Valjoux 7750

[Moose]

Hi all.

i have just acquired a fixer-upper, 7750 based chronograph. It has a Valjoux 7750 in it - as in - a pukka Valjoux badged version. Basic question is - is it likely to be much different from the ETA version? 

Im guessing not, to the degree that a standard ETA 7750 service manual will do the job.

it does not look to have too much work needed, at first glance anyway: The hour recorder does not reset, rotor does not seem to wind the mainspring, but most of the visible winding gears seem to be turning, manual winding is fine. Chrono starts, stops and resets OK ( but not the hour recorder). Timekeeping runs fast, but this seems typically indicative of a visually very low amplitude balance, most likely due to lack of servicing. Otherwise a bit of corrosion on the regulator and not much else.

this will be my first 7750, so looking forward to the challenge.

[bjd1020]

Hi all.
i have just acquired a fixer-upper, 7750 based chronograph. It has a Valjoux 7750 in it - as in - a pukka Valjoux badged version. Basic question is - is it likely to be much different from the ETA version? 
Im guessing not, to the degree that a standard ETA 7750 service manual will do the job.
it does not look to have too much work needed, at first glance anyway: The hour recorder does not reset, rotor does not seem to wind the mainspring, but most of the visible winding gears seem to be turning, manual winding is fine. Chrono starts, stops and resets OK ( but not the hour recorder). Timekeeping runs fast, but this seems typically indicative of a visually very low amplitude balance, most likely due to lack of servicing. Otherwise a bit of corrosion on the regulator and not much else.
this will be my first 7750, so looking forward to the challenge.

Ive been working 7750s for a year now. Ive rebuilt 3 so far. 1 from almost scratch. Im no expert but i have just about every peice of tech data out there and tons of spares if youre looking for anything. Youll get just about all the expert help youll need here. A lot of very experienced and generous folks on this forum. You def come to the right place. Please keep us posted....

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[Moose]

Thanks for the encouragement. I left it running overnight and timekeeping is actually OK. So I guess it just had not run for a bit. It still has a very low amplitude ( under 200) so certainly a very sticky and gummed up gear train. Activating the chrono virtually kills the amplitude and it runs, but not reliably. Again, likely just gummed up and needs a good clean.

The hour recorder runs all the time and won’t reset, so that’s something I need to investigate. Hopefully I’ll find out what the issue is during the strip down.

I’ll likely start getting it stripped down next week, checking for damaged parts and ordering up spares for anything too far gone (the fine adjuster on the regulator looks too far gone with corrosion), and I’ll likely order a new barrel complete, rather than strip and clean the old one.

I think I might do a set of photos, at least for my own benefit, as I have been meaning to do a “before and after” sequence on the last few watches I have done, but just never got around to it. So before I start stripping it, I’ll write these initial observations down as part or the before and after “story”.

[HSL]

10 hours ago, Moose said:

i have just acquired a fixer-upper, 7750 based chronograph. It has a Valjoux 7750 in it - as in - a pukka Valjoux badged version. Basic question is - is it likely to be much different from the ETA version? 

I'm not shure of this statement but there are some obvious differences.
1. The original was a 17 jewel version.

2. As NickelSilver correctly in an other thread reminded us about, the rotor Before ETA has a slightly different design on the Valjoux.

Otherwise you probably can go on with the ETA technical sheet and spareparts.
Good luck and keep us updated!...

[bjd1020]

Thanks for the encouragement. I left it running overnight and timekeeping is actually OK. So I guess it just had not run for a bit. It still has a very low amplitude ( under 200) so certainly a very sticky and gummed up gear train. Activating the chrono virtually kills the amplitude and it runs, but not reliably. Again, likely just gummed up and needs a good clean.
The hour recorder runs all the time and won’t reset, so that’s something I need to investigate. Hopefully I’ll find out what the issue is during the strip down.
I’ll likely start getting it stripped down next week, checking for damaged parts and ordering up spares for anything too far gone (the fine adjuster on the regulator looks too far gone with corrosion), and I’ll likely order a new barrel complete, rather than strip and clean the old one.
I think I might do a set of photos, at least for my own benefit, as I have been meaning to do a “before and after” sequence on the last few watches I have done, but just never got around to it. So before I start stripping it, I’ll write these initial observations down as part or the before and after “story”.

What type of shock system is it?

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[Moose]

To answer a few questions and make notes as I go...

The shock system looks to be standard Incabloc, in that it has the normal lyre shaped shock spring.

The plate has the VAL logo under the balance and 7750 to the left of that near the escape wheel. Interestingly it also has stamped text as a 25 jewel movement. I’m not sure that ALL Valjoux movements were 17J, only the first incarnation of it, later models being 24J or 25J.

Anyway, I wore it all of today with no issues (other than those stated) and timekeeping was accurate enough over the day, only gaining a little.

So - for now its back in the box until next week as I am away now until Monday. Then I will start do document the disassembly and not any faults / issues found, prior to cleaning and ordering of any needed parts.

As another question before I start. As I am new to servicing  7750, I have glanced at the ETA service instructions and noted some very intricate settings, clearances and tolerances being applied to certain parts. In practice - what is recommended by you guys, without purchasing feeler gauges etc. With regards setting up these items? Or do you really need to properly measure and adjust?

TTFN.

Regards - G