What the heck is this - Hamazawa 5023A

[GuyMontag]

Over the last couple of months I've been working on watches that all have the same movement and am getting bored so I went to my "To be serviced" pile and found one that looked interesting. A LeGant 17 Jewel diver. Opening it up I kinda just stared at the movement for a minute, not really sure what to make of it. Where is the balance bridge? Why is the hairspring stud fixed to the mainplate? How can the pallet interact with the impulse jewel when it is pointing away from it?

I wanted something different but not necessarily something that will be too challenging and have me pulling my hair out. Does anyone have any experience with this movement (or a tech sheet)? I'm just wondering how straight forward (or not) it will be to service (it runs when wound).

 

 

 

Edited February 27, 2023 by GuyMontag

[KarlvonKoln]

 

Well...um...at least it isn't Chinese. 

Edited February 27, 2023 by KarlvonKoln

[JohnR725]

2 hours ago, GuyMontag said:

Where is the balance bridge? Why is the hairspring stud fixed to the mainplate?

think of this as it easier to disassemble watch because the balance bridge has been  consolidated with another bridge one less bridge to remove is always a good thing. it almost looks like it's missing is pallet fork bridge that's even less things to deal with for disassembly. Except all will be lost for reassembly

googling revealed this is probably more but this is as far as I was going to go I was hoping for more inside pictures the movement maybe you will bill it takes some for us?

https://www.watchuseek.com/threads/hamazawa-movement-what-is-this-thing.5068197/

before I closed out my search I discovered another interesting discussion shame I can't read the language but I can see the pictures pallet fork is quite interesting which is what I was curious about at least it has jewels.

https://www.mobile01.com/topicdetail.php?f=376&t=5964735

then did confirm what I suspected you don't have to worry about the pallet fork bridge it's been consolidated with the rest of everything on the one bridge. But he does have nice step-by-step pictures. Didn't try but I assume Google translate probably translate for you.

 

Edited February 27, 2023 by JohnR725

[lexacat]

Google translated from that link

This machine was mentioned earlier The design of the core is simply a nightmare for maintenance personnel. The entire movement has only one bridge plate!!

Seems promising!

[oldhippy]

This is the type of movement you will get when you buy a cheep watch, or you get ripped off. It's the sort of thing that are sold on market stalls. My opinion on watch movements that are not worth repairing would be chuck it out.  

[spectre6000]

Interesting movement for sure. Looks like a fun time! Hope the plastic parts are in good condition, as I imagine it won't be easy to find spares.

[rossjackson01]

Information

https://17jewels.info/movements/h/hamazawa/hamazawa-5026b/

https://chronopedia.club/Hamazawa

 

[JohnFrum]

Aligning six pivots to the top bridge must be a joy. Interesting movement though. 

[GuyMontag]

10 hours ago, JohnR725 said:

think of this as it easier to disassemble watch because the balance bridge has been  consolidated with another bridge one less bridge to remove is always a good thing. it almost looks like it's missing is pallet fork bridge that's even less things to deal with for disassembly. Except all will be lost for reassembly

googling revealed this is probably more but this is as far as I was going to go I was hoping for more inside pictures the movement maybe you will bill it takes some for us?

https://www.watchuseek.com/threads/hamazawa-movement-what-is-this-thing.5068197/

before I closed out my search I discovered another interesting discussion shame I can't read the language but I can see the pictures pallet fork is quite interesting which is what I was curious about at least it has jewels.

https://www.mobile01.com/topicdetail.php?f=376&t=5964735

then did confirm what I suspected you don't have to worry about the pallet fork bridge it's been consolidated with the rest of everything on the one bridge. But he does have nice step-by-step pictures. Didn't try but I assume Google translate probably translate for you.

 

Thanks, the pictures in that last link help. The pallet fork looks like it mutated and grew a third arm...

 

9 hours ago, lexacat said:

Google translated from that link

This machine was mentioned earlier The design of the core is simply a nightmare for maintenance personnel. The entire movement has only one bridge plate!!

