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A Handy Tip for Letting Down the Power on a 7750

by J.Edwards

Here’s a handy tip for letting down the power in the mainspring of an ETA or Valjoux 7750, without the hassle of disassembling the automatic section, achieved by lifting the click spring out of its seating and disengaging the reverser stop click. Check out the video below for a breakdown of the steps involved.

Via @hermanmayer2

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  1. J.Mitterando
    Posted December 3, 2012 at 8:43 am | Permalink

    THAT is Awesome!

  2. Posted December 5, 2012 at 7:09 am | Permalink

    Happy to share!

  3. Jack Freedman
    Posted December 5, 2012 at 8:27 am | Permalink

    With all due respect to the watchmaker tip, I feel it is a risky maneuver to extract the clickspring from the movement. Doing so could loosen the intended firm fixed position necessary for the correct tension with the ratchet wheel.

    A safer way to release power from the movement is to take a pair of fine tweezers placing one tip at the normal clickspring and the other at the automatic clickspring. Then gently pull both clicksprings away from their respective wheels while, with the other hand, controlling the release of the power with the controlled turning of the crown.

    This I believe is a sound way of letting down the power of a 7750 movement.

    Jack Freedman

  4. Posted December 6, 2012 at 5:50 pm | Permalink

    Thanks for sharing your perspective, Jack. Your concern is a valid one.

    The prongs on the click spring help to hold it firmly in place. If the tip from LWT is executed without due care, I do see how damage could be done. If the task is performed only once every 5-7 years during routine service, I would imagine it would take centuries to wear the plate away enough to cause noticeable harm.

    Letting down the power on a 7750 for final adjustment is something I concede I rarely do myself as I typically start at half wind and then check at full. I shared the tip as I do know several watchmakers who have expressed frustration over it.

    I would encourage you to share a video response of your technique on YouTube for others to benefit from.

  5. Jack Freedman
    Posted December 6, 2012 at 6:55 pm | Permalink

    Working on 7750 based movements on almost a daily basis I come across many which have loose clicksprings requiring tightening. Therefore, removing the clickspring to let down the power only adds to such problems.

    The technique I use and described is simple and straight forward. Regretfully I’m unable at this time to create a video and post it.


  6. Posted December 7, 2012 at 8:26 am | Permalink

    Thank you for sharing your experiences on the 7750 with us, Jack. One of the great benefits of the Internet is the ability to discuss and share information like this among otherwise fairly isolated groups of watchmakers.

    I can’t say I’ve encountered a loose click spring on a 7750 or one of its derivatives before, but I will make a point of keeping an eye out for them henceforth.

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