ZIM (Pobeda) 2602 balance complete replacement

[JohnC]

Hi all, I have a newer (80s) ZIM 2602 that was my first fix-it project after taking Mark's course. It's been on hold for a month while I waited for a NOS mainspring and balance complete (pivots were bent).

I installed both of these last night, and the watch has developed a new problem. After installing, the watch ran strong for 2-3 minutes, and then suddenly stopped. Giving the balance a little push, the watch will start again, and sometimes reach what looks to be a good amplitude. Other times it will complete 1-2 weak vibrations, and stop again with the impulse jewel resting between the horns.

As I said, the mainspring is new. The train runs freely and easily with the pallets removed.

I have one suspicion - that the guard pin is too long and is hitting the safety roller.

My reason for this suspicion is that the balance complete I received appears to be for an older vintage of Pobeda, as it has timing screws. Comparing the rollers, I can see that they are not identical. On the NOS (but maybe older-vintage) balance, the safety roller is definitely chunkier than on the original balance.

I don't have the means or the knowledge to swap rollers, but my questions are whether a fouling guard pin could cause the symptoms I have described, and whether anyone has tried installing a NOS balance complete on a ZIM 2602, and whether they've encountered the same issues. Thanks very much for your help.

 

[Nucejoe]

Did you release all power reserve to observe impulse pin in the fork horn?

Mark the third wheel with ink, to observe if there is a pattern in the stoppage.

Perhaps tiny hair rubbing on escape wheel or balabce rim.

Bad escape teeth or pinion.

[JohnC]

Thanks - yes, I let the power down and I can see the impulse jewel between the horns.

I'll try the other steps and let you know the result. The NOS balance was packaged in some cotton wool so it's possible there is a hair stuck on there.

[JohnC]

@Nucejoe you were right, the escape wheel was actually reversing slightly when one tooth hit the pallet exit stone. This caused the watch to gradually lose amplitude until it stopped.

Cleaning the escape wheel has helped the problem a bit, and the watch no longer stops. However, amplitude is still poor (about 170) and I can sometimes see the balance wheel stutter (again, because one of the teeth or a pinion leaf on the escape wheel is bad - I'm not sure which, as I can't see a problem visually).

Do you think this is a cleaning problem or damaged-wheel problem? I have cleaned the wheel several times now (although I do all my cleaning by hand). I have some scrap 2602s coming in the mail, so I may just try switching out the wheel.

[Nucejoe]

Sound like a damaged escape tooth,  just to make sure the issue is not dirt, I put some naphta on all escape teeth while movement is running, it will gains considerable amplitude which often makes it keep running and somewhat cleans itself. 

To apply the naphta, I use a small screwdriver as oiler. 

Good luck.

[anilv]

Is the watch in beat?

Anilv

[JohnR725]

I have a couple links below for your watch because I always like to see what were dealing with. The rules are watch repair is not universal in that things change with time and this appears to be a Russian watch or perhaps a Soviet Union watch? The reason this becomes interesting is the early Soviet watches and possibly all of them even though that made in a factory there made more like something much older where the parts almost have to be fit. So the ability to just get a balance complete and drop it in without consequences is going to be More challenging perhaps

In one of the problems we have with a nonfunctional watch is we don't know what the condition of the watch is before you started doing repairs. So if you repair what you perceive was the issue conceivably there may be other issues.

17 hours ago, JohnC said:

My reason for this suspicion is that the balance complete I received appears to be for an older vintage of Pobeda, as it has timing screws. Comparing the rollers, I can see that they are not identical. On the NOS (but maybe older-vintage) balance, the safety roller is definitely chunkier than on the original balance.

The problem with Russian watches is they tended to have manufacturing variations. Then you appear to have an entirely perhaps different balance wheel. Roller conceivably could be thicker but it's diameter definitely has to match the old one. The pivots have to match for diameter and length of the staff becomes important. Often times something that I was frown on is shimming under the balance bridge is often seen on Russian watches. So you do need to look at very very carefully the new versus the old as that alone could be our problems. In addition to of course whatever else may or may not have existed.

2 hours ago, JohnC said:

Do you think this is a cleaning problem or damaged-wheel problem? I have cleaned the wheel several times now (although I do all my cleaning by hand). I have some scrap 2602s coming in the mail, so I may just try switching out the wheel.

 

2 hours ago, JohnC said:

Cleaning the escape wheel has helped the problem a bit, and the watch no longer stops. However, amplitude is still poor (about 170) and I can sometimes see the balance wheel stutter (again, because one of the teeth or a pinion leaf on the escape wheel is bad -

It be much much better verify exactly what the problem is before you start swapping parts. If one of those watches that comes in the mail is in beautiful running condition then maybe keep fat. But swapping components from other watches that may or may not have their own problems makes things much more challenging for finding issues.

How did you lubricate the escapement?

 

https://17jewels.info/movements/z/zim/zim-2602/

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&ZIM_2602

[JohnC]

Thanks for your responses. 

Anilv, the watch is maybe not perfectly in beat, but close enough that it shouldn’t be stopping (3.5 ms). 

John, I used Moebius 9415. No sign of a shim.

I did not express myself clearly before. What I meant to say is, the roller is actually larger diameter on the NOS balance. That’s why I was concerned about the guard pin. 

The watch had a definite low amplitude problem when I started, but I attributed this to the bent pivot. 

John, your point is well taken. I am just going to get my hands on the definitely correct balance, then start troubleshooting again (we’ll see if any of these scrappers has a good one). Thank goodness I have several projects to tinker with, as the post is extremely slow right now. Anyway, I’ll post on this one again in another couple weeks. 

[anilv]

Yes, 3.5ms with a new ms would be ok.

Another thing I just thought of is that most of these Russian watches have an overcoil hairspring. If the curve is not correct the outer coil may touch the next one as it goes up and over. 

Anilv

[JohnR725]

4 hours ago, JohnC said:

I did not express myself clearly before. What I meant to say is, the roller is actually larger diameter on the NOS balance. That’s why I was concerned about the guard pin. 

If the roller table is physically larger then you definitely going to have an issue. Usually this stuff is adjusted reasonably close and it's physically too big year probably rubbing which would be undesirable.

[JohnC]

Hairspring looks good, but I think John is right and I need to just get a balance of the correct vintage.

[JohnR725]

I'm attaching an image you might find it helpful.

You will note there is a procedure here first you check the Horn clearance. Most people don't because this is controlled by the banking pins which are typically hopefully Where there supposed to be. If you're dealing with American pocket watches like I typically do they are movable so I have to check this every single time I work on a watch. Once you verify this is correct you do not move the banking pins to fix other issues only for this clearance.

Then you would now check your guard pin clearance. But if you put a balance wheel and that's not correct the safety rollers physically too large then you conceivably will have zero clearance. Depending upon the pallet fork and how the guard pin is mounted it sometimes can be adjusted.  but it really would be best if you got the right balance Wheel.