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For prisoners of flu, some watch fettling.

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For prisoners of flu, some watch fettling.

Old 28th Apr 2020, 03:19
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For prisoners of flu, some watch fettling.

Two hours of my life I wont get back. Ho hum. Just started fettling again after a long break in which my brain didn't want to do anything except drink wine.

I get the watches out again, and have a fiddle. Boxes of them.

Seiko 7A28, the one without the day date. A lot easier to work on. Here's one. Look good to get my hand back in.



I wish I could buy them at that price now. A no-go gold one like that would make over 100 quid now. Still, this one was cheap, can't grumble it's got no little hands and doesn't go.

The 7A series have four synchronous motors. Each drives its own gear train. The watch has several build layers and is fairly challenging for someone with a brain, but obviously trouble for someone that's lost his mind.

Take out back plate, circuit (a wafer most of the diameter) the COILS. Darn only one of the four is continuous. I have never succeeded in repairing one, and believe me, I've tried. Darn.
It's been in a box in bits through two house moves so carefully count the bits. I'll rob the hands, BUT Horrors! The tiny stem on which the hand is pressed is snapped off on its shoulder. Okay, I've been threatening going in deeper, now's the time.





See the flat plates with jewels in, well it's the one at the top left. Top plate off first. Now down to that little fella.





It's now pointing bottom right. Top plate and target plate gone leaving some wheels (cogs) But, see that tiny round thing in the hole in the C shaped bar on the right. Well, that's one of the motors and it is ferociously magnetic. I pull the shafts while trying not to breath on a single screw. The shaft to the hand looks okay. It's then that it dawns on me. I've turned the watch over trying to memorise the angle and goofed. Totally. It's the wrong motor and shaft. What's more, the shaft came out first and there was no need to remove the motor.

Putting plates back on is hard. Not one hair, or fleck of dandruff. All shafts up through the jewels at the same time. The trouble is, the magnetic one has a mind of its own. It's hooked to any ferrous metal and the Universe at the same time. It flops one way or the other, hard over, never upright. This armature will fit under your fingernail. AND IT'S THE WRONG ONE!

What's more, swearing is not allowed. I decided right at the beguiling, If you lose cool with a watch, It's a tad different to a Perkins Diesel.

The plate is the stator, it has to be slipped over those stanchions while keeping the armature in place and the bottom shaft poked into the bottom jewel.

Well, I wanted a challenge. Tomorrow, I'd do the one I should have done tonight. I could have glued the needle on, but Honest Rob's watch sales would never be the same again.

Last edited by Loose rivets; 28th Apr 2020 at 03:33.
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Old 28th Apr 2020, 07:42
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I saw your endeavours and a long dead nightmare rose like the mist over a graveyard. Following a job interview for the position of computer engineer at IBM, I was invited back to assess my ability to wield a screw driver, allen keys, and a tiny wrench. The target was the guts of an infernal mechanical accounting machine. Pointing at a tiny gear embedded at the centre of the unit, the technical assessor said, "disassemble the unit by only removing the parts that are necessary, and place the gear on the table. There is a time limit but you will not be told what it is".

No pressure then?.

I got the gear out fairly quickly but I had removed one screw too many, the bod said, now put it all back. It was hot in the room, sweating like a pig, I got it almost back together apart from the last retaining screws, and then the bod said - "times up."

A few days later, I was offered the job, The practical aspect had been nothing to do with mechanical aptitude, but everything to do with performing under pressure.

I declined their very generous offer, went elsewhere and never regretted my decision, but the exercise was a very important learning experience.

IG
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Old 28th Apr 2020, 08:07
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I also work on watches as a hobby (and sometimes for money) but usually on mechanical stuff.

With the llockdown I've dug out some watches I've put away for a rainy day and am slowly making my way thru them.

Anilv
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Old 28th Apr 2020, 08:37
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I see your "infernal mechanical accounting machine" and raise you an IBM Golf ball Typewriter, British Rail used them in their marshaling yard porta cabins, and the ash from the tracks used to get into the works, oh and did I forget the IBM 96 column card punch, again the ash would jam the inter-posers thus destroying a whole train load of cards. I very quickly learned my mistake got out and found me a job in a nice shiny DEC computer centre.
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Old 28th Apr 2020, 08:41
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I like doing horology but it winds me up!

