RCA 98C Senior VoltOhmist Repair WIN ! Meter Movement Fixed
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- เผยแพร่เมื่อ 26 ส.ค. 2024
- Produced with CyberLink PowerDirector 14
See the written balancing procedure on my web site.
www.crankyyanke...
Go to the N1CKX page and Analog Meter Balancing
Vernon.Henry13@gmai.com
You sir, saved me, I have 2 multimeter, a Sanwa TX-301 and Simpson 269 both with same issue, now at least it is usable and very stable needle, as if the needle were trying to re-learn how to read :)
With almost zero information on repairing meter movements this was invaluable. Armed with this I have repaired my Heathkit VTVM meter that I thought I had ruined when some tiny metal pieces contaminated the movement.
Very good, useful, and educational video/tutorial! I was just right now calibrated some chinese very cheap multimeter with that technique! Best regards from Serbia and God bless You!
OhGeeze another internet expert do deal with. Ok youre famous!
Excellent. I'm working on a smaller movement in a Heathkit tube checker with a different problem, but learned a lot that's helping my project.
Very well made video and very informative. most analog meters have this ill with the owner having no idea how o fix it. what a beautiful voltage regulator dial you have
What is the device you are using to adjust the voltage of the power source? Did that come with the HP? I’ve never seen that rig before.
Very nice! I just got a WV-98C with bad meter problems myself. Very educational and entertaining!
HI Brian, seems to be a common problem with these. Good luck.
Late to the party.. but worth the wait. Very COoL electro-mechanical nirvana. I didn't know about the anti-static inside coating. Oh snap! But I think I'm good :) Wonderful meters and a good insight into meter movement mechanics (MMM). Thanks so much. Cheers
I have a similar meter I need to re-balance. There are no hair springs - just a single torsion wire.
In my case I need to reduce the weight on the opposite side of the needle.
I can't figure out how to remove what looks like varnish or glue that holds the existing coiled wire weight in position.
Can it be removed with a solvent? Could it be some sort of wax that can be melted with a miniature soldering iron?
Do I resort to trying to cut the wire using micro shears?
Hi. Another, but similar, subject. Me, and one more gentleman, are trying to understand the deviation of our Metrawatt MA 4E analogue meters, with op-amp CA3130 and voltage-to-current circuit. The meter has 10M input impedance on DC. The whole time we were thinking that the problem was/is somewhere in the electronic circuitry or the op-amp itself. We could not get the meters accurate enough over the whole scale-range. Looks like some non-linearity issue, that we can not solve solely with the gain and offset calibration and adjusting. He and me tested the meter movement alone, it is a 30uA 'classic' movement with 2 springs. i do not see any issue with the friction, so no tapping problems with this one. These are the results (mine and his almost identical, the meters are according to the serial number almost the same age): Readout meter MA4E: 30, 20, 10, 5 corresponding current: 30.26, 20.06, 9.82, 4.84uA. It has 2 V, A ranges: 30 and 100 (which is some more extended), and I am now unsure what to expect if I test 0 to 100% instead. Anyway, I was thinking maybe you would have some idea from your previous experiences about this issue. Do weights play a role when the meter is used only horizontally? I don't want to bias you to much, but 1 'wing' (right) has no weights at all, and the left one has some solder tin I believe, as the tail has considerate amount of solder attached to it. Hope you can give us some insights 🙂 Thanks in advance.
I have just tested 0 to 100% of the scale. The conclusion is that for the higher sections of the scale more current is needed (percental) then for the lower part of the scale. For example: 100% is 31.94uA and 10% is 2.8uA. Could the spring be non-linear? Tension? Homogeneity of the magnet or the helping metal construction around it? ...
@@ernestb.2377 some designs of photographic light meters have two steel arms that can be moved to increase or decrease the magnetic flux further along the needle travel. One would want to confirm mechanical balance and that the hairspring coils have no physical contact with each other first, and that there is no ferrous debris stuck to the magnet polls impeding the armature travel. (They can be removed with a steel needle.)
Excellent video and repair. Thank you.
Who gives a thumbs down on a great informational repair? Must be idiots!!!! Great video!
Hi JT. Comes with the territory.
Thanks for watching. And the nice comment.
Good job at repairing it. I'm going to calibrate mine. Luckily my movement appears to be good.
Very useful. I have an old WWII era ammeter I'm trying to refurbish. The needle seems balanced with no current through the meter. But when current is flowing (typically about 3 to 4 amps), tilting the meter causes wild changes in the reading. Remove the current, and the needle stays at zero with the same amount of tilting. I don't know how to proceed with it.
Is this an ammeter from a truck or a generator or something like that? Or is it actually a piece of test equipment
Well done. I spotted this video after commenting on the previous one.
Hi Richard, got the procedure from a 1946 Radio Amateurs Handbook. Too bad about your meter having the wings nipped off. Sounds like you will need to find another one for parts
Nice fix, and FB on the tungsten filament!
Great job. You have a great deal of patience sir.
It was the challenge. It was built by humans, must be repairable by humans. I'm a stubborn old man. Thanks for watching.
