used in the vertical position. Unfortunately the meter was sticking indicating a problem with the movement. At almost 70 years old, plastics can shrink or deform slightly and cause the movement to be pinched slightly so by loosening the screw about 1/16 can overcome that and allow the meter to move freely. The 2nd problem was the mechanical zero, adjusting it all the way to the left it would still not zero mechanically hence the need to balance the movement. After that I tried to calibrate the meter without success that's why I tested the micro amp full scale reading. It should take 200uA to drive the meter full scale but instead takes almost 300uA for a full scale reading. All of that said, this meter was part of an estate that was given to me . It was in a garage for many years probably because it wasn't working. It appears there is an electrical problem with the movement itself.
Horizontally used meters that are out of balance just get nervous when they are off balance. Vertical meters lose linearity because there is a non-constant gravity pull depending on the pointer angle if the balance is off.
I agree to a point, accuracy for this meter new should be 5% of full scale and unless I change some of the 1% resistors that are 4% to 7% out of tolerance. The issue that I asked about is the meter movement should be 200ua full scale and why is full scale now 300ua and can that be corrected. The meter can't repeat a reading on any scale and I believe the movement itself is damaged and needs to be replaced.
Currently restoring one of these with the same problem. Your demonstration on how to balance the meter has been a great help. Many Thanks! just subscribed.
Happy to hear you subscribed and the video helped. Good luck with yours, I'm stuck on mine, my latest video is asking for help from the community.
@@ko2fjb Thanks Fred. I've bought another one for spares off ebay as it was cheap enough, not working but visually in better condition than mine.
Very Interesting Fred, I never knew of the 3 balance arms... Great stuff!
Thanks Fred !
Loss of sensitivity is likely due to loss of magnetism in the movements magnet (due to age).
I have 2 of these with the face-plates completely smashed! Know where I might buy them?
Well, I could send you the one from my meter once one of my viewers sends me a replacement for mine. I'm assuming you are referring to the plate behind the needle.
@@ko2fjb - No, it's the plastic face plate. I fell and destroyed BOTH!
@tubeDude48 ok, when i get the replacement, if its not broken i'll let you know.
@@ko2fjb - Thank You!
Vtvm tube meter more than 70 yes
Why? You have the zero adjustment, is that not enough? As far as I know, those meters (the needle ones) have one working position - horizontal or vertical. Yours is to be used vertical, if I am correct. The pivot point screws, from what I have seen are brass or have small stones (jewels) like clock mechanisms and never plastic. I had hand multimeters that never required a procedure like yours to adjust, a simple zero adjusting was enough. Also, panel meters (vertical mount, with many many hours) that never required opening to adjust.
Maybe your meter is a very very low quality?
Ok, you are correct that the meter will always be used in the vertical position. Unfortunately the meter was sticking indicating a problem with the movement. At almost 70 years old, plastics can shrink or deform slightly and cause the movement to be pinched slightly so by loosening the screw about 1/16 can overcome that and allow the meter to move freely. The 2nd problem was the mechanical zero, adjusting it all the way to the left it would still not zero mechanically hence the need to balance the movement.
After that I tried to calibrate the meter without success that's why I tested the micro amp full scale reading. It should take 200uA to drive the meter full scale but instead takes almost 300uA for a full scale reading.
All of that said, this meter was part of an estate that was given to me . It was in a garage for many years probably because it wasn't working.
It appears there is an electrical problem with the movement itself.
@@ko2fjb You are right, I later saw your other video about his meter. It is the age.
Horizontally used meters that are out of balance just get nervous when they are off balance. Vertical meters lose linearity because there is a non-constant gravity pull depending on the pointer angle if the balance is off.
It is an analog meter that was never accurate new .Adust with mechanical screw and move on.
I agree to a point, accuracy for this meter new should be 5% of full scale and unless I change some of the 1% resistors that are 4% to 7% out of tolerance.
The issue that I asked about is the meter movement should be 200ua full scale and why is full scale now 300ua and can that be corrected.
The meter can't repeat a reading on any scale and I believe the movement itself is damaged and needs to be replaced.
25 min to say something that takes 15 seconds. FFS