This was the last complete strip and re-build.
It's an old Sekonda Hunter.
My eyesight isn't what it was though which gets in the way of the fun rather.




Fascinating watching a master at work...

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Old 28th Apr 2020, 08:48
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Fascinating to see what makes some of you tick...

Originally Posted by Anilv View Post
I also work on watches as a hobby (and sometimes for money) but usually on mechanical stuff.

With the llockdown I've dug out some watches I've put away for a rainy day and am slowly making my way thru them.

Anilv
Certainly a rainy day today though perhaps not in Malysia.
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Old 28th Apr 2020, 09:33
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I did a complete reset on my old Citizen skyhawk as I had lost the timezone LON. Donít know where itís gone, just disappeared altogether so now using UTC. Good accurate timepiece though.
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Old 28th Apr 2020, 09:54
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I've always admired those who have the skill and patience to mend clocks and watches. Anything needing attention from smaller than a 10 mm spanner is getting a too delicate for my stubby digits!
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Old 28th Apr 2020, 12:55
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Originally Posted by cliver029 View Post
Imagegear
I see your "infernal mechanical accounting machine" and raise you an IBM Golf ball Typewriter, British Rail used them in their marshaling yard porta cabins, and the ash from the tracks used to get into the works, oh and did I forget the IBM 96 column card punch, again the ash would jam the inter-posers thus destroying a whole train load of cards. I very quickly learned my mistake got out and found me a job in a nice shiny DEC computer centre.
Serious stuff you encountered there - reminiscent of the infamous Univac 1004, designed to operate in US Carriers and do stock control.
Matey doing the weekly maintenance, runs a deck of cards through the reader punch. Full program deck, in strict numerical order, goes through and matey says "Where is the stacker?"

Says Moi, there at the front - (Empty) I says have a look inside - Opens the access panel - 2000 cards fall out except the ones which were mashed to shreds by the mechanicals.

Ohhh happy days..

IG
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Old 28th Apr 2020, 13:13
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I think that there are things that are sent to try us. And as I get older, I have decided to try less. ...................Rebuilding an ancient Timex is one thing. Re-building my posh wristwatch to-day just can't be done at home.
Ditto with cars. Re-building a Morris Minor, no problem. Work on an old Lotus Elan, much more stretching. (My balancing of a pair of Weber 40s was more luck than science.) Work on a modern car with all those pc.s built in - not going to happen in this house!
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Old 29th Apr 2020, 00:59
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I did my E-Type's three SUs by monitoring the plug colours over extended periods. Just needed an artist's eye.

The watch I showed was much easier than the Rolex. I have a feeling he's done one before. What I can't understand is why it was being cleaned. Mobius oils are supposed to be stable for years and that watch looked like it would have been better off left alone, but I suppose it was a demonstration. I also wonder about the use of metal on wheels - which is what we have to call cogs. I suppose he's got the finesse of an eye surgeon, but I'd be easier with soft copper if not a modern composite.

A lovely man in the US chatted about ham-fisted people changing batteries in watches. He got onto a story of a Rolex course in which the Rolex agents had to time a test watch at different temperatures in a class of mature men. Suddenly one stood up, walked with the watch to the front desk, made all sorts of strangled frustrated noises, and threw the watch into the bin. He stomped out, leaving his tools behind. One chunk of change. One screwdriver can cost $150 if you splash out.

I grind my own with one of those clamps with two little wheels. It's not possible to do it without some device. Also, the tip is not supposed to bottom-out. Also, there's often a convex bottom to the groove, so if it does bottom out, skidding is inevitable.

Sticking the pokey thing in to release the winder. On my Seiko type, it's not unknown to find a tooth off a wheel because the wrong hole has been prodded. Mmmm . . . must eyeball my 7A28's wheel for just that. They can be turned. To change that wheel requires the removal of the main bridge. IIRC, that's seven stems to locate into the jewels and holes, including an armature. I have never tried, but fully intend to test my skills by doing so, given half a reason. I'm not totally convinced I'll succeed, but it's a challenge that prods at me.