Interesting to watch. I see you tapping on the meters very often. I am working on this ISKRA MI 7043. The problem is that the right value sets after a tap 🙂 It is off by about 200mV. I can't find in the user manual that one needs to tap before taking a reading 🙂 Just kidding, what I mean, do I accept the "tapping" it should be possible to get it right even on the meters 30-40 years old. The meter is not beat up and in a very nice cosmetic state. I need to replace some resistors, that was a quick fix (5% resistors) after a blow on mA range, some 30 years ago.. Delicate (watchmakers) work on those movements, as it led me to your video. I can't really see the spring coil on your movement?
Almost all analog meters have some friction in the bearings, and "back in the day" we were taught to tap the meter to allow the needle to settle in. I have actually seen operators manuals that said to gently tap the meter to get the most accurate readings. In the "twilight " of analog meters the "Taut Band" suspensions were introduced. These eliminated the friction of the bearings.(Search Taut-Band meter). Made that video years ago and that meter was passed on long ago. There was a spring, must be hiding behind behind the "bridge" holding the bearing. I looked at the video and it isn't visible, but it was/is there. Also back in the day pilots flying planes with old "Steam Guage" analog instruments were often seen tapping the gauges for the same reason. Another problem with analog meters is that static electricity will cause problems. One trick is to wipe the face with a dryer sheet, or spritz a little alcohol on them to dissipate the static electricity. Static will cause the needle to move away from Zero and or cause erratic readings.
@theradiomechanic9625 thanks. I have several (5) analogue meters. A few have excellent movement, as I tap nothing changes. The "tapping" is a logic thing to do if you don't "trust" the initial position. Until a few days ago I naver actually opened or studied any movement. Interesting thing is too that the current needs to go through the same moving axis, with possible errors too (extra resistance). I have heard of Taut Band term but not yet looked it up what is actually is. I also see that in this ISKRA MI 7043 the magnet not so big is, and I see that within some big units (like Simpson) also a big movement inside. Anyway if friction is present then looks like no easy task to neutralize it...
The aluminum plate is glued to the plastic back plate. How did you unglue them?
Hello, I am missing one of the side weights on an old manual (hook wires to terminals for ranges) laboratory-use W. M. Welch DC voltage meter. Do you suppose that each meter model will require it’s own specific internal diameter tungsten weight? If so, I probably won’t be able to use the same bulbs/weights that you used. Any other ideas for a substitute? I’m not an electronics guy, but I have rewound numerous speed coils and a few stators for antique electric fans. Thanks, Kevin
Hi Kev, I would suspect that they vary from manufacturer to Manufacturer. However even if they are a little loose some adhesive will secure them. The weight needs to be very small yet carry some weight. The tungsten is very dense/heavy and works a treat. Just collect several types of old lamps. Headlights, tail lamps etc. Something will fit. Patience is the keyword here. Thanks for stopping by.
I need to do this to my Heathkit V-7A. Your website isn't reachable however. Do you have a new link?
What is the wheel you are moving to change the DC voltages on the power supply?
great vid - well done.
Thank you...and thanks for watching.
Hey Vern I asked it another video a while ago but I never got an answer……what is the wheel you use to dial voltages up and down? It’s really cool and I want to get one.
I’m about to undertake this surgery on a Sanwa meter movement that is out of balance. I’m all thumbs and zero for a few in meter movement battles lol. Thanks pal for another great video.
That's just a very large 10 turn wirewound potentiometer that came out of a piece of old military gear.
1000 ohms with a .05% linearity
@@theradiomechanic9625 That’s very cool. I saw it several years back in this video and loved it then. So far I’ve done the first part of your instructions. I put a replacement weight on the tailpiece and both horizontal and perpendicular are good. I’m letting the silicone cure overnight. It will definitely need a weight on the right side of the cross like yours did as when I move the zero to vertical the pointer goes negative. I suck at this but I’m taking my time and following your instructions to the letter. Thanks again.
What kind of control is that you are using to control your power supply? Kinda looks like a rotary phone dial.
HI Leland, that is a precision 10 turn Potentiometer being used as a voltage divider to allow me to get high resolution on the voltage setting. The "Dial" is a gear. Originally this pot was from some sort of positioning system and was gear driven.
If I want a 10 volt range I set my power supply to 15 or 20 volts and use the pot as a voltage divider to accurately set the voltage I want.
Can I just say.. WOW!! with my shaky hands I'm sure I would have mangled it up...
dear sir , do you have any idea if one of the "clocksprings" is missing or heavy damaged what can we do? replace it maybe what with what? thank you
Hi Konstantinos, That would be far above my poor skills to fix. These movements were produced by skilled crafts people. Where you would find a replacement spring is beyond my knowledge. The weights were fairly simple, but changing a spring would be a tough job.
The Radio Mechanic I must use an identical spring? The same as the other side? Maybe someone who fixes clocks can help me?
great youtube video extsremly informative, i have a AVO meter model 8 mk5 that needs to be balanced this video will help thank you for your work peter G0LVG
Hi Peter, had to dig into a very old handbook to find the procedure.
Great repair, I could never work with this very tiny stuff, are you sure you are not a watch maker?...LOL
I will leave mine alone, I ruined one meter by screwing with it.
Hi goat. I only had to wear 4 pairs of glasses to see the thing. I figured it didn't work anyway so I had nothing to loose.
And as an old engineer I knew used to say, " give it a try, you can't loose em' all.
Ooops I just posted on the first one and then saw this.
Now that I know what has to be done, I'm thinking my 73 year old hands may have a problem.
You where doing surgeon's work. 🩺