Sticking reset


Brian Cracknell
 

Hello, I am having issues with my clock again. It runs fine for a while and then starts sticking as shown in this Youtube video (link below). The armature does not get grabbed by the coils properly when it should be impulsed leading to the ugly delay evident in the video which has adverse effects on timekeeping.

The current in the system is set to 330mA. Everything is clean; I have tried two separate power sources with the same result. I am currently using a mains plug-in transformer/rectifier running at 4.5 volts output with appropriate resistors. 

Previously I have fixed this issue by adjusting the backstop screw for the armature to being it closer to the coils and also adjusting the contact screw to move that the other way to keep the gap constant. That worked for a while but now the fault has reoccured. I always make sure that the screws are tightly locked in place after each adjustment so I do not think they are wobbling and reverting to a bad state.

Frustratingly, the "stickiness" may well disappear for a while the following day without any intervention and the gravity arm reverts to a healthy briskness in its reset. The improvement is generally short lived.

I would welcome any opinions.

https://youtu.be/cExBOStyNdU

Thanks 
Brian


John Hubert
 

On 29 Jul 2021, at 22:09, Brian Cracknell <brcracknell@...> wrote:

Hello, I am having issues with my clock again. It runs fine for a while and then starts sticking as shown in this Youtube video (link below). The armature does not get grabbed by the coils properly when it should be impulsed leading to the ugly delay evident in the video which has adverse effects on timekeeping.

The current in the system is set to 330mA. Everything is clean; I have tried two separate power sources with the same result. I am currently using a mains plug-in transformer/rectifier running at 4.5 volts output with appropriate resistors. 

Previously I have fixed this issue by adjusting the backstop screw for the armature to being it closer to the coils and also adjusting the contact screw to move that the other way to keep the gap constant. That worked for a while but now the fault has reoccured. I always make sure that the screws are tightly locked in place after each adjustment so I do not think they are wobbling and reverting to a bad state.

Frustratingly, the "stickiness" may well disappear for a while the following day without any intervention and the gravity arm reverts to a healthy briskness in its reset. The improvement is generally short lived.

I would welcome any opinions.

https://youtu.be/cExBOStyNdU

Thanks 
Brian


Ian Richardson
 

Hi Brian,

There is an ancient proverb which says, "if all else fails, read the instructions".

Others may contribute, but for a start I attach a pdf file of a sketch I made years ago showing the settings for the buffers, air gaps etc.  As your current seems to be correct, maybe you could try adjusting these settings.

The only other thing is to try slackening the gravity arm return spring.  Finally, make sure that the rest buffer is clean and that the armature isn't sticking to it.  Other than that, I've noting more to offer.

Good luck,
Ian R
Auvergne, France


-----Original Message-----
From: Brian Cracknell <brcracknell@...>
To: synchronome1@groups.io
Sent: Thu, 29 Jul 2021 23:09
Subject: [synchronomeelectricclock] Sticking reset

Hello, I am having issues with my clock again. It runs fine for a while and then starts sticking as shown in this Youtube video (link below). The armature does not get grabbed by the coils properly when it should be impulsed leading to the ugly delay evident in the video which has adverse effects on timekeeping.

The current in the system is set to 330mA. Everything is clean; I have tried two separate power sources with the same result. I am currently using a mains plug-in transformer/rectifier running at 4.5 volts output with appropriate resistors. 

Previously I have fixed this issue by adjusting the backstop screw for the armature to being it closer to the coils and also adjusting the contact screw to move that the other way to keep the gap constant. That worked for a while but now the fault has reoccured. I always make sure that the screws are tightly locked in place after each adjustment so I do not think they are wobbling and reverting to a bad state.

Frustratingly, the "stickiness" may well disappear for a while the following day without any intervention and the gravity arm reverts to a healthy briskness in its reset. The improvement is generally short lived.

I would welcome any opinions.

https://youtu.be/cExBOStyNdU

Thanks 
Brian


H Hal
 

My first thought is one of poor electrical contact, are the contacts in good order..polished and clean, not cleaned with any abrasive wet/dry etc but clean, no oxidation.


I would then remove the pendulum and lower the gravity arm by hand very slowly to see if it makes contact and how well it makes contact...you can measure the current whilst doing this to see if it is reduced


is your current limited by a rheostat?  these also have contacts which may be in need of cleaning



hal

uk

On 29/07/2021 22:09, Brian Cracknell wrote:
Hello, I am having issues with my clock again. It runs fine for a while and then starts sticking as shown in this Youtube video (link below). The armature does not get grabbed by the coils properly when it should be impulsed leading to the ugly delay evident in the video which has adverse effects on timekeeping.

The current in the system is set to 330mA. Everything is clean; I have tried two separate power sources with the same result. I am currently using a mains plug-in transformer/rectifier running at 4.5 volts output with appropriate resistors. 

