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ETA Valjoux 7750 questions

Danh

By Danh
in Watch Repairs Help & Advice

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Danh WRT Addict

Danh

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Evening folks 

decided I wanted a project and it was going to building a watch at cost, picked up everything I needed from various places around the planet.

i picked up a 7750 movement cheaply (so expected some surprises as the movement is a genuine Swiss one).

Assembled the watch, and during the process noticed a couple of irregular things with the operation.

I am hoping if I post a list you may be so kind as to point me at what to look for when I disassemble to sort. 

1. When the stem is removed the watch sometimes stays running

2. When the chronograph is reset the hour counter does not reset when the minute and second counter do.

all good fun, and loving the adventure, plus the watch looks lovely with the sapphire back and diver case.

thanks for your time folks :)

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HorologicalHobby Watch Enthusiast

HorologicalHobby

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1: Is this pulling stem out to set the time, or pulling the stem out completely?

If it's the first, then yes the watch should stop if it has the hack (which I believe is standard on all 7750's), however it will keep running if you just pull the stem out completely.

2. That's very weird, could be an issue with the hammer on the dial side that resets the hour function, or it could have a damaged, dirty, or wrongly lubricated hour counter. Do you have a picture of the dial side under the calendar works? 

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noirrac1j Distinguished Member

noirrac1j

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Posted (edited)
8 hours ago, Danh said:

Evening folks 

decided I wanted a project and it was going to building a watch at cost, picked up everything I needed from various places around the planet.

i picked up a 7750 movement cheaply (so expected some surprises as the movement is a genuine Swiss one).

Assembled the watch, and during the process noticed a couple of irregular things with the operation.

I am hoping if I post a list you may be so kind as to point me at what to look for when I disassemble to sort. 

1. When the stem is removed the watch sometimes stays running

2. When the chronograph is reset the hour counter does not reset when the minute and second counter do.

all good fun, and loving the adventure, plus the watch looks lovely with the sapphire back and diver case.

thanks for your time folks :)

You're gonna have to open it up and disassemble.Tha hack  lever should be lubricated with a couple of drops of Moebius D5  on the plate and @MortenS is right: the hack has to be properly seated in its slot and coupled to the sliding pinion so that it does its job when the crown is pulled out.

DSCN0186.JPG

For the other problem...is the hour counter just NOT resetting or is it resetting improperly? If its not resetting check the alignment of the hour counting wheel:

http://www.eta.ch/swisslab/7750/7750.html

 

The hour counter lock, spring, lever and hammer also have to be properly positoned:

http://www.eta.ch/swisslab/7750/7750.html

I know its a bummer to have to take it apart again, but if you want to fix that problem you'll have to.

J

Edited by noirrac1j
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Danh WRT Addict

Danh

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Thanks for all the answers guys, really appreciated, and loads to go on

i have watched Marks Video, but will watch it again a few times (my wife thinks I am strange )

it is a couple of days before I have a chance to do it, but will report back

once again, thank you

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noirrac1j Distinguished Member

noirrac1j

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Posted
7 hours ago, Danh said:

Thanks for all the answers guys, really appreciated, and loads to go on

i have watched Marks Video, but will watch it again a few times (my wife thinks I am strange )

it is a couple of days before I have a chance to do it, but will report back

once again, thank you

Go slowly and methodically....the valjoux is unforgiving.

JC

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Danh WRT Addict

Danh

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15 hours ago, noirrac1j said:

You're gonna have to open it up and disassemble.Tha hack  lever should be lubricated with a couple of drops of Moebius D5  on the plate and @MortenS is right: the hack has to be properly seated in its slot and coupled to the sliding pinion so that it does its job when the crown is pulled out.

DSCN0186.JPG

For the other problem...is the hour counter just NOT resetting or is it resetting improperly? If its not resetting check the alignment of the hour counting wheel:

http://www.eta.ch/swisslab/7750/7750.html

 

The hour counter lock, spring, lever and hammer also have to be properly positoned:

http://www.eta.ch/swisslab/7750/7750.html

I know its a bummer to have to take it apart again, but if you want to fix that problem you'll have to.

J

Love the animations, and the info, thank you

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Danh WRT Addict

Danh

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I have another question before I take it apart if you would be so kind

is it easy to fit a day wheel to the movement? As far as I can tell I need the date wheel, day jumper, day star driving wheel, and a spring (that I have not managed to source yet)?

is this possible? And did I miss anything ?

thanks

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noirrac1j Distinguished Member

noirrac1j

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Before I say "its not hard at all'," do you know how to uncase the movement, remove all of the hands, and remove tge dial? If yes then it'll be easy to change the day and date wheels and all related mechanism.

JC

Sent from my SM-G925T using Tapatalk

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Danh WRT Addict

Danh

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Hi JC, 

Already uncased it, can remove the hands no problem, removing dial is fine (I fitted it when I built it)

i have to strip it anyway to see why the hour counter is not zeroing, so am contemplating adding the day wheel. (And changing the dial of course)

tried googling it and found mixed answers on the subject, so I thought best to ask the experts :)

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Danh WRT Addict

Danh

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I stripped the 7750 today, really enjoyed it, it turned out the Chrono hour counter needed the parts stripping and lubricating as per the specification.

i decided to not fit the day wheel as I wanted to use the red dial I picked up.

great fun project, thanks to all that helped

 

image.jpeg

image.jpeg

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Danh WRT Addict

Danh

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I did not have to strip down that side to solve the current issue.

I am now totally addicted though, so will probably buy a 7750 movement for repair from somewhere so I can do a complete strip and rebuild.

i love the mindfulness of the process

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    • Neverenoughwatches
      Stem removal after fitting hands

      By Neverenoughwatches · Posted

      So leave off the seconds. Stand the movement on its edge, its the dial edge that rests on the pad ( either rubber or cork , something that wont slip ). Use a finger of your left hand to hold the movement upright,  right hand presses the release and flicks out the stem. I do it this way so i can see what I'm under a microscope. But you could hold the movement between two fingers of your left hand, its the right that has to manipulate the stem out by pushing the release and flicking out the stem with  right ring finger nail. Sounds more complicated than it actually is. I guess you could fix a push pin to something solid, then all you need to do is push the release against the pin, leaving your right hand completely free to pull the stem out.
    • HectorLooi
      Battery

      By HectorLooi · Posted

      Try putting everything back together and closing the back cover. I think one of the two springs has to contact the metal casing to ground the casing. So when you press the button, it will touch the contact on circuit board and close the circuit.
    • PeterS
      Stem removal after fitting hands

      By PeterS · Posted

      Yes, the seconds hand is the longest and goes almost to the edge of the dial. I can’t quite picture it how you do it on the rubber pad
    • Murks
      Battery

      By Murks · Posted

      A don't think so it leaked or damaged it because the watch itself works it just the buttons ain't working not connecting with the circuit board have taken more pictures of where the buttons makes contact with the circuit board.
    • Neverenoughwatches
      Stem removal after fitting hands

      By Neverenoughwatches · Posted

      I think what peter means oh is once he has fitted the hands and  checked for  alignment if them and that they dont foul, how does he then hold the movement to remove the stem in order to case up. The dial cannot be laid on a cushion or in a movement holder as the hands will get damaged. This can be quite tricky for a beginner, what i do is  to stand the movement on edge on a rubber pad so it doesn't slip. Hold the top edge with one finger then my dominant hand uses 3 fingers to press the stem release and flick out the stem. See below peter, leave off the second hand as this is the longest and gets caught the most, then fit it once the stem is out. Alternatively place the movement in one of the cup style holders, i imagine this is what they are designed for. They only touch the very edge of the dial.  
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