Finally have the confidence to work on my grandfather's 1973 Accutron 218

[ManSkirtBrew]

My grandfather died back in 2004, and my mom gave me his Accutron. I've wanted to restore it for years, and finally have the experience and confidence to do so.

Of course the first thing I did was slip and bend the pawl finger, but at least it's not my first rodeo and I was able to fix that.

Not running with an Accu-Cell, but the index wheel is pretty grungy so I took it apart and powered the circuit without the train installed. The fork kicks up, but instead of a hum I get a pulsing vibration. Never seen that before.

I checked the electronics, and the resistor reads about 990 ohms instead of the 2,200 ohms we expect. The capacitor reads 197 pF, which is reasonably close to the 220 pF we're looking for.

I'm going to give it a thorough cleaning and see if it'll run, but I have a feeling I'm going to be replacing the resistor and capacitor. A much harder task on the 218 than on the 219.

 

 

Edit to add in some circuit diagrams, in case anyone is here for 218 diagnosis help:

Edited January 2 by ManSkirtBrew
Add schematics

[Waggy]

Good luck, let us know how i is going!

[HectorLooi]

7 hours ago, ManSkirtBrew said:

not my first rodeo and I was able to fix that.

I might not know anything about rodeos, but.....

7 hours ago, ManSkirtBrew said:

checked the electronics, and the resistor reads about 990 ohms instead of the 2,200 ohms we expect. The capacitor reads 197 pF, which is reasonably close to the 220 pF we're looking for.

Your values for the resistor and capacitor are out by thousands!

[JohnR725]

always interesting when you have sources of different reference material. So for instance it doesn't look like they're looking at the phase sensing coil that are only looking at the drive coils. Plus slight variations from the resistance values that you have.

[ManSkirtBrew]

2 hours ago, HectorLooi said:

Your values for the resistor and capacitor are out by thousands!

hah you're right, I always forget if it's 220 pico or nano Farads, and meant to look it up before posting.

Guess it's soldering time.

[ManSkirtBrew]

This is my opportunity to upgrade from my 20 year old Weller soldering iron and get some super fine tips. Time to tackle some other projects while we wait on the FedEx truck.

[rehajm]

14 minutes ago, ManSkirtBrew said:

This is my opportunity to upgrade from my 20 year old Weller soldering iron and get some super fine tips. Time to tackle some other projects while we wait on the FedEx truck.

...that's a sexy bit of kit!

[ManSkirtBrew]

On 1/2/2024 at 1:54 PM, rehajm said:

...that's a sexy bit of kit!

It's pretty wonderful. Heats up extremely quickly, and tip changes are a breeze. I'm using an 0.5mm round point tip.

Here's the patient before I started:

I managed to get the cap unsoldered, but the connection from the transistor to the resistor refuses to come apart. I decided to just snip it and stop putting heat into the transistor, which I'm reusing.

Here I laid out the new components.

Snipped the leads and bent them into shape.

I tried to mimic the old layout, but since there's room in here I may rearrange things to give me more working room around that lug up top. I'm open to suggestions, here!

All right, I'm pretty proud of this. Now to see if I can get that ground strap soldered in.

Well, maybe not the prettiest, but hopefully functional. Time to clean it up and test.

OH MY GOD IT WORKED! A little tap on the side and the fork started right up at 1.35 volts. Huzzah for tiny soldering!

And one more picture in situ. Standard calibrated penny for scale.

[TimeWerks]

Nice neat soldering job, looks very good! Congratulations and thanks for sharing.  Your success motivates me to look at  a few Accutrons that need some attention. 

[ManSkirtBrew]

Well that was a short lived victory. Somehow while bringing in a sharp oiler to oil the cap jewels in the mainplate, I managed to jab it directly into one of the coils and destroy it.

I still have no idea how I did it, but I am beside myself. I'm so upset. Like yeah, I can replace the coil, but just the fact that I am incapable of not jamming a sharpened steel pick into my grandfather's watch makes me want to throw all of my tools in the trash and take up knitting.

Well, I powered through my shame and measured the coil, and it looks like the enamel did its job and I might not have destroyed it after all. Fingers crossed.

[TimeWerks]

Hopefully it is ok.  One way to protect from damage is to temporarily cover the coils with a small clean leather buff stick before you approach the watch with something sharp near the coils.  Like removing or installing screws. Ounce of prevention is worth it.  ( Of course I still have to remember to do that myself.   )

[ManSkirtBrew]

18 hours ago, TimeWerks said:

Like removing or installing screws.

I have a new rule when working on Accutrons: no turning screws without a pair of tweezers guiding the blade of the screwdriver. Because I also have a bad habit of bending pawl fingers...

But that said, this could not be a more beautiful sight:

I followed Rob Berkavicius's procedures here and it runs smoothly from 1.05 to 1.90v, which is more than enough range for a silver oxide cell.

Now to clean up the case and assemble the calendar works!

[LittleWatchShop]

On 1/13/2024 at 11:09 AM, ManSkirtBrew said:

have a new rule when working on Accutrons: no turning screws without a pair of tweezers guiding the blade of the screwdriver. Because I also have a bad habit of bending pawl fingers

Yes, I use this procedure from time to time myself.  It is fool proof.

Another thing I do when in the danger zone...I set the driver, turn the screw a full rotation (whatever my fingers deem a full rotation), then I LIFT THE DRIVER, reverse the rotation while free of the screw, then replace the driver and repeat a full rotation.  What this method does is it avoids the event where you are pressing down on the top of the screw driver with one finger while removing your twisting fingers.  This moment leaves the screw driver with only two points of attachment (your finger and the screw).  The screw is slippery and often the driver slips off into a coil or a balance wheel, or something else.

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How did you fix the coil??

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I have that same soldering station.  Been Hakko fan for years.

[ManSkirtBrew]

12 minutes ago, LittleWatchShop said:

How did you fix the coil??

I checked the resistance of the coil and it turns out I didn't cut the wire, somehow.

I applied a tiny dot of epoxy over the scratch to seal it from the elements.

[ManSkirtBrew]

After a long delay, I finally got a larger o-ring to seal the crystal. Somehow it's not thick enough to really grab the crystal, despite being the same size as the old one.

Either way, the design of the case very firmly seals the crystal against the inside of the case, so I'm just going to wear it and keep it out of the sink.

I think Pop-pop would be proud.

And just to round out the whole story, mom texted me this after I sent pictures:

Quote

Hey Joe
The watch looks brand new - great job!
I bought that watch in 1973 for Nanny to give to Pop for his birthday.  My boss at the time took me to his jeweler on Wall Street. He gave me a discount and it cost me around $200 which was expensive then.