Bulova Accutron 219 coil testing, schematics

[ManSkirtBrew]

I've got a 219 that I'm playing with. When I hook it up to the 700 test set, it pegs the ammeter, so I'm trying to determine if I need a new coil.

I first determined that the previous owner had screwed the battery strap to the main plate, causing a dead short. After I fixed that, it still doesn't run, regardless of how much tapping I do on the side. The ammeter needle stays all the way to the right.

My understanding is the 219 uses most of the same bits from the 218, with the obvious omission of one coil.

 

And this is what my 219 looks like:

Testing resistance across the two brass prongs of the coil only gives me 900 ohms, where I'd expect 5-10k.

But because there's only one coil here, I can't be sure I'm testing the right bits. Is the feedback coil included here? Where are the contacts for it? Are there any diagrams for the 219 out there?

I do see that Cas-ker has coils and circuit boards available for $50 each, but I'd love to know if this is bad first. Plus I love learning this stuff.

So assuming they just removed the cell coil and left the rest of the circuit the same, this is how I matched my 219 to the schematic:

I was measuring between E and G, so across F1. 900 ohms makes a little more sense. I'll try tomorrow between F and E. To tired and too much Scotch to do more tonight

Edited June 15, 2023 by ManSkirtBrew
Uploaded better 218 schematic

[JohnR725]

6 hours ago, ManSkirtBrew said:

But because there's only one coil here, I can't be sure I'm testing the right bits. Is the feedback coil included here? Where are the contacts for it? Are there any diagrams for the 219 out there?

For unknown reasons the 219 service manual is incredibly hard to find. But I was sure that I had a PDF in the computer doing a search revealed A two-part PDF and the quality sucked.

So I was thinking what would be the chance that I could figure out where my physical copy is and find it without searching the entire section. Fortunately I guessed correctly. That's now been scanned and attached as a PDF and much more readable condition than the previous thing I downloaded. I think it will answer the questions you have testing the various components etc.

 

Accutron 219 ServiceManual.PDF

[nickelsilver]

Don't want to hijack, but if anyone has a service manual for the 2242 I'd love a copy.

[JohnR725]

54 minutes ago, nickelsilver said:

but if anyone has a service manual for the 2242 I'd love a copy.

Always best to do a search in the computer before looking for something physical to scan.

Then I see the number two at the very end of your number which technically the manual does not have?

Accutron 224 ServiceManual.pdf

[nickelsilver]

Thanks John! Looks the same.

[ManSkirtBrew]

3 hours ago, JohnR725 said:

That's now been scanned and attached as a PDF

You are an absolute hero! I had found an addendum to this, but it didn't include the coil testing part.

Looks like my hunch on the schematic was correct; I was measuring the phase/feedback coil.

Also interesting is how simplified the phasing procedure is from the 214 and 218 manuals. It's basically just "turn the eccentric until it runs and call it a day."

[JohnR725]

4 hours ago, ManSkirtBrew said:

how simplified the phasing procedure is from the 214 and 218 manuals

Yes they figured out things easier with time for instance the ESA 9162 Phasing is interesting. They give you a little test plug you put it in and you just the fingers to be in the proper place for the plug you remove the plug you put the watch together and if you're lucky it might just run otherwise you barely tweak the phasing screw. Plus the electronic part is separate from mechanical part

Oh thinking about phasing I've attached a couple of things. The article on basically where the factory way back when was servicing the watch to run at a much higher voltage so silver cells for the most part shouldn't be a problem. Even the specifications sheet shows that the high-voltage phasing voltages much higher than it says in the service manual itself.

1996-08-web horological times Accutron silver cells phasing.pdf Accutron_Specifications.pdf

[ManSkirtBrew]

Okay, according to my DMM, the drive coil is reading 12k ohms, and the feedback coil about 900 ohms. Which seems high and low, respectively, based on what we'd expect for the 218 movements.

But at least we know the coils aren't open, and maybe they wound the coils differently for the 219, so:

I rotated the index and pawl fingers away from the index wheel just to make sure the only thing I was testing was whether the fork would start vibrating. Hooked up 1.35 volts through my 700 test set, set it to READ MICROAMPS, and it pegs the meter no matter how much tapping I do on the side of the movement.

I really hate to just blindly replace the circuit board and have it not be the problem. Any other test suggestions?

My first instinct is to test the almost 50 year old capacitor, but I don't have a DMM with capacitance testing. I did test resistance across it and it shows infinite, but I know it's possible that the cap charged up so quickly my meter didn't pick it up, since it is a tiny little guy at 220nF.

I'm tempted to just replace the cap and see if it fixes it.

 

Edited June 20, 2023 by ManSkirtBrew

[ManSkirtBrew]

Update! Treated myself to a new DMM that tests capacitance, as well as a resistance range large enough for the 2.2M ohm resistor.

The capacitor reads 0.05nF, the resistor 3.2M ohm. I've got replacements on their way from Digikey.

[ManSkirtBrew]

It worked!

I measured the new cap and resistor to make sure my meter wasn't the problem, and they were 220nF and 2.2M ohms, as expected. I did have to open up the holes for the capacitor's leads slightly with the smallest drill bit I had (0.026", #71), and I didn't snip the leads short enough, but otherwise it went together with no issues.

Popped in a battery and it's humming away! I tried to take a video but my phone camera won't pick up the hum or the vibration, so I popped it on my timegrapher's microphone. Watch-o-Scope has a nice mode where you can just view what the microphone hears:

I have the software set to the shortest sweep time it can do, which is 1/8 second. So if the fork is vibrating at 360Hz, we should expect to see 360/8 ticks: 45.

And what do you know, I count 45!

