Jump to content

7750 Part Question


Recommended Posts

Ive been working on 7750s for over a year now and have run across all sorts of variations etc but the lock 2 functions pn 8200 pictured below is a first. Anyone shed some light on it??acf37ae16451ef6e8cd63919cb5fd270.jpg

 

Sent from my SM-G950U using Tapatalk

 

 

Link to comment
Share on other sites

I've never seen one like that on ETA 7750. Is it from a clone?
J
I dont know. I bought a spares and it came off it. Could very well be from a clone but the main plate is def an ETA. It seemed as though it was all original at least as far as I could tell.

Sent from my SM-G950U using Tapatalk

Link to comment
Share on other sites

I can't tell from the pic, but is it all metal? Likely a variant as you already know....all I found was an older Horotec guide with this (33 Var), but yours doesn't have the second cutout:
1614624965_ScreenShot2019-05-29at10_07_29PM.png.e4fef21336c9bf9dd7ca969c619d7d68.png
Its like a flat peice of plastice with a wire sticking out. Appears to be teflon or some soft plastic. I have a clone on the way so well see whats inside it. Thanks for looking into it. I wonder if itll perform as the normal one. I honestly dont see the advantage from a manf standpoint making it this way. It almost would seem like itd be more costly than the stamping that the eta parts are made from so thats why im curious.

Sent from my SM-G950U using Tapatalk

  • Thanks 1
Link to comment
Share on other sites

It may be cheaper to cut out polyethylene  (cheaper than teflon) than to do stamping/grinding metal. It will be informative to see what the clone has, but I did see this on the 'bay so maybe it is ETA:

248220142_ScreenShot2019-05-29at11_54_56PM.thumb.png.a18040db575072d849f569948b0dd7dd.png

Edited by noirrac1j
Link to comment
Share on other sites

I got a 7750 which turns out to be the original made by valjoux before the company was bought by eta. Dosn,t say eta7750 rather val7750. This varient too, came with plastic lever, Dr ranfft tells about the lever in diferent variants, I think the plasic is not a sign of inferior material or clone. Chrome plating is awful and I have never seen a balance wheel move this free in any movement. 

Link to comment
Share on other sites

I got a 7750 which turns out to be the original made by valjoux before the company was bought by eta. Dosn,t say eta7750 rather val7750. This varient too, came with plastic lever, Dr ranfft tells about the lever in diferent variants, I think the plasic is not a sign of inferior material or clone. Chrome plating is awful and I have never seen a balance wheel move this free in any movement. 
Would you mind posting pics for the record????

Sent from my SM-G950U using Tapatalk

Link to comment
Share on other sites

It may be cheaper to cut out polyethylene  (cheaper than teflon) than to do stamping/grinding metal. It will be informative to see what the clone has, but I did see this on the 'bay so maybe it is ETA:
248220142_ScreenShot2019-05-29at11_54_56PM.thumb.png.a18040db575072d849f569948b0dd7dd.png
I agree, however the secondary labor to install the wire is where the cost over run I think would occur as it would have to be done by hand. Anyhow.....it looks like the one I have is in fact an ETA part by your findings. This is good stuff for the 7750 body of knowledge. As always thanks for your input. BTW.....im ready when you are for the next iteration of 3D prints for your project. I posted my thread for the first Bronze CNC run. Im slowly getting up to speed on the CAM programming for the machine in fusion 360. If the machine will do what I think it will do we'll have metalic options at least in soft metals such as bronze.

Sent from my SM-G950U using Tapatalk

Link to comment
Share on other sites

1 hour ago, noirrac1j said:

So many watches, I sometime slose track of what I've overhauled, but I keep good records....I HAVE worked on a Valjoux 7750 with this same plastic part. It was a Lorenz chrono:

reassemble_00001.pdf 2.54 MB · 2 downloads

reassemble_00002.pdf 3.24 MB · 0 downloads

reassemble_00003.pdf 3.75 MB · 0 downloads

so it's the same as in my movement.....

s-l1600c.jpg

Link to comment
Share on other sites

2 hours ago, bjd1020 said:

I agree, however the secondary labor to install the wire is where the cost over run I think would occur as it would have to be done by hand. Anyhow.....it looks like the one I have is in fact an ETA part by your findings. This is good stuff for the 7750 body of knowledge. As always thanks for your input. BTW.....im ready when you are for the next iteration of 3D prints for your project. I posted my thread for the first Bronze CNC run. Im slowly getting up to speed on the CAM programming for the machine in fusion 360. If the machine will do what I think it will do we'll have metalic options at least in soft metals such as bronze.

Sent from my SM-G950U using Tapatalk
 

Great information to have on the 7750. I am going to test a piece of curved plexi for the crystal and also have to try the drill holes for the stem/crown. I'll let you know when I get all that sorted out. Thanks!

J

  • Like 1
Link to comment
Share on other sites



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • Hello everybody, sorry for the late reply. Thank you all so much for your help and your tips. I got lucky and found a replacement wheel bridge for cheap which actually ended up being in decent condition. I decided not to do anything about the mainspring barrel pivot since I didn't have the right tools and the barrel didn't have much endshake anyhow. I am happy to report that the watch now runs great, I have regulated it to about +-10/s day which is fine by my standards. The timegrapher result looks decent as well, although beat error is around 0.6ms which could be better I suppose. Amplitude reaches over 230 quite consistently which I'm happy with also. My lighter fluid has also been replaced by balance spring cleaning solution and now the springs don't stick to themselves anymore - who would have thought. I'm super happy with this watch, it might not be worth a whole lot but it's awesome that I could restore it and it makes me wear it with pride. To me it's a genuinely good lucking watch, it'll be my daily driver for a while. Thanks again to everybody for their input! I couldn't have done the repair without your help.   Here are some images for those interested, the bracelet isn't original but I don't really mind:    
    • Balance-hairspring system is oscillator with big Q-factor. When all in the movement is OK, the rate (frequency) is verry close to the own resonant frequency of the balance-hairspring. But in some cases, the movement (with foult) will force the resonator to work on pritty different frequency, sometimes faster, and sometimes slower. When this happens, the amplitude is always weak. So, the first thing to ask is what is the amplitude. If it is more than 180 and the hairspring doesn't touch itself and anything else, then for sure it is 'short'. If the amplitude is weak, then the first thing to do is to understand why and rectify the problem. At this time no point to check timekeeping. But, if one doubts that the hairspring is not correct, then He needs to calcullate the rate of the movement, then to 'vibrate' the balance-hairspring out of the movement and to measure the free oscillations frequency (period) with timer in order to ensure that they comply with the rate. If we have pictures, then it will be easier to tell something about that wheel.
    • So much work has gone into this! Thanks again @Jon. I will go back and check my adjustments from last weekend. A few questions for you, if you don't mind. In the reset position, I can understand the problem if the gap between the hammer and the minute counter heart is too big (slide 77) but what is bad about both hammers being in contact with the cams (slide 76)? I read somewhere that Landeron recommended grease on the runner cam, but the minute counter heart should be dry. Is that so, and why? How many tads in a ligne?
×
×
  • Create New...