Junghans "Synchron" Wall Clock - UK Vintage Radio Repair and Restoration Discussion Forum

PsychMan · 25th Jul 2016, 9:56 am

I bought a clock believed to be 30s-40s of German manufacture. Its a synchronous wall clock. I wired it up yesterday and got it running, the movement runs very quietly and it kept perfect time for at least 4 hours.

I decided to leave it running overnight and this morning found it had started running backwards during the night. As far as I can see no power cuts last night so a bit baffled by this? I've started it in the correct direction again and am keeping an eye on it.

The starter lever did feel loose and initially it was hard to see which way to move it to start the clock. Its possible this lever was left in the incorrect position when I started it. Not too sure however if this makes an difference.

I do plan on cleaning and lubricating the movement, but have not done so yet.

PsychMan · 25th Jul 2016, 5:44 pm

Yes once again found the clock is running backwards after some time. I'm going to need to get to the mechanism.

Any idea what could cause it to do this? I've had no power interruptions

25th Jul 2016, 8:24 pm

If it is a bit stiff (dry oil etc.) any small variation of the mains could cause it to go backwards. Simply switching on something could make the mains waveform bad enough.

PsychMan · 26th Jul 2016, 12:51 pm

Looks like ill have to bite the bullet and clean the movement. Ive not done anything with clocks before so hope it wont be too difficult. Hopefully I can clean and oil enough of it in situ without tearing it apart. Ill add some pictures tonight

PsychMan · 27th Jul 2016, 11:26 am

Ive attached some pics of the clock and movement. I found the starter wasn't setup very well and often got stuck, this has been rectified on reassembly and works better.

I oiled any pivot points I could reach, but when it came to the rotor bearings, I think these are what you call "sintered"?

I didn't have a light enough oil for this so will have to go back to this when I get some sewing machine oil. The mech seems to run a bit smoother, but I think the thicker oil is making the rotor move less freely.

One other possibility that occurred to me, is whether the mains flex behind the clock was moving and coming into contact with the starter, and causing these problems. If its that I'll feel very stupid indeed!

All the same it will be nice to oil those motor bearings and look at earthing this somewhere for safety.

PsychMan · 27th Jul 2016, 11:27 am

This pic wouldn't fit in the last post. But I believe the brass stuff is under the black clip

25th Jul 2016, 9:56 am	#1
PsychMan Octode Join Date: Jun 2013 Location: Fleet, Hampshire, UK Posts: 1,764	Junghans "Synchron" Wall Clock I bought a clock believed to be 30s-40s of German manufacture. Its a synchronous wall clock. I wired it up yesterday and got it running, the movement runs very quietly and it kept perfect time for at least 4 hours. I decided to leave it running overnight and this morning found it had started running backwards during the night. As far as I can see no power cuts last night so a bit baffled by this? I've started it in the correct direction again and am keeping an eye on it. The starter lever did feel loose and initially it was hard to see which way to move it to start the clock. Its possible this lever was left in the incorrect position when I started it. Not too sure however if this makes an difference. I do plan on cleaning and lubricating the movement, but have not done so yet.

25th Jul 2016, 5:44 pm	#2
PsychMan Octode Join Date: Jun 2013 Location: Fleet, Hampshire, UK Posts: 1,764	Re: Junghans "Synchron" Wall Clock Yes once again found the clock is running backwards after some time. I'm going to need to get to the mechanism. Any idea what could cause it to do this? I've had no power interruptions

25th Jul 2016, 8:24 pm	#3
Guest Guest Posts: n/a	Re: Junghans "Synchron" Wall Clock If it is a bit stiff (dry oil etc.) any small variation of the mains could cause it to go backwards. Simply switching on something could make the mains waveform bad enough.

26th Jul 2016, 12:51 pm	#4
PsychMan Octode Join Date: Jun 2013 Location: Fleet, Hampshire, UK Posts: 1,764	Re: Junghans "Synchron" Wall Clock Looks like ill have to bite the bullet and clean the movement. Ive not done anything with clocks before so hope it wont be too difficult. Hopefully I can clean and oil enough of it in situ without tearing it apart. Ill add some pictures tonight

27th Jul 2016, 11:26 am	#5
PsychMan Octode Join Date: Jun 2013 Location: Fleet, Hampshire, UK Posts: 1,764	Re: Junghans "Synchron" Wall Clock Ive attached some pics of the clock and movement. I found the starter wasn't setup very well and often got stuck, this has been rectified on reassembly and works better. I oiled any pivot points I could reach, but when it came to the rotor bearings, I think these are what you call "sintered"? I didn't have a light enough oil for this so will have to go back to this when I get some sewing machine oil. The mech seems to run a bit smoother, but I think the thicker oil is making the rotor move less freely. One other possibility that occurred to me, is whether the mains flex behind the clock was moving and coming into contact with the starter, and causing these problems. If its that I'll feel very stupid indeed! All the same it will be nice to oil those motor bearings and look at earthing this somewhere for safety. Attached Thumbnails

27th Jul 2016, 11:27 am	#6
PsychMan Octode Join Date: Jun 2013 Location: Fleet, Hampshire, UK Posts: 1,764	Re: Junghans "Synchron" Wall Clock This pic wouldn't fit in the last post. But I believe the brass stuff is under the black clip Attached Thumbnails