Gents Pulsynetic Master Clock - advice required

Discussion in 'Electric Horology' started by puffernutter, Jan 30, 2017.

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  1. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    Hello all,

    I am new to this and have done some surfing and I expect the answer I'm looking for is around here somewhere - it's just finding it!

    I am a new owner of a Gents Pulsynetic Master Clock. I've never dealt with one before although I am an electrical engineer and build steam engines for a hobby, so I should have the technical bases covered.

    I purchased this as a working clock, unfortunately it never has and after playing with it, getting nowhere and leaving it for a year, I've come back to it again.

    I've found a copy of the Installation Instructions and I believe I have set up the contacts etc. (push off, back stop and contact pieces), according to the gap given. Initially the clock would only run for about 4 minutes, however after careful oiling (with clock oil) of all the pivots, it now continues to run.

    BUT (there's always a BUT!)

    I am using a 12v sealed (gel) lead acid battery (fully charged) and have also checked the current, when at 0.22A that is not enough to lift the gravity lever to the latched position, so I am running with zero resistance.

    However (another BUT) even on zero resistance this is not enough energy to always re-latch gravity lever, neither does it always pulse the slave clock.

    So, my question is, what do I need to tinker with to get the "hefty thunk" that I have read is associated with this clock!

    Cheers

    Peter
     
  2. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    There is a chance that the one or both coils are shorted inside.
    Also, check the starting position of the armature. If too far from
    the pole pieces it won't have enough pull to bring the armature
    close enough.
    Remember the inverse square law. It is very unforgiving.
    Tinker Dwight
     
  3. rogerj

    rogerj Registered User

    Dec 21, 2014
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    #3 rogerj, Jan 31, 2017
    Last edited: Jan 31, 2017
    Hi Peter..It is indeed a rare thing to hear of a Gents clock failing to go ! I expect you know these are generally thought of as the agricultural tractor of the master clock world. If you have followed the set-up instructions then electrical seems likely. Mine is stored away at the moment so can't immediately go to it and measure the coils. There are two coils and it's unlikely they have both gone faulty so I suggest using a digital multi meter to measure the resistance of each coil..If they are not the same there is a problem.
    However, there is another issue....the failure to advance the slave clock even with no series resistance in circuit.
    These Gent slaves are simple and reliable so you need to determine if the slave clock itself is faulty. They are about 5 ohms and can easily be tested by tapping avross a 1.2 volt rechargeable battery. (or a 1.5 volt of course ) Roger
    edit..I assume the "slave" is the built in pilot dial.. If not disconnect the remote dial as a first step.
    This thread: https://mb.nawcc.org/showthread.php?32897-Correct-Voltage-for-Gents-Pulsynetic-Master-Clock says coil resistance is 4 ohms. Other related threads show below..
     
  4. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    There is the possibility that someone miswired the coils. Two apposing fields
    could cancel.
    Tinker Dwight
     
  5. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    All, thank you for all the support and advice, my apologies for the tardy reply, I'm away a lot, so I have a lot of time to think and little time to action.

    However, I've had a play again tonight. One issue I noticed is that the roller wasn't running freely, this was cause by interference from the plate that holds the end of the gravity arm. So I moved that to give a small amount of clearance, adjusted the yoke to give me a smaller gap to the armature (inverse square law) did the rest of the set up again and we're worse. What happens is that over a period of time the energy imparted is not really enough and when we get to the deeper notch it doesn't always get to the next tooth and it double, treble or even quadruple tries before it latches again. It advanced the clock 4 hours in the space of 2!

    I have now checked that roller, ensured the outer was oil free (as was where it contacted), so if I get a chance next, I'll look at the electrical side and check resistances (although gut feel is that it is probably OK).

    One think I am learning is that whilst these are supposed to be "bomb proof" that is only after they are set up correctly and that set up is very sensitive to very small
    changes!

