This is awesome. I have the exact same movement in my 1976 Corvette. After checking it out I suspected a bad solenoid, but after you said they're so old now I realized it's got to be the problem. Thanks for this!
Just so that everyone knows ... The reason that the solenoid windings overheat and burn out, is not intuitive. They are designed to draw current "momentarily" as the contacts close, then the winding action opens the contacts again. Although the solenoid coil draws a fair amount of current, it does so only briefly, after which, the clock runs for a couple of minutes. This allows time for the solenoid coil to cool sufficiently between power pulses. The problem ( over-heating ) occurs when the vehicle's battery is low, as is common if the vehicle is not used for several months, or if the lights are accidentally left on and battery voltage is reduced. In this scenerio, the contacts of the clock remain closed; energizing the solenoid coil ... but, since the battery is low, there is not enough voltage applied to develop the magnetic force needed to retract the winding mechanism. Thus, the winding process "stalls" for lack of voltage. However, the coil remains energized with enough voltage to cause it to overheat, since it was not designed to dissipate heat from "continuous duty" operation. Usually, the enamel coating of the coil windings breaks down with the heat generated, causing electrical shorts against adjacent windings, leading to increased current draw, increased heat, and the eventual demise of the solenoid coil. To repair the coil, remove the damaged windings, and rewind with new enamel coated wire of the same diameter and length. A hand-held drill motor (variable speed) is helpful for rewinding the coil spool, and makes for a very neat result. Once you have repaired the clock and verified its operation, do yourself a favor, and install a 1 ampere slow-blow fuse in-line on the positive power wire. This will protect the clock from future low voltage damage ... unless you enjoyed the repair process and look forward to doing again sometime.
Good video, but I already knew all this. I don't know how to rewind a tiny solenoid though. That's what I was hoping you where going to demonstrate. You know where I can learn that part of the repair? Or is there a vendor that sells the right size replacement solenoid? Thanks
I re-wound this solenoid with 26ga. hookup wire. It would be better to use magnet wire but I didn't have any on hand. There's certainly a wire gauge and number of winds that are supposed to be used but I was unable to find that documented anywhere. So, Just wrapped it with enough turns until it filled the core. Provided you can get the mechanical action desired without burning the windings it's good to go.
I have a similar clock in my car. The coil/solenoid shows 0 ohms so I believe it is shorted. The coil is about 1/2" long. Can you tell me how you got the coil out of the metal box in which it resides? I'm struggling to figure out how to do that without destroying it.
On mine the metal frame the coil was installed in was riveted together. I used a drill to carefully drill off the rivet heads. It then came apart easily. On reassembly I just used some epoxy to hold it all back together. Has worked fine so far.
I've rewound one using 26g magnet wire, but it doesn't seem to respond similarly. I'm wondering if it's the amps I'm using. I have one hooked up to a 12v 0.5A AC>DC transformer and it hums but won't connect and throw the mechanism. There's not enough "strength" to do so. Do I need more amps?
0.5A is not enough. The solenoid will pull about 1.5A. It doesn't draw that for more than a few milliseconds, but it will need that amount of power available.
Just connect a capacitor in parallel across the solenoid leads. The stored electrical energy in the capacitor will assist your power supply to provide enough DC to operate the solenoid.
This is awesome. I have the exact same movement in my 1976 Corvette. After checking it out I suspected a bad solenoid, but after you said they're so old now I realized it's got to be the problem. Thanks for this!
TY - nice to listen to someone who can explain something in a straightforward manner.
Just so that everyone knows ...
The reason that the solenoid windings overheat and burn out, is not intuitive.
They are designed to draw current "momentarily" as the contacts close, then the winding action opens the contacts again. Although the solenoid coil draws a fair amount of current, it does so only briefly, after which, the clock runs for a couple of minutes. This allows time for the solenoid coil to cool sufficiently between power pulses.
The problem ( over-heating ) occurs when the vehicle's battery is low, as is common if the vehicle is not used for several months, or if the lights are accidentally left on and battery voltage is reduced. In this scenerio, the contacts of the clock remain closed; energizing the solenoid coil ... but, since the battery is low, there is not enough voltage applied to develop the magnetic force needed to retract the winding mechanism. Thus, the winding process "stalls" for lack of voltage. However, the coil remains energized with enough voltage to cause it to overheat, since it was not designed to dissipate heat from "continuous duty" operation. Usually, the enamel coating of the coil windings breaks down with the heat generated, causing electrical shorts against adjacent windings, leading to increased current draw, increased heat, and the eventual demise of the solenoid coil.
To repair the coil, remove the damaged windings, and rewind with new enamel coated wire of the same diameter and length. A hand-held drill motor (variable speed) is helpful for rewinding the coil spool, and makes for a very neat result.
Once you have repaired the clock and verified its operation, do yourself a favor, and install a 1 ampere slow-blow fuse in-line on the positive power wire. This will protect the clock from future low voltage damage ... unless you enjoyed the repair process and look forward to doing again sometime.
Thanks for the info!
Great info!
Awesome video Thank you for posting!!!
Our clock clicks and works but it is slow. Looses about 2 or 3min per hour. Any suggestions?
Our 1957 buick has a similar clock. We test this clock and the arm on the solenoid has broken.
Good video, but I already knew all this. I don't know how to rewind a tiny solenoid though. That's what I was hoping you where going to demonstrate. You know where I can learn that part of the repair?
Or is there a vendor that sells the right size replacement solenoid?
Thanks
I re-wound this solenoid with 26ga. hookup wire. It would be better to use magnet wire but I didn't have any on hand. There's certainly a wire gauge and number of winds that are supposed to be used but I was unable to find that documented anywhere. So, Just wrapped it with enough turns until it filled the core. Provided you can get the mechanical action desired without burning the windings it's good to go.
I have a similar clock in my car. The coil/solenoid shows 0 ohms so I believe it is shorted. The coil is about 1/2" long. Can you tell me how you got the coil out of the metal box in which it resides? I'm struggling to figure out how to do that without destroying it.
On mine the metal frame the coil was installed in was riveted together. I used a drill to carefully drill off the rivet heads. It then came apart easily. On reassembly I just used some epoxy to hold it all back together. Has worked fine so far.
in my case spring is not able to move the pendulum and needs little bit of pressure then it starts moving. Do you think wd-40 would help?
hey! same here did it work?
I've rewound one using 26g magnet wire, but it doesn't seem to respond similarly. I'm wondering if it's the amps I'm using. I have one hooked up to a 12v 0.5A AC>DC transformer and it hums but won't connect and throw the mechanism. There's not enough "strength" to do so. Do I need more amps?
0.5A is not enough. The solenoid will pull about 1.5A. It doesn't draw that for more than a few milliseconds, but it will need that amount of power available.
Just connect a capacitor in parallel across the solenoid leads. The stored electrical energy in the capacitor will assist your power supply to provide enough DC to operate the solenoid.