On a wonderful site I've mentioned before, 7A38 - by the numbers, one 'Sir Alan' succeeds where other mortals fail. One poor soul tried for hours, and then came back to it another day, and again, and again. I admire his determination. The owner of the site has what I'm sure is the best collection of the 7AXX range in the world.

I found that just plonking my S 6 phone on the eyepiece of my old Watson microscope gives utterly fantastic results. Much better than the Nikon extenders I bought from afar.




Main Bridge with arrow to that motor's armature. This has two of the four coils on board and is an unrelated job.

Sometimes they put them in a posh case. This was obviously the one James Bond wore when off duty and wanted to impress Carole Bouguet.



Last edited by Loose rivets; 29th Apr 2020 at 01:18.
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Old 29th Apr 2020, 14:59
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Here you go loose, enjoy

https://www.key.aero/forum/historic-...being-restored
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Old 29th Apr 2020, 15:35
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I stripped and fixed my 1984 Seiko 7A28-7120 a couple of years ago, fitted a new crystal and seal, cleaned and freed up the stuck pushers, fitted them with new seals and circlips (one went "ping" when I took it apart . . ) and fitted a new strap. It has kept perfect time since I was first issued with it, just needs a battery every couple of years. The only remaining problem with it is that the sweep chrono second hand is now intermittent, almost certainly a problem with its coil or, perhaps, the coil connection. I keep meaning to take it apart and have a go at fixing it, but I so rarely ever need the chrono function now that I've just never got around to it. These Seiko 7A28 movements are remarkably well made, really nicely engineered.
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Old 30th Apr 2020, 15:19
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If I may, can anyone recommend a (mail order) source of good quality 1mm diameter punches?

I need one for the strap pins of a Tissot watch I have but cannot find a punch that thin.

Thanks.
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Old 1st May 2020, 03:24
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In haste. I've been fettling for four hours tonight. I've a lot to learn. I now have made the day date slip over smoothly, but if the watch time itself does it, It's out of phase. Four layers plus hands to get at the day date rings. First bash with a 7A38.

I was going to rob some parts out of a black 7A38, but it's too good to ruin.

VP does the stuck hand twitch with the seconds?
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Old 1st May 2020, 06:30
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Originally Posted by Loose rivets View Post
VP does the stuck hand twitch with the seconds?
No, it's the sweep hand, so only runs when the stopwatch is running, and it doesn't seem to twitch. When setting the chrono hand positions I've occasionally been able to get it to move, but now it seems stuck at 1 second past the 12 o'clock position. I suspect that it's coil may have an intermittent open circuit, and that the slight jarring when trying to use a pusher to increment it sometimes results in the coil making a connection. These coils are so delicate that I suspect the solution is probably to partially strip the watch and replace that coil.


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Old 1st May 2020, 09:02
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Originally Posted by ShyTorque View Post
I've always admired those who have the skill and patience to mend clocks and watches. Anything needing attention from smaller than a 10 mm spanner is getting a too delicate for my stubby digits!
I am much the same ST - I am happy with a big hammer and GS screwdriver (if at first you don't succeed - get a bigger hammer).

Thankfully my £5 Casio's do not require any fettling,if either the battery or straps fail - I just buy a new one LOL
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Old 2nd May 2020, 00:09
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The 7A48-5000 series has 7 hands plus moonphase, so rather testing to work on.





A recent one turned up with a home made circlip. The dirt under the pusher is typical and impacts so it won't work the switch.


I was surprised to see the Rolex guy using plastic and blades to remove the hands. It's exactly what I do, after having one ping of and vanishing. (the skinny chrono one.) I called to the Rivetess for help. 'Don't come in!!!! But can you see a second-hand in my hair?' She said something, or maybe just growled. The hand was on the bench undamaged.

VP, I doubt the coil has failed if it makes any attempt to progress. As you say, the wire is delicate. I would say it's as delicate as glass. Horrible, and the reason my above nice watchmaker advertised for folk not to let just anyone change watch batteries.