    One final thing, I messed with the slave (there was an adjustment in the top RH corner as you look at the back of it and at least that works now. All it needs is the right number of pulses the right time apart!

    Cheers


    Peter
     
  6. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    All,

    Thank you for you previous advice.

    Another quick question please! I have the clock running reliably and the slave. I now wish to add more slaves. I have two wires coming to the slave dial, how do I add slaves, series or parallel and what thickness wire. I should say that I've tried both, with 1mm FT&E and nothing from the additional slave :-(

    Cheers

    Peter
     
  7. rogerj

    rogerj Registered User

    Dec 21, 2014
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    Hi..Ideally use Gents slaves clocks.The movement are easily recognised ( http://www.hvtesla.com/masters/slaves_intro.html ) and you should have one in your C7 master clock. I realise that as an electrician you have a plentiful supply of T&E but light bell wire is all you really need.
    These instructions may be useful : http://www.masterclock.2ge.hu/Instru...ransmitter.PDF

    First, check your slave dials for correct operation. Quickly dabbing across the terminals with a 1.5 volt battery should make it step the half minutes. Adjust the mechanism if necessary. The circuit is a simple series loop. Break into the existing circuit and connect the other dial(s) in series. Include your Fluke test meter in the circuit, short the clock's reset contacts and adjust the resistance in the clock case for a loop current of 0.22 amps. Presto !
     
  8. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    Not that simple (unfortunately).

    The mechanism looks identical to what is in the clock, however a 1.5v battery (AA) cell creates a very light "tick" noise with no discernible movement on the solenoid (I have cleaned and carefully oiled the mechanism).

    From the terminals at the top of the slave I measure a resistance of 32ohms. So, with a 1.5v battery that will only give 47mA, I should be looking for 220mA, so I'm light somewhere! To get 220mA I'll need around 7v.

    Cheers

    Peter
     
  9. rogerj

    rogerj Registered User

    Dec 21, 2014
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    Hi Peter . Can you confirm that the movement in the clock and the one you are testing are both identical to the the one in the first link in reply #7.
    Assuming it is, the coil in your slave is faulty. Just to be sure I just tested a Gents clock with a 1.5 cell and it works fine. Two of mine measure 9 and 7 ohms.
     
  10. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    #10 puffernutter, Mar 8, 2017
    Last edited: Mar 8, 2017
    [​IMG][​IMG]

    These are the two movements to the top the one with the master, to the bottom is the one in separate clock that is measuring in excess of 32ohms across the coil. Both Gents I think, in fact the slave have Puls-synetic on the dial.
     

    Attached Files:

  11. rogerj

    rogerj Registered User

    Dec 21, 2014
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    Yes , definitely both Gents slave clocks..You will note that the pilot dial movement is marked 4 ohms (4R) ..I can't find a definitive statement on the net about the resistance of Gents slaves but elsewhere on this forum a contributor stated that he believes that "all Gents coils are 4 ohms". (doesn't explain why mine measure 9 ohms but at least it works). Perhaps someone with expert Gents knowledge will contribute and offer info on a mechanism with a 32 ohms coil. Maybe there is an explanation but I can still only suggest that it's faulty..
     
  12. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    Thank you for the clarification. I'll check again, possibly uncover the sleeving on the coil and try there.

    Cheers

    Peter
     
  13. John UK

    John UK Registered User

    Mar 25, 2006
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    One does occasionally encounter Gents (and Synchronome) clocks with higher impedances. GPO versions of Synchronome slaves sometimes had higher impedances (usually I think about 7.5 Ohms rather than about 4 Ohms), and some Gents masters were designed for 24V, or 48V systems. There doesn't seem to be any consistency in marking these unusual impedance coils.
     
  14. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    One step forward - two back! A schoolboy error! I measured the impedance of the leads - they contributed 26+ ohms, so my coil is probably about right. I now have it working from a 1.5v battery, but still wont work from the master mechanism.

