{Chrysler 300} 300F clock info

[John Grady <jkg@xxxxxxxxxxxxxxxxx>]

After converting 3-4 F clocks to japanese quartz movements — ( not easy , remote D battery , lots of improv to use old hands etc , the setting knob ends up behind clock , no EL lighting on hands— see Timesavers web site) —I decided to look this time more at the nice looking stock clock .  I had never seen one working right even after a clock guy “fixed “ one for me long ago for 150$ etc .  lasted a month . 
I was prompted   by opening one in perfect shape from a low mileage car , but not working at all . 
Thinking is , once balance wheel and second hand is running rest of it is geared down highly reduced speed high torque should all work .And all brass , should not rust etc 
So —I found out a problem ,present  in all of them .
When contact to wind the spring drive closes every few minutes , it literally “ throws “ a wheel and spring rather violently back to stretch the spring and run clock ; I had noticed in the past that the long arm (not the spring side of this set up ) mounted on the drive coil hinge was often flailing around inside but it worked again — if re positioned right  . Careful inspection : there is a little brass flap (square thing in  picture 1) supposed to limit back recoil of that long piece , —-the stop flap soon bends at food crease (!) after thousands of hits and then the arm swings way out ( instead of 1/4” it should move ) so it will never wind again . Even worse it hits a brass mount post in the clock and being live turns on the coil steady which blows fuse .   aha !!  I bent brass flap back to stop it , clock works! But within an hour it bent again . Fatigued thin brass ! a design error. Flap is too weak . 
So I added a 1/4” x 2/56 screw as a backup stop by drilling a tiny hole in phenolic back and tapping . (picture 2) Clock running 3 days perfect time . Went on line about ? oil balance wheel or not . Some dissension  but 80/20 yes with lightest mobil 1 or watch oil . A tiny drop on tip of a wire . Does not impact time , but can impact first start up from off . Saw that . 
Second : surprising — very high current pulse but extremely short —- 4 amps , maybe 1/100 second — comparable to ignition point current . Average draw is very low , thousandths  of amp . 

Arm has no contact protection , standard fare now in relay EE ....  as no small diodes were around at design time in 50’s so I added an arc suppression diode ( 1 N4007 ) across the coil , will extend contact life 25x ! There will be no more arc , picture 3 . Polarity critical , bar or cathode end of diode goes to inlet + 12 v — solder there , other end to solder tab on the drive coil end .    

I really wish I had looked carefully long ago , instead of “ they are always junk clocks “ “ never work” 
I was wrong ..  adjusted nothing , accurate within 30 seconds after 3 days . 

One more thing working well !
John G 



Sent from my iPhone not by choice 

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