Wristwatch restoration, servicing and repair

Archive for the ‘Alarm’ Category

Seiko 4006-6031 (17J Bell-Matic)…

I picked up this very sorry looking Bell-Matic with a badly scuffed up case and crystal, and showing all the signs of damaged dial feet. Looking past all that though, the hands, dial and alarm bezel looked great, plus all the original lume was still intact.

(Click pictures to enlarge)

On taking the watch apart I was surprised to find that the dial had a built in spacer. I’ve always assumed that it was only the 700x series of Bell-Matics that had this kind of dial. Sometimes it’s great to be wrong!

As I’ve described in a previous post, it’s possible to replace the feet without soldering on this kind of dial, as the old ones can be drilled out and new ones can be made and fitted relatively easily.

With the main problem solved, a movement service, a new crystal and quite a bit of work on the case finished the job…

Rich


Seiko 4006-6031 (17J Bell-Matic)…

I already have the blue dialled version of this watch, but this one looked too good to miss. Although not running, it showed great potential with a near perfect dial, alarm ring and hands.

(Click pictures to enlarge)

Only a short post this time as there were no hidden surprises with this one. A movement service, a new crystal and a once over for the case was all that was needed to add another great watch to the collection…

Rich.


Seiko 4006-7000 (27J Bell-Matic)…

I rescued this survivor from the bay, the lume looked clean and I hoped that the rest of the dial was in good condition under the damaged crystal.

(Click pictures to enlarge)

Regardless of its condition, the dial was skewed in the case meaning that both dial feet had been broken off, so I knew it would need some extra work.

The good thing about the 700x series of Bell-Matics is that, unlike most watches, rather than having an independent spacer under the dial to provide clearance for the day and date rings, a metal spacer is fixed to the back of the dial instead. This means that broken dial feet can be drilled out, new feet made, and reattached.

When making new dial feet it is important to make sure that they are the right length, as the day wheel is only held in place by a dial washer under the dial on Bell-Matics. If the dial feet are too long, the dial will sit too high and the day wheel won’t be pressed down enough to engage with the day change mechanism.

Here is a picture of a new dial foot in place (and inset is the 0.5mm drill used to remove the old feet alongside a match… small stuff!)

Here’s the watch after the dial repair, a movement service, a case polish and a new crystal, it’s quite a transformation. It’s hard to describe the colour of this dial, in some lights it looks silver and in others it has a blue hue…. in either light it looks good!

Rich.


Seiko 4006-6040 (17J Bell-Matic)…

Up and running again and first in line, another Bell-Matic. This time one of the more popular integrated bracelet models with a great blue dial.

(Click pictures to enlarge)

I bought this one on eBay without seeing a movement picture (I like a gamble!) and was pleased that the movement, though not working, was in decent condition. The watch did have a few cosmetic issues that would need to be put right though, the caseback was wrong (a -6031), the bezel had a large dent in it, and the crystal didn’t fit at all. I also had my suspicions that the hands weren’t right, but I’ve seen this model with several different styles, so I decided to leave them as-is for now until I know for sure.

I had my doubts about the originality of the bracelet too. Though the fit and finish matched the case perfectly, the -6040 is more commonly seen with a different stlye of bracelet. However, a bit of digging turned up this old Seiko brochure which shows a -6040 with the same bracelet, so that was good enough for me.

If you’re looking to buy an integrated bracelet model, it’s worth paying particular attention to the bracelet, as a regular strap can’t be fitted to this style case. Seiko’s stock of replacement bracelets ran out years ago and there isn’t an aftermarket alternative, so you’ll see some real disastrous ‘work-arounds’ out there on the open market.

I knew before I bought this one that I had a good -6040 caseback and bezel from an old parts watch which I could use, so a once over for the movement and a new crystal finished it off.

Rich.


Seiko 4006-7020 (27J Bell-Matic)…

Another 27J Bell-Matic, like the last one, a -7020 model but this time with it’s original bracelet. The watch had been ‘resting’ in a drawer for years but despite being a little untidy on the outside, the movement was in great shape with just a little wear on the edge of the train bridge caused by worn rotor bearings.