    I had it sited locally and it would "twitch", I adjusted the spring tension and it started moving on the pulse. I then put it in the room near its final (but with the full length of cable) and it worked. I then positioned it on the wall in it's final location and started the master off with them both reading 10.00 (convenient at the time). It did nothing, when I looked again at around midnight, the slave was reading 10.25 and it hasn't moved since!

    I'm going to take it off the wall again. Bring it nearer the master on a shorter cable and get it working reliably (if it will) before I go to the final position again!

    Almost, but not quite there!

    Cheers

    Peter
     
  15. Tinker Dwight

    Tinker Dwight Registered User

    Oct 11, 2010
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    Did you measure the loop current?
    Tinker Dwight
     
  16. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    Not sure I understand the question, sorry.

    10.00 and 10.25 are times, not current!

    Cheers

    Peter
     
  17. Tinker Dwight

    Tinker Dwight Registered User

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    The clocks are intended to be run from a current loop.
    It is the current that actuates the magnetic field.
    The voltage it related to the resistance of the wire and the coil.
    The current of the loop should be measured and adjusted.
    I believe it was stated that the loop current should be 225 ma.
    You may need an adjustable power resistor to set it correctly.
    If you have the right current the wire can be most any gauge and
    any reasonable length ( even a 1/4 mile is reasonable for the switching
    rate you are using ).
    Try setting it up with that.
    Tinker Dwight
     
  18. rogerj

    rogerj Registered User

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    #18 rogerj, Mar 9, 2017
    Last edited: Mar 9, 2017
    I came back with some information but it seems you have made a big leap forward. As Tinker says..loop current. The resistance in the wiring should not matter as long as the battery voltage is high enough to achieve the loop current..
    Before seeing this latest development I had looked out all the Gents stuff I have. Two complete slaves ( A &B ) and three movements.(C, D & E ) ) Careful measuring between the soldered connections rather than between the slightly corroded screw terminal gave :
    A: 4 ohms, B: 6 ohms (on this one the coil is marked 6 )
    C: 3.3 ohms, D: 4 ohms, E: 8.5 ohms
    A & B still have the Bakelite cover which are both marked: working current 0.22A - Max: 0.27 A, Min .17 A
    Ohms laws dictates that a 4 ohm coil should tick with only .88 volts across it.
    The 8.5 ohm coil does advance with 1.5 volts but at the lower limit of current specified..It is a little sluggish and it needs to be well fettled.
    So, all Gents slaves are not necessarily 4 ohms. But at least I don't need to go to speculate about one with 32 ohm coil ;-)
    Roger
    whoops... hadn't noticed Tinkers reply #17
    If Peters clock is complete there is a power resistor in the case for setting the loop current..
     
  19. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    Another schoolboy error!

    Before dinner (we have dinner not "tea" in the West Country :D )

    I was looking at the full set of instructions from Gents and was intrigued by the part about slave clocks and accumulators etc., particularly the comment about going up to 80v! Then it occurred to me that as the slave (local slave) in the "transmitter" was working (eventually!) I hadn't actually measured the current, then I also noted that the resistor was set at the minimum and any increase in resistance and it would stop the local slave working, so I was probably at the minimum current (from a 12v lead acid battery) so driving a more remote slave as well was probably a slave too far! So, armed with a second 12v battery (to give 24v) an ammeter and setting the resistance to maximum) I adjusted the current to 0.22A. Guess what? OK, only 40 minutes so far, but the remote slave is ticking every 30 seconds nicely. :clap:

    I'll report back tomorrow (after Crufts) and let you know if it is still ticking away nicely and whether it's missed any pulses!

    Cheers

    Peter
     
  20. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    Still ticking nicely! Spot on!

    Cheers

    Peter
     
  21. puffernutter

    puffernutter Registered User

    Aug 13, 2015
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    Not missed a beat (pulse!) yet.

    I now have two more slaves to add - wish me luck!

    Cheers

    Peter
     
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