Why did it quit? Why?

Discussion in 'Electric Horology' started by bangster, Sep 17, 2009.

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  1. bangster

    bangster Moderator
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    Jan 1, 2005
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    This is the same clock from the "Won't self start" thread. After I worked over the gearbox a couple of times, it seemed cured. Self-started every time. Ran without interruptions —AT THE RIGHT SPEED— for over 12 hours.

    It was done, right? Put everything back together, and in the case, and wham! allofasudden, for no apparent reason, it quit.
    ingraham mvt 1.jpg
    And this time, it REALLY quit. No amount of boosting the rotor with a finger will make it go. It's as if the stator doesn't recognize that there's even a rotor there. Well...not exactly. If I give the rotor a backward boost, it snaps back forward a few degrees. So there's some level of interaction there.

    Here's where my ignorance-level about things electrical comes into play. What the hell could have happened to make it instantly go dead? There's continuity through the coil. There's juice getting to the coil.

    I need help from those of you what have some understanding of these things.

    bangster
     
  2. davefr

    davefr Registered User
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    Nov 29, 2008
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    I can't tell from the image what kind of rotor this thing has but my guess is the bushings and gears within the rotor are worn to the point where you have gear clash. Gear clash in rotors can be very intermittent. I've seen Telechron rotors that will run for hours and then lock up hard. Others will lock up right away.

    The only way to be 100% sure is to remove the gear train from the rotor and inspect it.
     
  3. bangster

    bangster Moderator
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    Oh, I've already done that. Had it open, inspected, everything hunky-dory there, just yesterday. One brass gear, two fiber, and the pinion on the rotor shaft, examined under high magnification. Nothing wrong with any of them. Lubed and re-assembled. That's when it finally started behaving like it is supposed to.

    Until it quit without warning.

    Plus, it doesn't "feel" like a mechanical problem. The rotor isn't seized in any way. It just doesn't do anything when it's plugged in.

    That's why I'm baffled.

    bangster
     
  4. Kevin W.

    Kevin W. Registered User
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    Apr 11, 2002
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    Bang i am not a electrician but have a few thoughts on this.Could there be a short? Is the circuit open? Scottie likely knows much more about these than i.
     
  5. bkerr

    bkerr Registered User
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    Nov 29, 2007
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    Bang, is it in a metal case?:confused:
     
  6. eskmill

    eskmill Registered User
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    Aug 24, 2000
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    Bangster.
    Your photo shows a metal face in front of the movement. It looks like steel/iron. How is the face fastened to the movement?

    Reason for query: Any ferro-magnetic material bridging the magnetic gap of the motor stator poles acts as a magnetic shunt.
     
  7. bangster

    bangster Moderator
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    IT WAS A MECHANICAL PROBLEM AFTER ALL!!

    Not in the rotor gearbox, but a misaligned wheel in the train. I finally went back to basics, did a complete disassembly (again), and worked up from there until I found the culprit, and fixed his wagon. Causing just enough bind at certain points to stop the drive. Even though it didn't feel like a bind when I turned the rotor, that's what it was. It's now running properly, and I yam once again a happy camper.

    Thanks to y'all for your suggestions and help.

    Les: That steel front plate is the backing plate for the dial. It's attached with nuts and lock washers to the front pillars (with rubber cushioning washers in between the steel plate and the clock plate). Apparently, it's far enough away from the motor not to affect anything.

    Incidentally, that mode of attachment was a pain in the kiester. First, you have to assemble the movement without the backing plate. Then you have to remove the front pillar nuts again, in order to put on the rubber washers and backing plate. Because there are springs in there for a couple of levers, you gotta disconnect the springs before removing the nuts; otherwise the movement explodes and you start over. Then you gotta worry the springs back on.

    I resolved that by wrapping a couple of strong rubber bands around the movement, to hold the clock plate in place while I removed the nuts. Then I installed the backing plate, and cut the rubber bands. :thumb:

    Whoever came up with that design deserves punishment.

    bangster.
     
  8. bkerr

    bkerr Registered User
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    Always seems to be the simple stuff.

    Bang, you little sneak! You had us all looking at the electrical side. It sure is fun when you get'em figured out though.
     
  9. Mike Phelan

    Mike Phelan Registered User

    Dec 17, 2003
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    If it was O/C, there would be no magnetism and therefore no buzz if you bring something steel near it.
    A few shorted turns will stop the clock, make it get very hot, but will not show up with a normal meter. That said, everyone should have a £5 digital meter or three - not just for electric clocks, either.
    Proves how little power is available on these motors - it doesn't take much to stop them.
    Good result, Bang!
     

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