Previously I have fixed this issue by adjusting the backstop screw for the armature to being it closer to the coils and also adjusting the contact screw to move that the other way to keep the gap constant. That worked for a while but now the fault has reoccured. I always make sure that the screws are tightly locked in place after each adjustment so I do not think they are wobbling and reverting to a bad state.

Frustratingly, the "stickiness" may well disappear for a while the following day without any intervention and the gravity arm reverts to a healthy briskness in its reset. The improvement is generally short lived.

I would welcome any opinions.

https://youtu.be/cExBOStyNdU

Thanks 
Brian


Andrew Nahum
 

I have had similar sticking on occasion. It seemed to be an electromagnetic phenomenon that developed because the ‘dwell’ of the closed contacts was too long. I have found over the years that  it’s always best to check or re-set all the gaps or clearances in the mechanism rather than use intuition to try and address a problem with particular adjustments. 


On 29 Jul 2021, at 22:23, John Hubert <jfphubert@...> wrote:

The correct adjustments are given here;



On 29 Jul 2021, at 22:09, Brian Cracknell <brcracknell@...> wrote:

Hello, I am having issues with my clock again. It runs fine for a while and then starts sticking as shown in this Youtube video (link below). The armature does not get grabbed by the coils properly when it should be impulsed leading to the ugly delay evident in the video which has adverse effects on timekeeping.

The current in the system is set to 330mA. Everything is clean; I have tried two separate power sources with the same result. I am currently using a mains plug-in transformer/rectifier running at 4.5 volts output with appropriate resistors. 

Previously I have fixed this issue by adjusting the backstop screw for the armature to being it closer to the coils and also adjusting the contact screw to move that the other way to keep the gap constant. That worked for a while but now the fault has reoccured. I always make sure that the screws are tightly locked in place after each adjustment so I do not think they are wobbling and reverting to a bad state.

Frustratingly, the "stickiness" may well disappear for a while the following day without any intervention and the gravity arm reverts to a healthy briskness in its reset. The improvement is generally short lived.

I would welcome any opinions.

https://youtu.be/cExBOStyNdU

Thanks 
Brian


Brooke Clarke
 

Hi Brian:

The sluggishness of the movement indicates that you are driving the clock with the minimum voltage needed to get the correct current based on the coil resistance.  You will get much snappier performance, i.e. more solid operation if the loop voltage is 5 to 10 times higher which requires the addition of a carbon resistor in order to maintain the correct current.  Technically you are lowering the loop time constant since T = L/R.  For example see this test where a capacitor is charged to a known voltage then applied to the coil through a resistor chosen so that the coil current is the nominal value: https://youtu.be/wwFhpL7JEk4

--
Have Fun,

Brooke Clarke
https://www.PRC68.com
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.


Brian Cracknell
 

Thank you all for your suggestions and advice over the past day. 

Based on the advice I have done the following actions:

1. Reset all the gaps to the specified settings. The clock would still not work correctly even after this. 

2. Removed and cleaned the platinum contacts. This also made no improvement. 

3. Bypassed an original, dodgy variable resistor in the cabinet which had previously been set to zero anyway and made good the connection. This did not improve things. 

4. Double-checked all connections inside the cabinet. Nothing loose was discovered. 

5. Examined an in-line fuse which I had installed a long time ago between the power source and the clock. One connection was loose. This was fixed and the clock started working correctly. 

Here is a link to the new Youtube video showing the far more satisfying clunk that now occurs. 

https://youtu.be/bOG0l323SjE
Following the expert analysis and suggestions on the Synchronome forum regarding the fault shown on the previous video, I made the following adjustments:1. R...
youtu.be

This clunk is the crispest for a long time and is mainly due to restoring the correct settings for the contact gaps, etc. From time to time I have restored these defaults but the temptation to fiddle has often proved too strong to resist and over time the settings have drifted somewhat. The main reason for this I now recall, has been to try to minimise pendulum shimmer at the moment of impulse by varying the amount of time the roller is on the pallet. Inevitably that takes you away from the precise specified settings.

So all the advice proved to be spot-on. Setting up as per instructions, searching for an electrical conductivity issue, etc.

Thanks again all!

Regards
Brian




From: synchronome1@groups.io <synchronome1@groups.io> on behalf of Brooke Clarke via groups.io <brooke@...>
Sent: 30 July 2021 16:23
To: synchronome1@groups.io <synchronome1@groups.io>
Subject: Re: [synchronomeelectricclock] Sticking reset
 
Hi Brian:

The sluggishness of the movement indicates that you are driving the clock with the minimum voltage needed to get the
correct current based on the coil resistance.  You will get much snappier performance, i.e. more solid operation if the
loop voltage is 5 to 10 times higher which requires the addition of a carbon resistor in order to maintain the correct
current.  Technically you are lowering the loop time constant since T = L/R.  For example see this test where a
capacitor is charged to a known voltage then applied to the coil through a resistor chosen so that the coil current is
the nominal value: https://youtu.be/wwFhpL7JEk4

--
Have Fun,

Brooke Clarke
https://www.PRC68.com
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.