(Click pictures to enlarge)

The second hand had been replaced with one that was too long, but apart from that there was little sign that the watch had ever been opened. However, when I removed the calendar plate… Huh? A jewel for the lower mainspring barrel arbor?

As this was one of the earlier Bell-Matics (Nov. 1967) I wondered whether this was a different jewel layout, but as none of the other jewels were missing this had to be an extra. Under 10x magnification I could see that the inside of the hole was not plated, so the jewel setting must have been reamed and pressed in at a later date by a very diligent watchmaker, making this a very rare 28 jewel Bell-Matic, great! (Inset is the opposite side of the jewel with the mainspring barrel removed).

This extra jewel means that every pivot in the timekeeping side of the movement now has a jewel which reduces friction and wear, increasing accuracy. For comparison, here’s a shot of a regular main plate in which the lower mainspring arbor has worn through the plating after many years of use.

Eventually, this wear will result in too much endshake for the barrel. Under the tension of the mainspring, the barrel will then be pulled out of alignment and will not mesh smoothly with the centre wheel, affecting the timekeeping or stopping the watch.

No more surprises… so after a good cleaning, I replaced the worn winding rotor bearings, found a replacement second hand and gave the case and bracelet a light polish. I even managed to clean up the original crystal.

Here’s the result… my 28 jewel Bell-Matic.

Rich.


Omega Seamaster Memomatic…

I’m sure it’s obvious to regular visitors that I’ve got a keen interest in Seiko’s Bell-Matic watches. I’m looking to broaden my knowledge of vintage alarm watches and read about Omega’s Seamaster Memomatic model from the early 70’s, which shares a lot of similarities with Seiko’s Bell-Matic, so I thought I’d compare the two.

Here’s the Memomatic, it’s a great looking watch…

(Click to enlarge – pictures by a.r.a. gallery)

The first thing to point out is that rather than having a separate bezel for setting the alarm, the Memomatic has two discs in the centre of the dial which are rotated via the crown. This allows the wearer to set the alarm to the exact minute, rather than the ‘near enough’ approach used by the Bell-Matic and most other vintage alarm mechanisms.

The adverts from the time show that this was a major selling point for Omega, but looking closely at the service manual, a tolerance of +/-4 minutes is deemed acceptable when testing the alarm triggering mechanism, which makes it no more accurate than the Bell-Matic. Doesn’t this actually defeat the whole purpose of setting the alarm to the minute? Strange!

It has a very similar crown layout and operation to the Bell-Matic except that the alarm time can be set both clockwise and anticlockwise via the winding crown and date quickset is performed by pressing the recessed button between the crowns. The Memomatic mainspring can also be hand wound, the Bell-Matic cannot. (A scan of the full Memomatic user manual can be found here).

The engine in the Memomatic is Omega’s 980 calibre, which has 19 jewels and is slightly smaller in diameter than the Seiko at 30.8mm, (Seiko’s 4006A is 31.2mm) but slightly thicker at 7.8mm (the Seiko is 7.15mm).

It runs at 21,600bph (6 beats/sec) which is slightly faster than the Seiko which runs at 19,800bph (5.5beats/sec). Notice too that, like the Bell-Matic, the 980 has an independent sounding spring around the edge of the calibre rather than the hammer impacting part of the watch case as is common in other alarm mechanisms.

The biggest advantage that the Memomatic has over the Bell-Matic is that it has only one mainspring which powers both the going train and the alarm. As this is an automatic winding calibre, this also means that the alarm never has to be wound independently. If the watch is running, the alarm should be ready to go.

Reading the technical literature on the calibre, when triggered, the mainspring barrel completes one complete revolution which sounds the alarm for 8-10 seconds (about the same length of time as the Bell-Matic). How it manages to do this while still supplying power to the going train is very intriguing to me. Even looking at the exploded diagrams in the service manual it’s hard to work out how it does this.

I’d like to get hold of one and study it in depth but that could be tricky as only 35,000 examples were made and they now change hands for around the US$800 mark. Even when available on the high street, this technology still commanded a hefty price, the Memomatic originaly retailing at a higher price than Omega’s popular Seamaster Chronograph.

I’d better start saving up….

Rich.


Seiko 4006-7020 (27J Bell-Matic)…

This 27 Jewel Bell-Matic is one of the early models from 1968. From a cosmetic point of view, this one arrived in quite poor shape.

