MKI / MKII S type 240 340 & Daimler 1955 - 1967

Changing the Polarity of a Smiths Pin Clock

 
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Old 02-16-2019, 03:04 PM
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Default Changing the Polarity of a Smiths Pin Clock

Hopefully answering Jagstuart's question about changing the polarity of the Smith's pin clock as fitted to the Mk2 S Type and many others.



Remove the 4 screws and link and lift off the back cover

Next remove the backplate by lifting it from the dowels

Backplate removed

Remove the insulating sleeve, screwdriver is pointing at the disc which is a diode, this has to be flipped round to face the opposite way

Undo the 2 locating pegs and carefully pull the solenoid out of the way, do not pull the wires too much especially where they join the coil

Remove the screw that holds the terminal in place and carefully lift out the rectifier housing, this can be quite brittle, so be careful

This is the diode, this needs to be taken out and flipped side for side, you can put a small dot with a marker pen on one side so you know which side is which if you drop it ! This is held in place with a spring, be careful when removing this not to break the plastic holder.

Put the diode and its housing back together in the reverse order here is the screw that holds the terminal in place

When refitting the solenoid, make sure both gaps either side of the balance wheel are even.

The clock will now be negative earth, mark the back of the clock with a sticker or some other method so that anyone following knows the polarity has been changed.

Any questions please ask.
 
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Old 02-16-2019, 04:20 PM
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send it to Mike Eck at www.jaguarclock.com.

For $85.00 he makes it work reliably and converts it to Neg. ground.
 
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Old 02-16-2019, 06:00 PM
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Thanks TJ ~ Filed away for those of us that don't want to send things halfway round the world.

Other options.

https://www.clocks4classics.com/

https://cjnwatch.co.uk/wp/smiths-car-clock/
 
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Old 02-16-2019, 08:17 PM
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thanks TJ. here's some more info for the terminally self-reliant.

https://omegaforums.net/threads/brin...to-life.29521/

more crazy small parts scattered around:

https://www.clocks4classics.com/uplo...ctions__v7.pdf


I CAN'T BELIEVE I JUST DID THAT!
 

Last edited by jagstuart; 02-16-2019 at 08:29 PM.
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Old 02-17-2019, 02:23 PM
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https://omegaforums.net/threads/brin...to-life.29521/

https://cjnwatch.co.uk/wp/smiths-car-clock/

The above link really nice chap, Chris, I had a long chat with him, he is an aircraft engineer turned watchmaker and a car enthusiast, founder member of the Area 8 JDC region. I met up with him for coffee just before Christmas, he knows his stuff and is a really helpful guy, many say that these clocks are not reliable in their original form, which to a point is true, but when cleaned adjusted and oiled properly do provide reliable service. The issue other than dirt is arcing on the pin which wears them away, this can be hugely reduced by adding a diode to stop the back emf which is what causes the arc.

I have successfully refurbished one clock with the clocks4classics circuit board, but even that had it's issues, although the pulse to the solenoid is generated by an electronic circuit, unless the jewels and other parts are cleaned and lubricated properly then the clock will still not run properly. The circuit board is not the answer to a dirty movement, but does solve an issue when the pin has burnt through. Replacing the pin is fiddly to say the least, outside my capabilities for sure, talking to Chris from cjnwatch he can replace the pins, but the cost is generally too high for most clients so they get another clock, convert to electronic or just leave it not working.
On another clock I have also got it working happily in it's original form but converted to negative earth.

Jose, Chris Eck uses a similar board to the clocks4classics circuit board, but his uses the original pin, not sure what would happen if he had one where the pin was gone, the clock I converted had no pin left (well only a stump !) , the clocks4classics circuit uses an opto sensor to pick up on the balance wheel so no mechanical contact, but this does mean that the original contacts are removed so unless you kept the parts you could not go back to original. A full clean, service and conversion would take a good watchsmith about 2 hours maybe a little more, $85 including shipping seems really cheap.

For those that don't want to send their clock off or just like to do it themselves, you have my description, for the lubrication etc. follow Chris's service PDF https://cjnwatch.co.uk/wp/wp-content...-Car-clock.pdf
 
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Old 02-17-2019, 02:54 PM
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TilleyJon, I can only speak for mine. Mike did his thing on my clock back in 2005 and it still ticks today.

I suppose you could ask him about the issue with the pin and he would know.
 
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Old 02-17-2019, 03:22 PM
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Well that was quite a bit of fun. On try #3 I sent the diode hold spring into low earth orbit and lost contact completely. MIA. The diode housing though not crispy is very thin on the back and is a POS in my opinion, (although ya gotta love British engineering). It gave up the ghost and using a piece of epoxy impregnated cardboard I made another back super-glued it to the surviving part and used 1/16 foam sheet instead of the spring to trap and tension the diode. Spring and counter balance are all working now with old positive earth terminal hooked up to the juice.


new tan cardboard square backing between the busted housing and stop tab. little square chunk of foam between contact and cardboard.
 
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Old 02-18-2019, 09:59 AM
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I think I must get myself one of these & install.



 
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Old 02-18-2019, 11:10 AM
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That's the clocks4classics one, If you do get one make sure you download the latest installation manual, some of the old info doesn't tell you to remove the insulator from the topside of the plate, and the clock won't work - ask me how I know that ! I didn't read the bit that says "download the latest manual from our website" , emailed them and they pointed out my dumb mistake very promptly .

If the jewels are dirty and the balance spring amplitude is not at least 180 deg it will keep stopping, or won't start and just keeps going through the start routine. So clean the jewels and the train and oil with some decent clock oil and it will work a dream.
 
 
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