Elgin Calibre 725 and 910

If there is such a thing as a common Elgin Electronic calibre, it would be the Elgin Calibre 725. Watches with this calibre, branded “Lord Elgin Electronic“, do turn up our favourite auction site from time-to-time. But as to background information on this calibre, once again I’m indebted to John Runciman, FNAWCC of the Chapter 50 Puget Sound, NAWCC for supplying me with images and information and allowing me to publish them on this web site.

On the 725, John says: They supposedly did a limited test marketing in July 1962 in Chicago. Then from a variety of different sources those watches were all destroyed. The references for the destruction are very reliable but it still leaves us with unanswered questions. The service manual was printed in two versions one for one battery and one for two batteries printed in 1961. In 1962 the stockholders report they show a picture of a different Elgin electronic hinting it’s going to be out soon. Then also on February 7, 1963 a rather interesting letter* from Dr.C N Challacombe who at that time was the manager of R&D and product design watches. Unfortunately like all the letters that he’s done he’s answering somebody but we don’t know who it is. This particular letter the wording is somewhat strange in that he says that “the watch is planned to sell”. Which gives the impression to me that it’s not out yet. He also gives prices of $89.50 in gold filled and $79.50 in stainless steel. What the ultimate aim of $49.50 retail although he doesn’t want to be quoted on that.

*A scan of this letter can be seen on the Literature page.

The 725 and 910 Haul:

It’s the first batch of photos that got me started on my Elgin collection. I’d been trying to win an Elgin 725 on eBay for sometime; I hadn’t got one of these early movements and it was a bit of a gap in my collection.

On one of the watch forums, someone got in touch and offered me a haul of about 7 or 8 Elgin 725s in various states; some assembled, some dismantled, none running. It was a risk, but a deal was struck and I bought them all.

When they arrived, there was only one Cal. 725, the rest were Cal. 910. Although I’d never heard of an Elgin Cal. 910 before, I wasn’t disappointed; the 910 seems to be even rarer than the 725. It was Elgins next evolution of the electronic watch movement but few reached the market place.

The 725 and 910 Calibres:

The research and restoration is underway! First task was to understand the difference between the Cal. 725 and Cal. 910. At first glance, they look the same, but after careful examination, the following differences can be observed (there are probably more):

  • 910 has a re-designed, lighter balance but still retains the balance horn of the 725 and the same hacking clip of the 725
  • 910 has a re-designed coil with mounting screws at each end; 725 has its two screws on the non-horn end.
  • 910 has a re-designed movement plate to support the changed mountings of the coil
  • 910 coil has a more prominent horn (similar to Lip R148)
  • 910 has two contact wires (similar to Lip R148); 725 has a single contact wire
  • 910 has a free-floating diode; 725 has the diode stuck to the coil
  • 910 has 14 jewels to the 15 of the 725
  • 910 train bridge is reduced around the right hand screw to give additional clearance for new insulated wires

Cal. 725 can be found in both gold and stainless steel case watches. Cal. 910, on the otherhand, has only been found in the stainless steel case.

Cal. 910 is very similar to the LIP R148 movement. This is not surprising bearing in mind that Elgin and LIP worked togther in certain aspects of developing the first electric movement. There is some reference to this partnership in the Literature section.

The following are some slightly more detailed photographs of the movements:

Cases, Dials and Batteries:

Cases were either gold or stainless steel. The gold ones come in a variety of styles (see below); some with a battery hatch and some without. The stainless steel cases only seem to be in a single syle and all have a battery hatch. Case style numbers are usually stamped on the inside of the case; serial number are stamped on the inside for stainless steel cases and on the outside for gold cases. In all cases, the movement come out through the crystal.

There seem to be two main dial styles: one for gold cases and one for stainless steel cases. In the case of the latter, the dial was either white or grey with some slight differences: the grey variety has no numerals at the hour markers and has double fluts at 12 oclock. Nearly all my stainless steel case dials show radium burn marks on the dial where the lumed hands have not been moved for decades; sadly, it is impossible to remove these marks. There were also several early prototype dial designs as shown below.

Batteries used were (in chronological order):

  1. Elgin battery: Cal. 725 in gold cases with no battery hatch.
  2. Two button cell batteries: Cal. 725 in gold cases with no battery hatch.
  3. One button cell battery (small): Cal. 725 in gold cases with battery hatch.
  4. One button cell battery (large): Cal. 725 and Cal. 910 in stainless steel cases with battery hatch.

In 3) and 4) above, the dials had a half moon shaped piece of plastic glued to their under surface to prevent the -ve terminal of the battery shorting out on the dial surface. In those cases with a hatch, the battery should be placed with the negative terminal towards the dial.

Restored Watches:

From the collection of parts shown at the beginning of this page, plus the addition of one Cal. 725 in gold case and one Cal. 725 in stainless steel case, I’ve ended up with the following working watches, all keeping pretty good time. In all cases, the original dials have been used; I picked the best-of-the-bunch but some still show radium burn marks.

  • 1 x Cal. 725 in gold case
  • 1 x Cal. 725 in stainless steel case
  • 3 x Cal. 910 in stainless steel case
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