(Click pictures to enlarge)

The lume on the hands and alarm pointer in particular needed some attention but luckily, the dial was still in good shape under the scratched up crystal.

The seller said that the watch had a damaged escapement so I was prepared for a mangled hairspring, but this wasn’t the case, the balance assembly was fine. However, when the watch was shaken it ran down instantly indicating a problem with the escapement somewhere. Peering into the movement quickly revealed the problem… no escape wheel, a much easier fix than battling with a damaged hairspring! Thankfully, no other parts were missing so after a thorough cleaning and an escape wheel from the parts box, the movement started right up.

I also found that the hands had been installed without the proper tools at some stage and were bent in all directions. It took quite some effort to straighten them out. Bent hands are always a problem but especially so with Bell-Matics. When the alarm triggers, the hour wheel rises, reducing the clearance between the hour and minute hands. If the hands are in poor condition (or have not been set correctly) they will touch when they pass, either stopping the watch or worse, scratching the hour hand on the underside of the minute hand.

After sorting out all the cosmetic issues, I gave the case a light polish to get rid of any surface scratches and installed a new crystal. Quite a bit of work required this time to make this one right, but a nice end result.

Rich.


The Seiko Calibre 4006…

Another comparison post, this time the 17 and 27 jewel versions of the 4006A calibre found in most of Seiko’s Bell-Matic watches. While the majority of this information can be found by digging in the archives of various forums, I thought I’d highlight the differences here with a few pictures.

The production run for the 4006A calibre is thought to have been between 1967 and 1977 and it was manufactured with three different jewel counts, 17, 21 and 27 jewels. When the watches were assembled, the calibre inside was clearly marked on the watch dial…

(Click pictures to enlarge)

Opening the caseback reveals the first difference between the calibres, the winding rotor is marked with the jewel count, which should match the dial markings if everything is in order.

Removing the rotor and winding bridge reveals the first technical difference, additional jewels for the third and fourth wheel pivots on the 27 jewel model.

(Click picture to enlarge)

Also notice that this particular 27 jewel movement has an extra long sounding spring. The longer spring isn’t fitted to all 27 jewel movements, I’ve only seen it on the really early models. (It doesn’t seem to make the alarm any louder).

Removing the ratchet wheels for both the mainspring and the alarm spring barrels reveals two more of the additional jewels, for the barrel arbors. This side by side comparison of the barrel and wheel train bridges clearly shows all four extra jewels.

The rest of the jewels can be found on the other side of the calibre under the dial and calendar mechanism. The remaining six jewels are all underneath the date ring, embedded into the calendar plate…

While these jewels do reduce friction for the date ring, six jewels for this task is overkill, which makes me think that Seiko may have been planning additional upgrades for this calibre. Here’s a side by side shot of the calendar plates showing the extra jewels.

(Click picture to enlarge)

When I compared the 6106 calibres in a previous post, I found similar jewels under the date ring on the earliest version, the 6106A. These jewels were then used in revisions B & C of the calibre, adding Diafix caps for the third and escape wheel pivots. As the 6106A and 4006A calibres were both introduced in 1967, I wonder if Seiko had similar plans for the 4006A…. a 4006B perhaps?

If a 4006B was planned, it never made it into production, Seiko opting instead to discontinue the 27 jewel version of the calibre in 1974 and finish the production run with just the 17 jewel version.

So, is it worth paying a premium for a 27 jewel Bell-Matic? I think it is. Though technically ‘functioning jewels’, the six jewels under the date ring don’t bring much to the party, but the additional jewels for the mainspring barrel arbor and the third and fourth wheel pivots means that the majority of the going train is now jewelled. This will reduce wear, increasing the accuracy and longevity of the movement. The 27 jewel models were made earlier in the production run, and there are fewer of them, which also increases their appeal and collectability.

I was hoping to include a 21 Jewel movement in this comparison but as they only had a production run of a year or so (1967-68), they are rarely seen. I’ve read that the 21 jewel model has a mixture of the upgrades here, with two extra jewels each for the calendar plate and the barrel and wheel train bridge. I’ll post again when (if?) I get hold of one.

** I’ve since acquired a 21 jewel model, read the post here **

Rich.