Seems promising!

Good times!

 

I'll at least disassemble and see what's up. Could be fun. Probably not.

BTW, what is the recommended cleaning procedure for the plastic parts? I assume just some warm soapy water? Also, theses parts are not oiled are they?

[GuyMontag]

Only 7 total screws, and one of those just holds on a non-functional plate with the Hamazawa name on it. The barrel was odd. The arbor just pushes out and the mainspring hooks on to a hook on the lid of the barrel. I tested a mainspring winder before cleaning as the coil on the spring looked very tight. I was able to (barely) force a size 5 arbor through the central coil with a size 6 barrel.

 

[GuyMontag]

Ugh. This one is quite frustrating. Because the entire train, from the mainspring to the balance wheel has a single bridge, you can't test the free running of the train by giving the barrel a bit of a nudge before installing the pallet fork. And it's not running. I've checked every pivot and they are all in their jewels, top and bottom,  and every wheel is meshed with the next in line pinion. The mainspring is holding power when wound. The impulse jewel is centered between the pallet stones. So I'm not really sure where the issue lies. It was running before I stripped it down so if I have everything assembled correctly it should run. I just can't figure out where I am going wrong.

Installing the train bridge actually isn't that bad, I've done it twice now and it doesn't take more than a minute or two. So I think maybe my next step should be (?) to start removing the train one-by-one starting with the balance, replace the bridge, and work my way back? Any thoughts on this?

 

[Waggy]

Did you check for play in the barrel arbor and main plate, I had a watch a while ago which was binding up because there was too much play - something you can check out quickly without having to totally assemble or strip (I assume).

Also can you tell if power is getting to the pallet fork, does it want to flick back and forth, this will give you an indication if power is getting through the train of wheels and you can concentrate on the balance as the most likely culprit

Let us know how you get on.

[GuyMontag]

Its hard to check the barrel endshake as the arbor can slide freely up and down within the barrel (which means the barrel can slide up and down the arbor). It's a really weird design. I have a video so will see if I can't upload it to youtube in the morning.

The issue with checking power delivery to the pallet fork is that the balance isn't meant to be removed for servicing; it's fixed to the mainplate via the balance stud. I can remove it (and will if I can't first track down the issue), I would just have to remove the balance stud from the mainplate.

Now that I'm thinking about it, I haven't yet installed the train side balance cap jewel (the dial side is in) , and I wonder if maybe that is affecting the height of the impulse jewel in relation to the pallet fork. The impulse jewel is on the topside of the balance instead of the bottom. It's such an odd movement.  I'll give that a shot in the morning.

Edited March 3, 2023 by GuyMontag

[Waggy]

Wow, sounds like a real oddball you have there, will be a great achievement if you can get it going!

[HectorLooi]

Would it be possible to leave out the pallet fork first and test the train for smoothness?

The pallet fork can be inserted later by loosening the screws of the plates on the escapement end.

[spectre6000]

My exact thought. Beat me to it.

[GuyMontag]

11 hours ago, HectorLooi said:

Would it be possible to leave out the pallet fork first and test the train for smoothness?

The pallet fork can be inserted later by loosening the screws of the plates on the escapement end.

That sounds like a good plan, I'll give that a shot.

[GuyMontag]

 

 

The issue was the mainspring slipped off the hook on the barrel lid. When I originally used the mainspring winder I really had to force the arbor through the small size of the internal mainspring coil. When I removed the arbor I saw that the spring had somehow slipped off of the arbor and was lying against the arbor, crushing it. I bent it back to shape but I think what happened is that the shape wasn't ideal and the spring would slip off of the hook when it reached a certain tension. I bent it to a more ideal shape it at looks like it is holding a full wind.

 

Onward to the dial side.

