1978 911 clock getting stuck/ ticking but not moving

[Kropka]

This subject have been talked about few times, but my issue might be slightly different.

Clock is ticking, cog with a magnet is shaking but seems not to have enough force to jerk the other cog to next position.

All internals look clean, nothing is broken, I have lubed the cogs and their mounting spots (what I could reach, so not all) with syringe and clock synthetic lube.

I replaced the capacitors since it was easy.
I checked resistance on the electromagnetic coil, I'm getting 280 ohms.

Seems that I have done all I could but the damn clock still refuse to spin. Occasionally if I give a first cog a push it will start working but it is sluggish, for instance it will move 5min in 20min.

It either needs a good clean (although it is very clean) or there is something preventing electromagnetic coil to generate full force to spin the cogs.

Any thoughts, suggestions very much appreciated.

[Kropka]

Looks like no one was able to chime in, so I went to town with my clock and was able to fix.

I have not seen anyone pointing this specific solve, but I bet what I found is a reason for most intermittently working clocks. If it ticks but either doesn't move or sometimes moves or is late, here is what I found and was able to easily fix.

Inside the clock electromagnetic coil spins a gear with attached magnet, on that gear stack there is a copper looking washer, it is important that this washer can freely spin independently of the plastic gear. Unfortunately I have not taken any pictures, so attaching one I found from a wrong angle red arrow points to the metal disc I'm referring to.

I used electronic cleaner to wash out old grease and oiled with 100% synthetic clock oil I found on amazon. Its been over 24h and clock has not missed a beat.

Very happy as I was going to give up.
Good luck

(Sorry safari doesn't want to attach this photo)

[Solamar]

Make sure photo is jpg. Png will not post


I had the exact same clock problem. 78SC, even changed the caps. It would tick, but not enough to progress to the next cog. One weird thing with mine. It would work on the desk with external power supply, but refused to run in the dash. Maybe positional?

I gave up and bought a new mechanism😁

Would like to see the picture of the washer you mention. Still have the old mechanism...

[Kropka]

Thanks for the tip on using a JPG. Still doesn't allow to add image from desktop, only a URL, I uploaded it to cloud drive, but still doesn't show up in my post, so here is the link - https://drive.google.com/file/d/1UA9bKT6Qoug7K-7xAiogMW_B2XCgf5I3/view?usp=sharing



Turns out I did take photos after I opened the clock, here is the washer I was referring to.

Just to add why it needs to spin freely... This washer seems to be in place to control the amount of spin or jerk, when my washer was stuck together, electromagnet didnt have enough force to spin fully, it kept trying (the ticking sound) but couldn't spin, now I can see that the plastic gear spins with the tick, and washer follows but much slower, muting down the rotation - I believe thats the reason for it to be there.

[dave123]

Followed Kropoka's excellent instructions, but it still didn't work, so I did the following:
1. Used electronic cleaner on copper disk, still did not work.
2. Replaced 50v capacitors with 16v and it worked.
Capacitor replacement could have been a bad solder joint or bad capacitor, but now it works and I am a happy camper.

Potentially useful data for those with this problem:
Old 16v capacitors measured 79 and 92 uf.
New 50v 100uf capacitors measured 90 and 92 uf.
New 16v 100uf capactiors measured 102 and 110uf.
Coil was 268 omhs.
Capacitors are in series, so total charge in Coulombs is Q=(C1+C2)V
So for a 12 volt input,
Q = (79+92)12= 2052 uQ for the old caps
Q50v = (90+92)12 = 2184 uQ
Q16v = (102+110)12 = 2544 uQ
If these calculations are correct, then a 20% increase will make the difference in running or not running. This may explain why some owners report the clock only working when the engine is running and providing a higher voltage. Any other ideas?