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Discussion Starter · #41 · (Edited)
Accutron 214 Coil types (3 wire)

Over the production years of the Accutron 214, we saw a number of variations of the coil sets. During this period, some advances were made in the miniaturization of parts and these were incorporated in the coils, somewhat simplifying them. Also, advances were made in the techniques use to wind the cell coils which had the effect of obviating the need for one capacitor. While that doesn't sound like much, it actually simplified the construction of the coils quite a bit. Compare the early 5 point coil to the latest 2 wire coil.

I have given dates on each coil type, these are approximate and based on the date codes printed on the transistor. I am open to any suggestion that might help pin them down more accurately.

The coils are listed below in chronological order:

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Discussion Starter · #42 ·
Accutron 214 coil types (2 wire)

With the later 2 wire coil types, you may notice quite a range of different transistors and capacitors used. I assume that only relates to availability of parts at the time of production, as the circuit is the same and the component values the same also. It's just the component form factors that changed.

One of the interesting things about Accutron coils is that they are all totally interchangeable throughout the production years. A 1960 movement will work fine with a 1977 coil, and vice versa.

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Discussion Starter · #44 ·
That is an interesting one. I have one the same in my M0 Accutron 203, except of course the serial number is different. Even though this movement has a date stamp of M2, it is definitely an M0 plate, as it has the hole and cutaway for the early magnetic regulator and no coil lead plate. Whatever the purpose of numbering these was, there couldn't have ever been more than 10,000 of them.

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Discussion Starter · #49 ·
A very unusual 214 coil...>

This coil showed up in a box of assorted 214 bits I got recently. I have seen literally thousands of coils in my time, but never one like this. At first it looks like a 5 point coil with an odd transistor, but it is more than that. The winding arrangement of the coils is very different from any other 214 coil I have seen. This one has the feedback coil in the component coil! The cell coil has only a drive coil, nothing more. I am sure the coil is original Bulova as the unused terminals are unsoldered and never have been (the ground plate on the cell coil), not to mention that the connections to the straps are different also. Both coil sides have ground plates. The component arrangement is similar to an early 5 point coil, except the transistor is a ceramic type used in early mil spec electronics. I have also seen transistors similar looking in balance wheel electric watches from Seiko and Citizen dating from the early 70's. One can only wonder at the motive behind this coil design, perhaps there was a threat to the usual supply of transistors at some stage and Bulova were experimenting with different options. One thing does seem clear though, Bulova didn't appear to waste much that was useable, as we have seen in the overstamped pillar plates from earlier years that were later pressed into service.

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Discussion Starter · #51 · (Edited)
Not too sure on the year it was made, but it does share features and components common to those we see in the early 5 point coils of 1960-61. I have been trying to identify the transistor used, so far with no luck. It has "J500" and "8" printed on the other side. The problem is finding early data books to look it up, most info on early transistors is found on private web pages, not much from the actual manufacturers. The crud you can see around the edges is some glue they used to stick it to the floor of the component well in the coil. I haven't cleaned it yet. I have to rewind the component coil first as the feedback winding is open. Being so unusual I think it is well worth repairing for the sake of posterity if nothing else. BTW, the size of the transistor is like a very low height TO-18 package, but without leads.

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Discussion Starter · #53 ·
Yes they would have all been assembled by hand. Having worked on and repaired many coils, it is clear that all the wires and components have had their leads pre-formed to an exact shape in jigs and cut to exactly the right length, probably to as close as 0.1mm I would say. Being pre-formed like that gives the coil sets the identical look from coil to coil and also makes it easier to do perfect solder joints. I suspect they were soldered up in an inert atmosphere, the solder in Accutron coils always looks perfect and shiny, not what you usually see with small joints soldered in air. It is also apparent they used temperature controlled soldering irons too, again because of the uniformity of the soldering. The method of wrapping wires around terminals and never relying on only solder to mechanically support a soldered joint comes from techniques used in military electronics designed for maximum reliability.

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I've been speaking to a gentleman that has quite a few accutron prototypes. This pillar plate is numbered in an interesting new spot in a similar fashion to the training movements.

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Another photo of the Accutron 114P. It also has a serial number under the grounding strap. This one seems to be very close to the production watch. Note the very minor changes of screw positions on the train bridge plate compared to a production watch pillar plate.

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This coil showed up in a box of assorted 214 bits I got recently. I have seen literally thousands of coils in my time, but never one like this. At first it looks like a 5 point coil with an odd transistor, but it is more than that. The winding arrangement of the coils is very different from any other 214 coil I have seen. This one has the feedback coil in the component coil! The cell coil has only a drive coil, nothing more. I am sure the coil is original Bulova as the unused terminals are unsoldered and never have been (the ground plate on the cell coil), not to mention that the connections to the straps are different also. Both coil sides have ground plates. The component arrangement is similar to an early 5 point coil, except the transistor is a ceramic type used in early mil spec electronics. I have also seen transistors similar looking in balance wheel electric watches from Seiko and Citizen dating from the early 70's. One can only wonder at the motive behind this coil design, perhaps there was a threat to the usual supply of transistors at some stage and Bulova were experimenting with different options. One thing does seem clear though, Bulova didn't appear to waste much that was useable, as we have seen in the overstamped pillar plates from earlier years that were later pressed into service.

Regards, Rob
We know, of course, that Citizen made 218 movements, as well as a 219-like movement. To the best of my knowledge, they never made 214s, but might not this odd piece have something to do with the process of sharing technology & information leading to that production?
 

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On the topic of prototypes, this is the Accutron 114.

A cased up movement found on the japanese watchmaker's instagram. Blue coils!
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Photos from the collector with 20+ 114/114P movements. The movements are stored in little plastic cases.
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