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Faulty Seiko NH35a, any guess?


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Hi everyone,

I am digging into mechanical watches internals because of a faulty Chinese submariner clone that I want to repair.

I have disassembled the whole watch and I think the problem is in the pallet fork. Entry pallet seems too short although it seems OK from the pictures:

20201025_153316.thumb.jpg.e523dbad54ec44dbd470e9e179052775.jpg

And here is the video of the behavior:

 

What guys do think about it? Should I replace the pallet fork or am I missing something else during reassembly?

 

 

 

 

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20201025_153843.jpg

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Can you post some more pictures of this movement. Finishing seems downright horrible, escape wheel is stained, the visible portion of the hairspring is distorted. In fairness now is too late to return it, if your goal is simply to complete the watch I would get another mov.t from a reputable seller and not spend more good money after bad.

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Sure here some more; although I have reassemble the watch this afternoon. I don't have much.

Since I am learning, this is more of a study movement and I made some scratches in some places.

I can order a new nh35 for 25€, or order a palette fork + club wheel for 8 € (from ebay). So I am hesitating.

From your experience, what could cause this issue?

20201025_153512.jpg

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20201025_153544.jpg

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Hi! 

From your video, it appears as if the escape wheel tooth is not locking into the entry stone. The exit stone appears to lock appropriately. Several things to consider. 

  1. Broken or chipped entry pallet stone. 
  2. Loose entry pallet stone. 
  3. Malpositioned entry pallet stone (not making contact with the escape wheel teeth in the locking phase). 
  4. Entry lever/arm of the pallet fork is bent. 
  5. Too much endshake in the escape wheel (on the video it appears as if the escape wheel has a significant upwards vertical shift when spinning). 

I do have some other questions...

  • The movement seems significantly tarnished. Is this an original NH35, or a clone? 
  • Did this happen all of a sudden, or was the watch functioning properly beforehand? Did it happen before or after disassembly? 

In regards to your question about buying a new movement. I would recommend you do, especially considering that the NH35 is a relatively inexpensive movement. 

Best of luck! 

Guido

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Agree with guido, entery pallet fails to engage with escape teeth, perhaps has move outward in fork slot, can be adjusted.

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7 minutes ago, Nucejoe said:

Agree with guido, entery pallet fails to engage with escape teeth, perhaps has move outward in fork slot, can be adjusted.

Correction, jewel is to be moved outwards in fork slot. 

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4 hours ago, DrG said:

do have some other questions...

  • The movement seems significantly tarnished. Is this an original NH35, or a clone? 
  • Did this happen all of a sudden, or was the watch functioning properly beforehand? Did it happen before or after disassembly? 

Thank you all for your replies.

The movement comes from a Pagani Design submariner homage : PD-1661. I hope it is a genuine NH35a but really not sure about that. Here are some more pictures of the watch.

The watch stopped working (movement was stuck) after 1 day of wearing it. So I decided to dig into it instead of returning it with a 5% chance of being reimbursed...

During the disassembly, I was searching for the issue when suddenly all the power reserved get out of the mainspring with a high speed gear noise when checking the escape wheel. (the balanced wheel was removed, but not the pallet fork). I thought that I had found the issue so I decided to reassemble it and here I am.

I need to check but maybe, it is the bottom jewel of the escape wheel that moved and is making it too low for the entry pallet to block its movement. I will maybe disassemble the dial of the watch and the train wheels to inspect it again.

Thanks again for your tips

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1 hour ago, beastiole said:

During the disassembly, I was searching for the issue when suddenly all the power reserved get out of the mainspring with a high speed gear noise when checking the escape wheel. (the balanced wheel was removed, but not the pallet fork).

Was the pallet secured in place with the pallet bridge when the mainspring unwound suddenly or was the bridge removed or loose?  Since all the mainspring power was suddenly let down, you have to check for broken pivots in the escape wheel as well as in the pallet. 

1 hour ago, beastiole said:

I need to check but maybe, it is the bottom jewel of the escape wheel that moved and is making it too low for the entry pallet to block its movement.

If this is the case you will need a jeweling tool in order to get the lower escape wheel jewel back in place.

If the entry pallet jewel is out of place, it can be moved, but you will need to measure the appropriate distance from the escape wheel tooth in both the locking phase and impulse phase. This can be done "by eye" or with a dedicated measuring tool. You will also need to learn how to work Shellac in order to adjust that jewel. 🙂

Your enthusiasm for solving this problem is wonderful!! Even if you buy a new movement (which is my recommendation), keep working on this one until you find the problem. It's the best way to learn in watch repair and watch making. 

Regards, 

Guido

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Could you zoom in and get a higher magnification photo of the pallet fork?

In your second photo of the pallet fork, it appears that the pallet fork has a stress fracture where the arbor goes through the fork arms. Or is it a giant scratch from poor finishing. 

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10 hours ago, HectorLooi said:

Could you zoom in and get a higher magnification photo of the pallet fork?

In your second photo of the pallet fork, it appears that the pallet fork has a stress fracture where the arbor goes through the fork arms. Or is it a giant scratch from poor finishing. 

looks like reflection to me...

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Hi there,

(pictures are not really good and deformed as they are taken using a smartphone with a 8x numerical zoom)

After some investigations, I found what was the cause of the pallet fork not stopping the escapement wheel.

I initially ordered a pallet fork + escapement wheel (sold together) in the objective of replacing the pallet fork .

I compared them but they looked similar: (forged the visible fiber in the newer on the left)

20201103_215751.thumb.jpg.748f4097ae7ecf4bf82c8801c322a350.jpg

I them inspected the movement and tried understand where the problem should lie, and decided to record a video with my phone to see something as I didn't own a magnifier / microscope.

So I removed the escapement wheel and compared it with the new one that come with the pallet fork:

20201103_202645.thumb.jpg.e466f0c93bd84b7fba333b7b81696b4d.jpg

And, voilà. New one on  the left, old one on the right. You can easily spot the difference and understand why the wheel was jumping during the rotation...

I cleaned the fibers that you can see on the picture again, and installed the new one in the watch.

The movement was working again \o/ .... with not much amplitude so the watch was gaining 20sec/min.

I decided to rework the hairspring, after ordering a magnifier, and .... I damaged it ... with my tweezers ...

Fortunately, I managed to fix it and reassemble it. And now ... it works without problems \o/.

The movement still loose a min/day, but I will now try to regulate it.

Thank you.

 

 

 

 

 

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Good save on the hairspring. 

Wind it up and let it run a few (20) minutes before you begin your evaluation of it's timing.

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