ETA / Valjoux 7750: Non-Stop Hour Subdial / Date Wheel Swap

[firebynight]

I'm about to embark on swapping out a date wheel on a ETA/Valjoux 7750. (Black instead of white to match the dial)

Any tips or pitfalls I should be wary of and take extra care with?

Also, a separate project will be determining why the hour subdial doesn't stop running. It will reset when the pusher is pressed, but then it doesn't stop and just continues running. Any ideas what could be wrong there?

Thank you!

[Rafael]

Don't have any specific experience with an ETA 7750 movement but I think this applies to a lot of movement with date complications - be careful when removing the date cover plates because sometimes the spring is loose and it will want to fly to a place of no return. Same goes for reassembly.

 

Good luck!

[watchweasol]

Hi you may find this helpful should something decide to go AWOL

1075_ValJoux 7750 Pages 8-13.pdf 1077_ValJoux 7750 Pages 19-23.pdf

[Klassiker]

Did some searching and found this. Is your hour counter creeping, or running at the right rate?

 

 

[firebynight]

13 hours ago, Klassiker said:

Did some searching and found this. Is your hour counter creeping, or running at the right rate?

 

 

It's running at the correct rate and resets correctly but then doesn't stop. As though it didn't have a brake or something?

[firebynight]

The chrono hands were a total disaster. There were on so tight I couldn't budget then. Created three massive problems:

1. I slightly bent the running seconds pinion/hand holder

2. Worse, I snapped the pinion for the minute counting wheel  It came right out inside the minute hand tube!

I found on eBay a seller for replacement minute counter wheel for $30. Is that a reasonable price? https://www.ebay.com/itm/New-Sealed-ETA-Valjoux-7750-Watch-Parts-Balance-Fork-Wheels-Pinions-etc/133380243986?hash=item1f0e150212:g:z4AAAOSwn8Jeimn1&var=432805034001

Any ideas how I remove the piece of the pinion that's stuck inside the minute hand tube?!

 

[HSL]

42 minutes ago, firebynight said:

It's running at the correct rate and resets correctly but then doesn't stop. As though it didn't have a brake or something?

The hour-counting wheel should be kept in place by the hour counter lock, but if the hour hammerspring is out off place the hour counter lock can't be locked in place by the hour hammer.
But I have no idea how to remove the pinion from the hand tube

 

[Bauertime]

I have been working on a Chinese clone with the hour counter problem. I know that you need to take the plate that covers the mechanism of the counter off very slowly without disturbing the parts . So you can tell why it's not working. Most of the time the spring has flip over or under one of the levers. I've had to put a small bend in the spring so it's better trapped between the plates. This is the worst designed part of the 7750 movement, if you ask me. I've had to take mine apart 3 times now, to fix this problem. By the way my clone is keeping time to within 2 sec. a day.

[Jimbo1959]

 

You could try pushing the broken pinion  out from the front of the hand, be sure to keep the hand flat though. A small pin may fit the hole on the front.