Setting Hands On 7750

[sstakoff]

Just completed my first ETA 7750 service. All went well, but I can never seem to install the chrono hands correctly.

I reset the chrono mechanism and do my best to install the hands pointing right on the number 12. Invariably, when I run the chrono and then reset, the second hand flies back to the 2 or 3 second mark :(

 

Is there a technique that I'm missing, or am I just a bit clumsy??

 

Stu...

[SSTEEL]

Something to note, when refitting the chronograph hands, ensure the stem is in manual wind position, not time setting position.

[clockboy]

The other issue is the hand could be slipping on the arbour when it snaps back to zero. 

[Geo]

If you use the correct movement holder, you can keep pressure on the hammers while pressing on the hands and ensure absolute zero is obtained. Without doing this the hammers are only held by spring pressure and the hearts may move slightly when positioning the hands. Using the correct holder also ensures that you don't dislodge the lower jewels when firmly pressing on the chronograph hands.

[sstakoff]

Geo - this is interesting. I have a 7750 holder - see attached pic. However, I'm not quite certain on its correct use with respect to hand setting. I am not at the bench right now, so I cannot be certain, but I think the automatic mechanism would interfere with the jewel support posts - no???

 

Also - how does one use this (or another) type of movement holder to ensure that the hammers are held in place as you suggest?

 

[Geo]

Fit the hands before fitting the auto mechanism to allow the jewel supports to do their job.

The other movement holder allows you to operate the chronograph as you would when the movement is cased. When pressing on the chrono hands, first run the chronograph, stop it, then zero it, but when you zero it keep pressure on the button and this will keep the hammers pressed hard into the hearts. Now fit the hands and the hearts can't move.

[sstakoff]

That makes sense! To be clear, is it just the oscillating weight that needs to be removed in order to properly use

the movement holder?? Or does the entire mechanism - automatic bridge, etc - need to be removed?

[Geo]

The auto bridge supports chrono pinions, so only remove the balance rotor.

[sstakoff]

Thanks again! Will give it a shot tonight...

[SSTEEL]

Let us know how you get on :)

[sstakoff]

Not looking forward to popping the bezel off this watch again :(

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[sstakoff]

ugh... Didn't go quite to plan. I removed the oscillating weight and put the movement in the holder.

The pushers on the holder don't extend far enough to activate the chrono mechanism :(. I am not

convinced that the movement is properly seated in the holder. It seems to be raised up a bit too much.

I am thinking that perhaps the jewel supporting pins are not adjusted properly. Too tired to risk an adjustment tonight,

but here's what I was thinking:

o Unscrew (lower) both pins

o Install movement into holder - all the way in

o Slowly raise the support pins until the movement moves up just a hair - then back off so movement is fully seated in the holder

 

Does this make sense??

 

I'm hoping others have had luck with this A*F holder. If it's simply not up to doing the job correctly, I'd appreciate some

recommended holders. They are quite pricey, so hoping I'll get the A*F to work. But if I need to spend some money to

get the proper tool - so be it!

 

Stu...

Edited July 14, 2015 by sstakoff

[clockboy]

I had the same issue with the AF holder when working on a Beitling with a 7750 movement. I could not get the chrono pushers to work so used peg wood. I think it depends on what case the 7750 is in.

[Geo]

You're certainly not having it easy Stu. What you suggest is the way to go, plus CB's peg wood solution for activating the chronograph.

[Lawson]

 

I'm hoping others have had luck with this A*F holder. If it's simply not up to doing the job correctly, I'd appreciate some

recommended holders. They are quite pricey, so hoping I'll get the A*F to work. But if I need to spend some money to

get the proper tool - so be it!

 

Stu...

 

Hey Stu,

 

The quality of the holder does make a noticeable difference to the ease of fitting the hands.  A cheap plastic one will work, but a quality metal one is the ticket to success IMHO.

Last week I fully serviced one of my old friends watches.  We both worked in the IT industry for many decades, and I spent time working with him in Papua New Guinea on a project for ExxonMobil.  This watch is his "Ex-Pat" watch ... as we all brought nice watches duty-free whilst working over there on a FIFO (Fly-in Fly-out) contract arrangement.

 

He purchased this TAG Carrera with a "Caliber16" 7750 movement. 

 

 

I used genuine ETA movement holder to set the hands.  It worked very well ... as expected, being a genuine ETA product.

 

 

Setting the hands perfectly really makes a Chrono Dial pop; just as a hand even a tenth of a second out of alignment detracts from the look of the dial considerably.

 

 

The holder is one that I borrowed, and even though I was a good holder, it's not the one I'd recommend.

My recommendation, after LOTS of research, is the Horia Movement Holder.  It's price is comparable to that of the ETA, but as you can see from the pic below, it's even higher again in quality, and can do both the 7750 and the 7753 ... so two holders in one!! 

It's the one I'm saving up to buy for myself.

 

Edited July 14, 2015 by Lawson

[sstakoff]

I've see this holder. It looks like a serious piece of equipment. I was afraid someone would recommend this one!!! Decisions, decisions....

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[sstakoff]

A picture is worth a thousand words!! Thanks very much for all your advice!! The issue with the A*F holder was exactly as suspected - the support pins were too high, impeding the pushers contact with the operating levers.

 

Holding the 4'oclock pusher in was indeed the secret to nailing the second hand and minute register hand alignment.

I did discover that the opposite was true for the hour register. Holding the button in allows that hand to rotate freely. When released, there appears to be sufficient pressure from the locking mechanism to hold the pivot in place for hand installation. Trying the install the hour register hand with the chrono button pressed in will result in similar misalignment issues as I was having with the other hands.

 

Just to clarify - there is no jewel support pin available for the hour register nor for the regular (non-chrono) second hand. I assume the correct procedure here is to apply only enough force to seat the hand. I'd have to look again, but I assume the reason for this is that the jeweled ends for these wheels (4th wheel and hour register wheel) are not visible/accessible on the assembled watch. Do I have that right??

 

Again - thanks to all for making this a successful service.

 

Stu...

 

[Lawson]

Fantastic Stu!

 

Those hands look perfect mate ... and doesn't it give you a great feeling when you nail it :)

[Geo]

Excellent Stu, I think you have it all well worked out now. :)

[DJT2]

Great informative post. Thanks guys, exactly what I was looking for.

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