I have spent ages trying to repair them. As you've probably noticed, the wires are glued onto the contacts with blobs of transparent stuff. What astonished me was that the wire is partly ferrous. The resistance is ~2k ohms for the short two and ~2.2 k ohms fro the longer ones. Since the termination PCB is so small, one slip when measuring can be fatal.

The black 7A38 that I was going to rob for parts has one coil O/C. There is one blue spot on the centre of the winding so I'll try to bypass that. I never have concluded what insulation coating the wire has so the blob of conductive goo one can buy would be no use without getting to the metal. The metal is destroyed by a soldering iron. I'm sure you know, conductive goo is not approved by most electronics bods so would be a bodge.

You could be lucky with lubing the centre shaft under that strange finger leaf spring. I've recently got a chrono-hand free with that. Odd though, it's one of the largest jewels in the watch, so shouldn't be so critical. One of the 30 or so I purchased in Texas had a bright blue blob on one of the wheels. It was the size of a grain of sand and very hard. I'd made a chisel out of a needle and put it in a cheap screwdriver handle. That worked. It's been a fantastically handy tool. (oilers, I cut the eye of needles down to a Y and polish them with jeweller's rouge. )

I remove that leaf spring and replace the screw while working as it's so vulnerable.

The great thing about the 28 is that it's a lot less complex than many other variations. Unlike the 38, the clutch on the winder stem has only one part. DON'T LOSE IT, they can come out once the green plastic layer is removed and are hen's teeth. As is the timing contact gull-wing thing. One breath and it's gone. Best to work with leaf spring gone and winding stem in place.

Corrosion is like a disease with the electronics. The circuit in this one is beyond hope. That blue or green build-up spreads under the coating.

I'll try to fine the extreme macro I have of a blob. This one was one of three coils O/C in the gold watch I was working on. You can see both wires were broken. Even the good coil was dented but remarkably continuous. This is the watch with the accumulator seconds stem snapped at the shoulder.




Found it. Gasp. It's a 5000 sold declared as a battery leak.




This was taken through a Watson microscope. The blob of green is about half the height of the surface mount capacitor. I assume capacitor, as it's near the battery and across the + and -

Last edited by Loose rivets; 2nd May 2020 at 00:51.
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Old 4th May 2020, 22:05
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Getting that transparent wire connecting blob off was very difficult. I milled it with a snapped .5mm drill. What is incredible is that for the first time ever, I've got a reading from one contact to the end of the broken wire, which I've manage to unwind a few turns.

All I've got to do is A. get the insulation off without breaking the wire and B. fix it on the print. The former is worse than B.

Ewwww . . . I've only just noticed I touched the other blob. Touch that inner wire and it's all over. It reads 2.6k ohms not 2.2 I said earlier. I knew I'd miss-thunk it, as the Admiral would have said.







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Old 15th May 2020, 03:05
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I repaired that coil. Total time about six hours. I'd spent days in Texas trying to find solutions. I used low temperature solder with the iron turned well down. I managed to clean the wire by abrasion - about the amount you'd use on an optic nerve. I got a fairly neat blob much much smaller than the head of that pin but then I had to support the wire. It's so fragile that it wouldn't tolerate bending. I drew out a length of bathroom silicone sealant about 3mm long and as thin as a hair. It's lying along the wire to support it. Nowhere near testing yet.

Oh, why not? I hear you ask. Because I let a little brass ring ping into the air. Twice. Second time cost me about four hours of detailed searching. I left my clothes in the den and resumed in the bright afternoon sun. Finally, I found it, sitting just where I'd expect it to be. It must have fallen off my soft slacks on the third time I searched every stitch crevice in them because the little C of soft metal was where I'd rubbed my hands a hundred times. My pal said, walk about in bare feet. Hmm, the fact is, I can barely feel it with my fingertips.

There are some superp pictures of another date day project by an expert. 7A38 - by the numbers, Forum Tech tips and tinkering How to set the day date. I've learned most of what I know from that site. I don't have permission to uplift photos but its well worth a look if this hobby has piqued your interest.
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