[GuyMontag]

I got everything sorted except for one issue, and I haven't decided if I will even address it or just leave it and put the watch back in the drawer. The issue is that it is extremely difficult, to the point of really being non-functional, to put the watch into time setting position. There is no setting lever spring in this watch but rather there are bumps and grooves on the stem as shown below (pre-cleaning):

 

 

 

The bump to go from the quick set date to time setting is larger than from winding to quick set date and the setting lever that engages with the stem can't get over that larger bump. I noticed this before I cased the watch and added a bit more grease to that area and that seemed to sort it. But after casing it I am having the same original issue with not being able to negotiate that 2nd bump without using so much force that I'm sure it will break the setting lever after doing it a few times. I've tried loosening the setting lever a hair but I have to loosen it to the point where the stem just wants to come out of the movement. I'm sure there must be a reason why that 2nd bump needs to be bigger than the 1st but I can't think of it.

 

 

Edited March 4, 2023 by GuyMontag

[Klassiker]

Try greasing all the bearing surfaces of the stem to make sure sliding friction under load is minimised. I could imagine this solution being very sensitive to lubrication and susceptible to wear.

[GuyMontag]

13 hours ago, Klassiker said:

Try greasing all the bearing surfaces of the stem to make sure sliding friction under load is minimised. I could imagine this solution being very sensitive to lubrication and susceptible to wear.

That did the trick. I put quite a bit of grease pretty much everywhere on the stem and now it goes into the setting position quite easily.

[SFCamry]

Hi all - found this site searching for info on the Hamazawa 5023A.  I am a member on WUS and a moderator on Toyotanation (same user name on all).  I have been picking up the watch bug and am about to start servicing a pile.

Anyway, I have two of these movements, both Benrus.  The first one came in a lot of 22 watches I won (unit cost a little over $7 a watch) and it is running 0 to +3 s/d with a beat error of 0.1  Nice performance!  I saw another Benrus with the same movement on eBay so bought it so I would have spare parts/case/crystal (and honestly want to see if I can fit some of my other Benrus movements in the case).  The second one I received (a bit over $60) is not as great, ranging +84 to +104 or so with a 1.something beat error.  Serviceable I was thinking.  Then read above and think I may be in for a ride here. 

At some point I will take on the less performing one and see if I can get it running better, then using that as my learning curve service the well performing one (it does not appear to have been serviced in any close era of time: I polished the crystal up to make it as clean as it is).  Some great info above: I think I will just hand wind it back into the barrel after reading how the spring attaches.  Hoping to get them clean and lubed, slap on a nice strap, then sell as they are a tad small for my preference, even given the great performance of one of them.

 

 

 

Edited April 13, 2023 by SFCamry

[GuyMontag]

I'm surprised Benrus used these movements. Couple of good looking watches. Good luck!

These were my post-service notes I made:

1. It might be best just to hand wind the mainspring as the diameter of the inner coil on the mainspring is so small you have to really force a size 5 arbor (size 6 barrel) which in my case when I tried to remove the arbor after winding into the barrel, something happened and it ended up squashing the inner coil which made it difficult to get the lid (with the hook) back onto the barrel

2. You have to apply a LOT of grease to the winding stem where the setting lever sits. There are two position, the first is to quickset the date/day and the second is to set the time. It won’t be able to get over that second “hump” to get into the setting position unless there is a LOT of grease.

3. On the dial side the date jumper/spring needs to be tucked under the main body of the guard mechanism or it won’t work correctly.

Edited April 13, 2023 by GuyMontag

[SFCamry]

Thanks, good info.  I am lucky in that the date position is working fine on my stems, but I will grease them well.  How in the heck do you attach the mainspring to the underside of the barrel cover?  I have been thinking about that and trying to figure how that is going to work. 

[GuyMontag]

It didn't really require anything more than just putting the spring in the barrel and then putting the cover back on. I did pay attention to where the hole on the spring was in relation to where the hook was on the cover was before placing the cover back on. Then I just tested by turning the top of the barrel to make sure it engaged the spring.