The only concern I have now is when hooked up to the 700 test set, it still pegs the ammeter despite the fork visibly and audibly vibrating. That does seem to suggest the magnet has lost some of its strength, but I'm going to clean and lubricate it and see if I can get it running well anyway.

Edited June 30, 2023 by ManSkirtBrew

[LittleWatchShop]

Nice soldering job!

[HectorLooi]

4 hours ago, ManSkirtBrew said:

The only concern I have now is when hooked up to the 700 test set, it still pegs the ammeter despite the fork visibly and audibly vibrating

If the pawl and index fingers are lifted off the index wheel, does the meter still peg out?

If the current is so high, I'm afraid the battery won't last long. Maybe only a month ir two.

[ManSkirtBrew]

5 hours ago, HectorLooi said:

If the pawl and index fingers are lifted off the index wheel, does the meter still peg out?

Yes, the index wheel isn't even installed at this point. Just the fork and the electronics.

[ManSkirtBrew]

Well that was a very short lived victory.

 

[JohnR725]

it's a shame the pivot wasn't on the other end. Then you could try to re-pivot. But it's very difficult to hold the wheel and pivot the end that you have not impossible just difficult. So now you're going to have to find a another watch movement on eBay which is interesting thing unless the seller tells you what idiots. Usually the 218 has the crown of the 4 o'clock position but they can't remember if the 219 follows exactly the same position. On the other hand will give you more tuning fork watches the play with.

Then if you reassemble with out the wheel are you getting enough fork vibration to move the index wheel?

[LittleWatchShop]

56 minutes ago, ManSkirtBrew said:

Well that was a very short lived victory.

 

Send it to me. I will attempt a repivot. No guts, no glory! Free

[ManSkirtBrew]

On 7/4/2023 at 6:35 PM, JohnR725 said:

Then if you reassemble with out the wheel are you getting enough fork vibration to move the index wheel?

Well I had to find out. Assembled without the 4th wheel. Movement is cleaned, but not lubricated (since I'll be taking it apart again to put a 4th wheel in).

And the answer is yes! YouTube video link here.

But it does require plucking the tuning fork to get it started, and it still pegs the ammeter. Neither are encouraging signs, but it sure feels great to see it run.

And lest we forget, penny for scale. This still blows my mind.

[Alastair]

In pic above--the index gauge is clearly resting on the hack pin. This will be causing your excess current.

Absolutely nothing must hinder the action of fork--or it will register higher current draw.

[ManSkirtBrew]

On 8/3/2023 at 6:01 PM, Alastair said:

In pic above--the index gauge is clearly resting on the hack pin

It was manually turned away while I was installing the train and bridge. You'll notice the index jewel isn't contacting the index wheel.

Finally got back to installing the 4th wheel again today. Got it back together and started phasing. Decided to test out my new microscope camera with a video.

I think my original feeling that the fork is partially de-magnetized is correct. It won't run unless the fork is manually plucked, even if I tap the side hard enough that I can see the fork tines vibrating.

Edit to note that also at low voltages, the index wheel stops at the same point. What I'm not sure about yet is whether it's because there is an issue with the teeth, or just because it's so out of round, as many index wheels seem to be.

It also won't start humming until about 1.2v. The other 219 I just repaired easily started at 1.05v.

Still, it's pretty great seeing it spin away.

I do have a spare movement, so I may steal that fork. For now, it's time for some Scotch and a break.

Edited August 24, 2023 by ManSkirtBrew

[ManSkirtBrew]

On 8/23/2023 at 9:44 PM, ManSkirtBrew said:

I think my original feeling that the fork is partially de-magnetized is correct.

I checked the strength against the fork in the donor movement, and there was a very obvious difference. I tried picking up the "L" case back wrench as suggested by Bulova, and only the donor fork would lift the handle.

Put the donor fork in the movement, got the train together, got the fingers against the index wheel, applied power and bam, started right up at 1.35v with no tapping.

Such a fascinating movement!

Got the calendar works together last night, now on to cleaning up the case and sourcing a bracelet. The case is pretty beat up and may be an opportunity to learn buffing and plating, but for now I want to just get it cased up and work on my grandfather's 218.

Pictures coming soon

[ManSkirtBrew]

Cased up and running! Unfortunately, despite the crystal opening in the case measuring 32mm, I ordered a 30mm and 30.1mm crystal for reasons unknown.

The old crystal isn't a tight fit, so I still have to replace it, and find a nice bracelet. But I'd say I can feel pretty good about it running strong after all the work I put into it.

[ManSkirtBrew]

This actually brings up a question, maybe of watch ethics: this crystal is in fine shape, but just doesn't have enough tension to hold it in. I can get a NOS crystal for $22 from the 'bay, but I also have Hypno GS cement in stock. Is there a compelling reason not to use it, other than the fact that it just feels wrong to do?

I mean, I'm not building a museum piece here, I just want to wear it.

[RichardHarris123]

I see no reason not to glue it.

[rehajm]

15 minutes ago, ManSkirtBrew said:

I mean, I'm not building a museum piece here, I just want to wear it.

I'd think different if it were going up for sale but if it's your watch have at it. I'm regularly reminded of the granddaughter in the watch trade who inherited grandma's lovely vintage Cartier, then discovers grandma had taken it to the jeweler to trade out the mechanical movement for a cheap quartz...

It's your thing- do what you wanna do!

[ManSkirtBrew]

3 minutes ago, rehajm said:

It's your thing- do what you wanna do!

Thanks for the affirmation. Growing up as the son of an antique car restoring dad, "keeping it original" is always at the fore of my brain, but I guess it does need to be applied with some reason. Occasionally