Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks



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#393759 08/17/17 12:03 PM
Joined: Dec 2006
Posts: 128
Shade Tree Mechanic
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Shade Tree Mechanic
Joined: Dec 2006
Posts: 128
I wonder if anyone has repair experience with these clocks. I have destroyed several trying to learn how. Is the condenser to store energy to raise the magnetic field on discharge or only for spark suppression at the points on the balance wheel?

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Joined: Oct 2004
Posts: 535
Oil Can Mechanic
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Oil Can Mechanic
Joined: Oct 2004
Posts: 535
I have been working on a potential G&D article about these clocks as I have two. I think the condensor is just there for spark suppression so the points will last longer. I think the long term solution is to either:
1)use a 555 IC chip to power the coil (hands motor) and forget about using the balance wheel and points.
2) use a transistor or IC to power the coil so the balance wheel and points would use a tiny amount of current as a timing signal.

Joined: Dec 2006
Posts: 128
Shade Tree Mechanic
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Shade Tree Mechanic
Joined: Dec 2006
Posts: 128
Thanks for your reply. The balance wheel itself is much like a synchronous electric clock with the pole pieces magnetized by the pulse from the coil when it is energized. Difficult to locate the rest position of the balance wheel since the contact to its shaft cannot make a connection or the setting knob will not work. Also why does the shaft contact alternate from top to bottom. I like the idea of a timer chip but such a modification would be beyond me.

Joined: Oct 2004
Posts: 535
Oil Can Mechanic
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Oil Can Mechanic
Joined: Oct 2004
Posts: 535
Here is my explanation of how the balance wheel and setting knob shaft interact.
When the clock has been disconnected from power for a while, the balance wheel comes to rest in its “home” position. This position is marked by a scored line on the balance wheel. Normally the balance wheel switch is closed in this position, so when power is connected to the clock, the balance wheel will rotate counter-clockwise and the balance wheel will oscillate as long as power is connected. If the switch were not closed, the balance wheel would not oscillate. Delco thoughtfully provided a way to manually apply power to the coil. Pulling out the hands setting knob closes a switch which activates the coil to start oscillation.

Last edited by chevy50jim; 09/03/17 07:39 PM.
Joined: Dec 2006
Posts: 128
Shade Tree Mechanic
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Shade Tree Mechanic
Joined: Dec 2006
Posts: 128
The problem is what happens when the magnetic pulse that moves the balance wheel is too weak to maintain the oscillation. I do not believe the balance wheel should rest in contact with spring. I negates the reason for the set knob switch. I wonder if resistance in the balance wheel ground circuit through the contact spring, shaft and pivots and hair spring may reduce the strength of the coils magnetic field. the 555 still sounds good.

Joined: Dec 2009
Posts: 1,072
ChatMaster - 1,000
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ChatMaster - 1,000
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Posts: 1,072
i had an electric clock in my 50 coupe i gave up on it from old notes that i have somewhere they were really only good for a year two at the most so i too 3 clocks to my watch maker friend he made me 2 good ones and i have been very happy just winding the clock up it is good for 12 hours i think who drives that long any how i just wind it up careful not to over wind and go from there


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