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Repairing when you manually wind and the rotor spins (7750)


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I have tried the ETA reversing wheel in two watches and works perfectly :D

Francisco

Fantastic!

Do you have the feeling that it gives a smoother winding to the watch when you compare with an average working a7750 rev. wheel?

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That is great news!! Do you know offhand if the watches were of the same model? I know Watchdog has said he's seen so many variants of the A7750 movement and I have seen posts that this movement is made in a number of different factories, so I'm wondering if any variances in whether the ETA RW fits, might be due to the particular movement used by a particular factory.

In other words, are there some factories whose choice of A7750 movement appears more probable to fit versus others?

I know this is a very hard answer to give, given we have no idea which variant of the A7750 we are getting in our watches.

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Someone must have changed the specs of the A7750 somewhere along the way...

I tried the reversing wheel in a number of A7750's and they would not fit, the ETA pivots were too large. I did machine down the pivots and made it work, but the amount of time needed to do the mod was too high.

ETA parts are not cheap, the last time I bought a reversing wheel, my cost was almost $40...

Good news, but that's only part of the problem, the transfer gear that directly connects to the mainspring gear is also a problem, it's the one that gets damaged and the teeth stripped when you handwind, as far as I know that one is not interchangeable with the ETA.

Good work Francisco.

RG

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Someone must have changed the specs of the A7750 somewhere along the way...

...and you know what's going to happen R, just when you adjust to the new ability to use some ETA parts...the design will change again, or a new supplier with new specs will change the way things work, and confusion will pop in again.

I'm sure all the factories are ISO 9001 certified, they're just consistently using different standards. ;)

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Watches I tried:

Chopard Chrono limited 2007...the grey dial.. OK.

HBB... OK

Cost of the part... 6 pounds + tax+shipping.

Manual winding improved a lot...so smoothly now...

I checked the dimensions of the asian and swiss RWs...so similar.

Francisco.

Edited by Francisco
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I did a check of a number of A7750's I have in my stock, and none of the ETA parts will fit...the pivots on the ETA wheels are bigger than the jewel holes on the Asian movemements.

Very strange indeed, you must have a different version of the A7750 in those watches.

I also tried the Ratchet Driving Wheel (pn 1482) and it will not work.

Can you confirm that you are installing the Reversing Wheel PN 1535 into these movements.

Thanks

RG

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I did a check of a number of A7750's I have in my stock, and none of the ETA parts will fit...the pivots on the ETA wheels are bigger than the jewel holes on the Asian movemements.

Very strange indeed, you must have a different version of the A7750 in those watches.

I also tried the Ratchet Driving Wheel (pn 1482) and it will not work.

Can you confirm that you are installing the Reversing Wheel PN 1535 into these movements.

Thanks

RG

I will upload pictures and info later..

Francisco

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I just did a double check, and the reversing wheel does fit the 28.8K Asian models, it doesn't fit the earlier versions.

The cost of an ETA reversing wheel for me is $40...when you add this to the cost of the full servicing, it is pushing the limits of value for the money...

I can't think of one occasion where I would have needed to replace this gear with the ETA one, it's the other gear that always gets damaged and stripped and that the ETA part is not interchangeble.

RG

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  • 3 months later...
  • 4 months later...

Help I'm having a problem getting the oscillating pinion back in after it came out. Do I need to disassemble the watch further, like take out the chronograph wheel? or should I be able to place it back in with just the bridge off? Everytime i put it down it never centers properly to align with the lower wheel.

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Help I'm having a problem getting the oscillating pinion back in after it came out. Do I need to disassemble the watch further, like take out the chronograph wheel? or should I be able to place it back in with just the bridge off? Everytime i put it down it never centers properly to align with the lower wheel.

Some advices.

Stop the watch. It is extremely difficult to do it if the watch is running.

Use a strong lamp top see the bottom jewel...

Anyway, it is not easy.

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  • 3 weeks later...
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Post resurrection time,

 

I just made a second attempt at open heart surgery on my most beloved rep, my grey Skyland Avenger V2 to replace the reversing wheel as it had all the symptoms noted here on both winding and lack of power reserve. Thanks to Hazz37 I picked up a reversing wheel from an old scrap movement and swapped it in using the Rodico as a mount guide and protection for the chrono clutch, a second piece was used to hold the hammer in place.

I say Rodico, but in truth I actually used Blutack which was spot on left no residue and was pliable enough without being hard.

 

The bridge slipped back into place and as I gently screwed it down I made sure the hammer was seated and the chrono's were zero'd and that the watch both ran and would wind, then nipped up the auto-bridge fixing screws re-attached the rotor and finally know that the auto wind is functioning once again!

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