Junghans 98 stops running dial up.

[Gaus]

Hello watchlovers,

 

I serviced a junghans 98 (1971, 7 jewels). As I started the mainspring was fully wound but the watch wasn't running. The balance moved freely. I disassembled the movement, cleaned al the parts, put it together and greased and oiled. After assembly the watch was running very nice (dial down) for about two days. The ampitude was about 260. The beaterror about 3.2. But, if I turn the movement, it stops running. I checked the jewels of the balance but I can't find faults. The wheels have no jewels. Is this a pivot problem?  

Edited January 15 by Gaus

[tomh207]

I would look at the beat error, it’s way too high. If the beat is way out it can cause a watch to not start or just stop.

 

Tom

[Klassiker]

When you say stops, you mean stops immediately? No time to get a reading on the timegrapher? If you give it a shake, will it start running dial up, or not? What happens if you turn the microphone back to dial down?

My first thought is that the hairspring is fouling somewhere, or the upper pivot of the balance staff is broken.

[Gaus]

Hello Tomh207, you're partly right, but then it wil be dial up and dial down I suppose.

[tomh207]

11 minutes ago, Gaus said:

Hello Tomh207, you're partly right, but then it wil be dial up and dial down I suppose.

I would still look at this first as A) it’s low hanging fruit B) with beat error like this I would think the inherent dynamic differences between DU & DD would possibly be asymmetrically affected.

 

Tom

[Neverenoughwatches]

4 hours ago, Gaus said:

Hello Tomh207, you're partly right, but then it wil be dial up and dial down I suppose.

You could test this again with just the balance to varify it is something balance assembly related and nothing else. Removing the pallet fork ( make sure the mainspring is unwound ) will isolate the balance for testing, turn the movement over to dial up position and give the balance some air from a puffer to set it in motion . You will see the oscillations from the side , they should last around one minute, or does the balance stop as before ?

[Gaus]

Thank you all for the responses, I'll investigate further and will let you know. 

[Gaus]

Hello guys, it took some time te work again on the watches. I promised to let you know what I found out. There was too much sideshake on the escapewheel (not jewelled). I found a donor plate and now it works fine.