Seiko NH35 Problem - opinions please!

[FudgyDocker 3,501]

Hi all,

I have a gen with an NH35 movement, but the auto-wind doesn't seem to work, Hand wind is no problem. I don't have another watch with a similar movement, so I can't compare. Looking for an expert-ish opinion on what may be wrong, The rotor moves gear 'A' absolutely fine, but I'm pretty sure that gear 'B' should also move, although it looks to me as if there are hardly any teeth on it. Can anyone confirm or deny my suspicions, please? I know @NCRich has seen quite a few of these, but advice from anyone who knows would be welcome.

Thanks in Advance

[NCRich 13,751]

Take the rotor off. 

[GenTLe 1,509]

Below gear A there is an eccentric. The eccentric moves the 2 levers that are on the gears of the gear B, so the gear B doesn't rotate as it was connected to another gear, but is instead pushed and pulled from the 2 levers that you can see on it:

 

 

[FudgyDocker 3,501]

@NCRich @GenTLe - I removed the rotor and the cover plate. Jesus, those screws are the smallest I've seen!!

[Aramis2288 6,254]

@FudgyDocker, I suppose that since you are asking for technical advice you may be more interested in fixing your movement rather than swapping it, but just FYI, NH-35 / NH-36 replacement costs about 40 quids from the UK based Seiko Mods shop and about 20 quids from AliExpress. So in case if you won't succeed fixing the issue, swapping the movement is very cheap and straightforward. 

Edited August 20, 2021 by Aramis2288

[FudgyDocker 3,501]

4 minutes ago, Aramis2288 said:

swapping the movement is very cheap and straightforward.

Yeah, a brand new movement is £29 +VAT from Cousins, but "simple and straightforward" comes into question when you have a habit of completely fucking up every second hand that you have ever tried to re-seat.

[GenTLe 1,509]

3 hours ago, FudgyDocker said:

@NCRich @GenTLe - I removed the rotor and the cover plate. Jesus, those screws are the smallest I've seen!!

 

Lol, if those are small, don't EVER try to work on a Miyota 9015  

By the way, try to rotate the gear with a hole, check if the levers move and make the "gear with small teeth" to move and male move also the gear over the mainspring barrel (top left under the big screw),  but first I'd put the plate back as the "gear with small teeth" now doesn't have any support for the upper pinion...

[FudgyDocker 3,501]

1 hour ago, GenTLe said:

try to rotate the gear with a hole

Have replaced the plate and rotating gear A makes the ellipse move the levers back and forth, but both the gear with small teeth and the mainspring gear just rock back and forth. It does do what I'd call 'wind' the mainspring at all.

 

[GenTLe 1,509]

6 hours ago, FudgyDocker said:

Have replaced the plate and rotating gear A makes the ellipse move the levers back and forth, but both the gear with small teeth and the mainspring gear just rock back and forth. It does do what I'd call 'wind' the mainspring at all.

 

So check if the teeth at the end of the "magic leavers" are really against the teeth of the gear B and not below or over it. If they are in the correct position and it behaves that way it probably means that either you need a new "magic leavers" or a new B gear (most probable the lever).

They should work this way:

 

 

[FudgyDocker 3,501]

36 minutes ago, GenTLe said:

So check if the teeth at the end of the "magic leavers

I think that the 'magic levers' are not so magic right now.

The 'push' side of the lever is OK and if you move it away gently with tweezers it springs back to position. If you do the same with the 'pull' side of the lever it doesn't spring back and stays out. So I'm guessing that is screwed,

Now then, how to get a replacement, and how difficult is it to change?

[NCRich 13,751]

18 minutes ago, FudgyDocker said:

I think that the 'magic levers' are not so magic right now.

The 'push' side of the lever is OK and if you move it away gently with tweezers it springs back to position. If you do the same with the 'pull' side of the lever it doesn't spring back and stays out. So I'm guessing that is screwed,

Now then, how to get a replacement, and how difficult is it to change?

Buy a movement.  Its a 15 minute job.

[FudgyDocker 3,501]

7 hours ago, NCRich said:

Buy a movement.  Its a 15 minute job.

 

19 hours ago, FudgyDocker said:

Yeah, a brand new movement is £32 +VAT from Cousins, but "simple and straightforward" comes into question when you have a habit of completely fucking up every second hand that you have ever tried to re-seat.

Yeah, unfortunately, I already made a comment on that. Bit galling, when you only just got the watch a couple of weeks ago.

[NCRich 13,751]

55 minutes ago, FudgyDocker said:

 

Yeah, unfortunately, I already made a comment on that. Bit galling, when you only just got the watch a couple of weeks ago.

What is it?

[FudgyDocker 3,501]

I've found the part on Cousins, but it's on back order so I'll wait for it to come in, and then replace it.  Looking at the service video, there isn't too much to disassemble to do it.

[GenTLe 1,509]

@FudgyDocker Check this out: https://www.seikoserviceusa.com/uploads/datasheets/4R35B_4R36A.pdf 

The part 0831 183 is out of stock on  CousinsUK but there is this one on eBay (but too expensive if you ask me, on cousing it's 4£): https://www.ebay.co.uk/itm/184870160196

You can anyway get this: https://www.aliexpress.com/item/4000437713038.html and this: https://www.aliexpress.com/item/4000437635794.html and have the complete bits to fix the whole thing (they are also from the same shop, so you cut the shipping costs) without haveing to mess with movement replacement and possible damages to dial an hands 

 

[FudgyDocker 3,501]

@GenTLe - I don't know why I'm so cack-handed at doing second hands, but I just can't seem to seat them with snapping a drive pinion off.

Maybe buy a few more £8 sand-filled 2813 movements as guinea pigs, and keep trying

 

[GenTLe 1,509]

1 hour ago, FudgyDocker said:

@GenTLe - I don't know why I'm so cack-handed at doing second hands, but I just can't seem to seat them with snapping a drive pinion off.

Probably you just push them too much (it doesn't need so much pressure) and not in straight vertical push. Only delicate one is the chrono central sec of 7750s as they need quite some pressure not to slip when resetting, and also a movement holder that has the pinion support from below (like this: https://www.aliexpress.com/item/1005002781949705.html)

I found this to be good for that job of setting hands: https://www.aliexpress.com/item/32974767120.html eventually pass a bit of grip 600 sand paper (keeping the thing vertical) on the plastic edges of the pushers to smoot them out. But to use this you also need movement holders like these: https://www.aliexpress.com/item/1005001423832027.html to properly keep the movement in position.

 

[BoobBandit 1,311]

On 20/08/2021 at 18:20, GenTLe said:

So check if the teeth at the end of the "magic leavers" are really against the teeth of the gear B and not below or over it. If they are in the correct position and it behaves that way it probably means that either you need a new "magic leavers" or a new B gear (most probable the lever).

They should work this way:

 

 

That is a cool little graphic! thanks!