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Toadtorrent

A7750 - Hands Don't Fit Because of Press-On Shims on Counter Wheels

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Hello Fellow RGW'ers.

 

It's been a looooong time since I've posted anything here...but I have lurked every now and then.  Life caught up with life, and I had been unable to be active on this great forum for quite some time...but now, have decided to have fun with the hobby again, and have encountered trouble I'm hoping some of you can help with. I see my posts and content have disappeared...hmmm...my legacy is gone.  Hah.

 

If you're going to get back in the hobby after doing nothing but enjoying the watches you have, why not do it by trying to learn to do a full service on a broken A7750?  Yeah...I know...I feel the hurt.

 

This is an older, standard A7750 from one of the trusted dealers that had been running fine for many years, but finally died...so I figured I had nothing to lease.

 

On disassembling the movement, I found that a number of the Counting wheels were "permanently" attached to the bridge plates:

  • Minute Counting Wheel on Chronograph Bridge
  • Reduction Wheel on Chronograph Bridge
  • Minute Counting wheel to Barrel and Train Wheel Bridge
  • Second Wheel through whole assembly

 

To hold the wheels on, there were press fit "caps" like below:

20191128-155049-1.jpg

 

I tried disassembling the movement leaving these things on, but right at the start, I was doomed.  Removing the Chrono Hands, resulted in one of the caps coming off of the Minute Counting Wheel as below:

20191128-152659-1.jpg

 

As you can see, the caps actually shim the post of the wheels.  So, when REASSEMBLING the movement, the hands no longer fit.  The problem was that I could not figure out how to reassemble some of the pieces without removing the caps, as the layering of gears was not possible with fixed wheels / gears.

 

Reassembled, the posts on the gears/wheels, without the caps looks like below, and will no longer fit the hands that I have (IWC3717 in case anybody is interested).

20191128-152746-1.jpg

 

Sorry for the long winded intro, but my questions are:

  1. Has anybody seen this before? This really shows why the A7750 is not really worth the time to service...better to just buy a new A7750 for $130 CA...and trust your luck
  2. Does anybody know if this design practice was something done in the past and is now not done?
  3. Does anybody have a guess if my hands will fit on a new A7750, or will I need new hands? (hard to tell from a pic...but I'm trying my luck)

 

Thanks for any help...hope to hear from some of the old timers out there and reconnect!

 

As a side note, knowing that the movement was already not working so there was nothing to lose, and ignoring the fact that I can't get the hands on, it is really cool to be able to takedown and rebuild a movement and get it working.  I have pics ready to go for how to do this...as there were certainly some lessons learned that I didn't see in any of the other online 7750 content I had researched.

 

Cheers,

Toad

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Thanks...ordered those as a backup.  I will remove paint on the red sub hand and repaint...and will also polish them silver.

 

I also realized...I had 2 issues:

1) the post on the counting wheels were one thing that needed to be removed

 

2) the 1st pic above is actually the post on the subdial hand that popped off

 

I am going to attempt to stake the post back on the hand... it I will still have one hand that needs replacement 

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