Does anyone know if the face of these meters can be removed?

Discussion in 'General Electronics Chat' started by spinnaker, Dec 4, 2015.

  1. spinnaker

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    Oct 29, 2009
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    I have an idea for a project but if I do this I am going to want to change the scale on a meter.

    These have a nice retro look.

    http://www.ebay.com/itm/Black-AC-0-...184645?hash=item2c9e2b1545:g:L8UAAOSwyQtVpaBp


    http://www.ebay.com/itm/Round-Analo...hash=item4602321138:m:mHf9l9I1ueERlsh78fuvWiQ

    Does anyone know if the faces on these meters can be removed so I can get in and replace the scale?

    I figure I might need to contact the seller. But thought I would ask here first.

    I have used those more modern meters with the the square face before and I know they pop off but have never used these older looking meters.
     
  2. KL7AJ

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    Nov 4, 2008
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    Yes. There are probably three tiny screws near the back. REmove those and the entire mechanism will slide out of the cylindrical "shell." Be very careful not to bend the needle in the process of removing it. The same goes for replacing the meter face. That stuff is DELICATE

    Good luck!
    Eric
     
  3. spinnaker

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    Thanks! I am going to confirm with the seller but the information on the screws is going to be useful to help them to determine if it is removable.

    Yep I know how delicate they can be. Have not had one apart in eons but I do remember.
     
  4. Hypatia's Protege

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    FWIW here is an example of a similar indicator -- There are generally three fasteners at 120° intervals about the circumference - Removal of the contact-post burs is (generally) neither necessary nor recommended...

    Good luck!:)

    Best regards
    HP
    Darsonval1.JPG

    Darsonval2.JPG
     
    Last edited: Dec 4, 2015
  5. Alec_t

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    The meter in the first link seems to have cross-slotted screws in the wall of the cylindrical part. All the old-style meters I've had could be dismantled by removing screws, but a couple of recent ones have welded plastic cases.
     
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  6. spinnaker

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    Saw an article on that online. Supposedly spraying the meter cover with freeze spray pops the glue loose.
     
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  7. Aleph(0)

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    Meters like that used by ancient surplus and like hro com receivers which like KL7AJ, HP and Alec say held in case by three screws. I know cuz when teen I used to scrap old 40s military castoffs and sell parts for pin money;)
     
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  8. Aleph(0)

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    I say they're not new enough for worry about that
     
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  9. shortbus

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    Don't know about those meters but, a lot of modern plastic parts are sonic welded, rather than glued. Part of the new throw away, don't repair thinking.
     
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  10. atferrari

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    I may be deadly wrong but it looks like the needle must go out first and then the faceplate freed by loosening both screws.
     
  11. spinnaker

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    That is my fear too. I was hoping to somehow slip my own "faceplate" in behind the needle but after thinking about it, it would make trimming my faceplate to the proper size a challenge. It would also make gluing it in place problematic. I need at least 3. Wondering if I shouldn't just order one for now and see that is up.
     
  12. Hypatia's Protege

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    In my experience the bottom edge of the 'scale card' is open. --- Having removed the indicator mechanism from its case, one need only remove the two screws securing the card - then slide it up (i.e. away from the pivot) and off...

    BTW -- No worries Re: the 'zero trimmer' - it engages the indicator assembly via a 'pin and fork' arrangement and does not interfere with removal of the case.

    Best regards
    HP:)
     
  13. Hypatia's Protege

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    Once having removed it, I use the scale-card/face-plate as a template -- Alternatively you may reverse it and/or paint it then directly apply the new art...

    Best of luck!
    HP
     
  14. spinnaker

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    Looking at it more closely, it does look like it can be carefully slipped out from behind the needle. Thanks.
     
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  15. Hypatia's Protege

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    Because seeing is believing Violà!...:)
    Dar1.JPG

    Dar2.JPG
     
  16. k7elp60

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    I think the two screws just hold the scale plate.
     
  17. Hypatia's Protege

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    Correct - Their removal will not 'mess up' the instrument:)
     
  18. k7elp60

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    I used to change scales on meters quite often. I would carefully remove the existing scale. Then I would draw a new scale on the computer, print the new scale on normal printer paper and use double sided scotch transparent tape to tape the new scale to the existing scale. Then I would use an xacto hobby knife to cut the holes in the new label, then carefully reinstall the new scale.

    One possible problem if the the meter is fairly old is that the magnetism may have decreased an that my affect the accuracy of the meter.
     
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  19. spinnaker

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    Inaccurate how? Is it inconsistent across the range of deflection? Is long as the inaccuracy is consistent then that can be calibrated correct?

    Can they be degaussed? I knew I should have not thrown away my CRT degaussing coil! :(
     
  20. Hypatia's Protege

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    FWIW -- While I don't claim to be an expert in this area - I can tell you that I've never observed 'diminished' PM field magnets in D'Arsonval movements...

    Please don't try that! -- If it did anything it would further weaken the field - to say nothing of the violence it would 'visit' upon the indicator needle!:eek:

    Seriously, as long as the units have not experienced gross mishandling you should have no problems!:)

    Best regards
    HP
     
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