Chrono Second Hand on Zenith Class El Primero Cal 400 Not Resetting Properly

[FusionTimer]

Hello,

From what I can find on multiple online forums, I get the impression that fitting a chrono second hand on a mechanical watch is as simple as putting the hand back like the others, but I also read (not movement specific) that there's a special way to do this in order for it to reset correctly.

My issue is with a Zenith Cal 400 in a Class El Primero. I re-lumed the hour and minute hands, and after putting them back, the chrono second hand isn't resetting to the 12 o'clock position. Is there a special process I need to follow to fit the chrono second hand correctly?

Any assistance you can provide will be greatly appreciated.

Thank you in advance!

[jnash]

Did you ensure you had the pusher down when you set it? If not it's going to reset to the same place which isn't 12.

Also if it's not the same place every time then I would look to see if the hand is now loose. It needs to be a tight fit in order to stay in the same place when reset die to the sheer amount of force a reset produces .



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[FusionTimer]

I didn't do the pusher part because I didn't have a way to hold the watch securely while setting the hand and pushing the pusher at the same time. Would this be the reset pusher or the start/stop pusher?

As for the tightness, it's still very difficult to remove the hand, although I am not sure if that means it's fit tightly. What's the best way to test this?

Thank you!

[JohnR725]

the problem with chronograph sweep second hands is they have to go on really really tight.. This is because when they returned to zero there is a whole lot of force put on them. So if they are not super tight and they return the zero they tend to wander around..  this means  when pushing at hand on a lot of force is required you have to support the backside  otherwise you'll knock stuff out of alignment on the backside..

Then usually when putting chronograph hands-on if you want them to be in the zero position  as pointed out above you usually have to hold the return to zero button firmly in place  so the heart-shaped cam is locked in place at zero..  otherwise when you push the return to zero depending upon the mechanism a lot of times a return to zero but it will lift off that means we putting the hand on if you turn at all it's free to turn.

the preferred  for putting their hands back on especially the sweep second is a special movement holder specific for this watch. It will support the backside so nothing gets knocked out there and it will have a return to zero button

59 minutes ago, FusionTimer said:

From what I can find on multiple online forums, I get the impression that fitting a chrono second hand on a mechanical watch is as simple as putting the hand back like the others

I like the word simple obviously anyone who told you was simple to put a chronograph sweep second hand on  has never done it before..

 

 

[jnash]

I didn't do the pusher part because I didn't have a way to hold the watch securely while setting the hand and pushing the pusher at the same time. Would this be the reset pusher or the start/stop pusher?
As for the tightness, it's still very difficult to remove the hand, although I am not sure if that means it's fit tightly. What's the best way to test this?
Thank you!

Pushing the reset down will ensure the pinion is in the reset position , not holding it means you can push and move it so it might not be in the correct position when you reset it

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[FusionTimer]

Thank you all for the info!

One other question, maybe I’m thinking too much about this, but I see two ways of holding the reset button:

1. Start and stop Chronograph, then press and hold reset, and fit the hand.

2. Chronograph is already reset, press and hold reset and fit the hand.

Which is the correct way?

[jnash]

I would say First way as you feel the full reset and know it's nots going anywhere as you haven't lift your finger back up

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