Connect with us

Strange analog meter movement problem

Discussion in 'Electronic Repair' started by Sam Goldwasser, Feb 20, 2004.

Scroll to continue with content
  1. Now here's one you don't see everyday.

    I have a taut band (I believe) D'Arsonval meter movement with a
    plastic faceplate that seems to have areas of permanently static charge.
    So, the needle gets stuck or gets pulled or pushed toward or away from
    certain positions. I've removed the faceplate and it then works normally.
    Moving the faceplate near the needle results in the needle changing
    position. I've tried the usual approaches to getting rid of static but
    it always comes back.

    Assuming anyone has seen this before, is there any solution other than
    replacing the faceplate? Is there such a thing as "degaussing" for
    electrostatic charges? Destatic-ing? :)

    I'd rather not have to fabricate a replacement.

    Thanks.

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
    TimBandTech likes this.
  2. Your post makes me want to say "rub a small amount of liquid dish
    detergent on the inside of the meter face".

    The problem is, I can't remember if that's a solution for the problem,
    or I am remembering a solution to some other problem.

    Michael
     
    TimBandTech likes this.
  3. Dbowey

    Dbowey Guest

    Michael posted:
    << Your post makes me want to say "rub a small amount of liquid dish
    detergent on the inside of the meter face".

    The problem is, I can't remember if that's a solution for the problem,
    or I am remembering a solution to some other problem. >>

    That is the correct answer. I've used it many times.

    Don
     
  4. Daniel Rudy

    Daniel Rudy Guest

    And somewhere around the time of 02/19/2004 19:42, the world stopped and
    listened as Dbowey contributed the following to humanity:
    Why not use an anti-static spray on it? They don't cost much, and
    because the residue is slightly conductive (depending on which one you
    use), the metal case of the meter (If it has a metal case) would serve
    as an electrical ground. But, then again, I don't know if the spray
    would harm the plastic either.
     
  5. Russ Verdon

    Russ Verdon Guest

    There was a post on an electronics group the other day about this same
    problem. A guy on a boat was having trouble with an in strument meter.
    An amateur radio respondee advised that he sprayed the plastic with fabric
    conditioner IIRC as required.

    Russell
     
  6. Thanks. Yes, I tried cleaning the inside but that didn't help.

    I may try the applying a HV AC field across aluminum foil plates
    to see if I can depolarize the plastic on the assumption that it
    somehow acquired some internal polarization from an "event". :)

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     

  7. Just a shot in the dark here, but I seem to remember insuring the
    conductivity across a clear material by taking a cotton ball and using
    it to rub dry graphite into the material. Works great for making
    replacement films for electrostatic speakers too. You may also want to
    make a conductive path from the lens to the system ground as well.
    Foil tape should work for this.
     
  8. Not sure if I read that right:? Pulled and pushed as the needle
    moves? That would seem to imply reversing charges (polarity
    changes) as the needle moves under the faceplate

    snip
     
  9. You do have to be able to see through this so a visible coatin of
    graphite powder or aluminum strips isn't exactly a viable solution. :)

    I finally fixed it by rubbing with a clothes dryer anti-cling sheet but
    had to do both inside and outside.

    Thanks for all the replies.

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
  10. Yes. Up around 2/3 scale it might tend to get stuck while it would tend
    to want to avoid around 0.

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
  11. Ken G.

    Ken G. Guest

    Get a digital meter .
     
  12. No. There are times when an analog meter is far superior as when
    following a trend. Anyhow, this is for an existing instrument
    where that isn't an option.

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
  13. Jim Adney

    Jim Adney Guest

    I'm just guessing here, so be gentle with me. How about rubbing it
    VERY lightly with a (possibly warm) anti-static dryer sheet?

    -
     
  14. Yes, that finally was the solution. Maybe more determined cleaning with
    dishwashing liquid would also have suceeded. The dryer sheets worked
    the first time though I did have to do both inside and outside.

    Thanks.

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
  15. Thanks. What do you think about this? That area corresponds to
    the needle's most active area. It may have, over time, swept
    that area relatively free from outgassing by the scale paint
    graduations? Or there are very dense etc., markings at the ends.

    Oh well, it's raining today....
    ..
     
  16. Too much in depth analysis can be a bad thing sometimes. :)
    Probably the correct explanation!

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
  17. Then I 'll have to start drinking again!
    Timely that too, thanks again Sam.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-