Siemens MU 1600 Repair Suggestions
 

Hey everyone, I'm new here, joined to try and find out about this Cyclometer clock. I managed to pick it up from a boot sale. It's not working unfortunately but I thought I might be able to tinker with it.

I've taken it out of its case and it all seems intact. Except for a little night light bulb which seems to be missing. Looks like someone has already been nosing around inside it.. Interestingly, I did try and power it on outside of the case and I get no sign of anything. However when I put it back inside the case and power on I can hear a faint hum.. I wonder why that would be? Could the timepiece not working be as simple as the nightlight missing? I.e. it not creating a circuit somewhere?

Anyway, I've taken loads of photos of the inside but won't clutter up things here if I don't get any responses. If anyone knows a little about these thing I'd be really happy to hear about possible reasons for faults and I'll happily post up all the mechanism photos. Either that or suggestions for alternate avenues to find further information? Any help much appreciated.

Re: Siemens MU 1600 Repair Suggestions
 

The hum you can hear probably is the motor. The type of motor used in these clocks can usually sit in a stalled state indefinitely. I would be looking for a mechanical fault: either something is fouling, or something is turning freely and not transferring drive to the next wheel.

Re: Siemens MU 1600 Repair Suggestions
 

It's run by a synchronous motor, it has very little torque so anything jamming it, or excess friction can stall it. See if you can rotate the rotor by hand, and yes, we would like to see pictures of the mechanism. Use the "Manage attachments" button below the typing window.

Re: Siemens MU 1600 Repair Suggestions
 

Hey there @julie_m @rambo1152 thanks for the replies.

I can't see anything which would be jamming the motor. The rollers turn easily too when I set the time. Looking around the net, I wonder if the motor needs some oil?

I've attached the photos. There's a higher resolution version here:
********************a/BtjdQ

The motor looks quite a tight fit so I'm unsure how easy it would be to get at it. I'll open the case up again today and check it out. Any more suggestions after seeing the internals?

Re: Siemens MU 1600 Repair Suggestions
 

Looks like there's a yellow gear wheel fitted to the motor shaft?

Can you free the motor by rotating this gear?

Is there a voltage rating on the motor? I can see a transformer which may supply the motor with a low volatge, or it could be something to do with the alarm function.

Re: Siemens MU 1600 Repair Suggestions
 

Hi Station X. Yep the yellow gear is attached to the motor shaft. I've given it a few turns but no joy. The motor is still just whirring quietly but with no actual movement taking place.

There does appear to be a voltage rating on the motor but unfortunately it's obscured with only the 0v at the end being visible. The manufacturer is visible though, Kundo?

I'd need to take the whole frame apart to be able to be able to get at the motor and see it's voltage.

I guess my options are currently to apply some oil and see if that works? If that doesn't, then I would assume taking the frame apart and separating the motor. Could the motor be cleaned? I've seen people using isopropyl?

Re: Siemens MU 1600 Repair Suggestions
 

If the motor is making a sound, that means that power must be getting to it.

Either the motor is faulty or it's so stiff that it cannot rotate. If the latter, then lubricating the motor's bearings with say clock oil may cure it.

Any chance you could measure the voltage on the wires going to the motor? I assume they terminate on the Printed Circuit Board (PCB) somewhere?

Is there anything else on the PCB apart from the transformer and two resistors?

EDIT. I've just had a closer look, and the yellow gear isn't actually on the motor shaft. It appears that the white gear is mounted on the motor shaft and drives the yellow gear. Is it possible that the motor shaft is in fact rotating, but the white gear is slipping on the shaft due to say a cracked hub?

You'll have to work out the gearing arrangement. The fast running motor will be geared down so that the units half of the minutes display rotates once every 10 minutes. That means that small gears will be driving large ones.

Re: Siemens MU 1600 Repair Suggestions
 

It's working! :)

I gave the drive shaft a turn while power was applied and it started turning on its on. Brilliant, what a great feeling! I'm leaving it running and it's been keeping good time the past few hours. The alarm works fine too!

I'm wondering whether I should give it a little maintenance now or leave it be? Perhaps still put some clock oil on the drive shaft? Or how about some on the nylon cogs too or grease?

The night light bulb still needs replacing. I've ordered this one

https://www.ebay.co.uk/itm/Neon-Bulb...72.m2749.l2649

I'm sure it'll need a resistor but I'm not too sure what type. I'm a complete beginner at this, but I'm very much interested in learning. I've a multimeter on the way, would I be able to use that to discern what v the motor uses? I presume that's what the ebay description means by, "Suitable external series resistor for 110V is 33K and for 240V is 100K ¼W" Or would it mean the mains itself? In which case it would be 230v?

Any help much appreciated!

Re: Siemens MU 1600 Repair Suggestions
 

I think it would be unusual for a neon lamp to be used here.

What does the lamp holder look like.

When you get a meter, check what voltage is present at the lamp holder.

As for lubrication, a spot of clock oil applied to the motor shaft close to the case is probably in order. Clock experts on here can no doubt advise.

Re: Siemens MU 1600 Repair Suggestions
 

It should respond to the same treatment as a record player motor and the gears even run dry like the idler on the rim of the turntable.
The gear closest to the motor is a different colour indicating that it is made of oil proof plastic due to it being close to the bearing in the end of the motor.
Nylon gears fall to bits if you put WD40 on them.

Re: Siemens MU 1600 Repair Suggestions
 

I would use a 220k ohm resistor in series.

Re: Siemens MU 1600 Repair Suggestions
 

Thanks for the replies everyone.

I've been keeping the clock going all daytime and it's only stopped once, when it was clicking over the big hour cylinder. Since then it's run fine tho. However, when I turned it on this morning it did require another little 'nudge' to get working again. I wonder if that indicates that I should definitely use a little clock oil on the shaft?

@Station X Going by this video and the look of the missing light's lower portion, I'm pretty sure it's a neon light. The 2 photos show the missing (broken off by previous owner?) bulb and where it connects to the circuit board. Joints 16 and 17.

https://www.youtube.com/watch?v=iJetgnsNDQw

My meter has arrived and I'm reading up on how to use them now. How would I test the voltage of the lamp holder? I can't see much where the old bulb has been broken off. Could I place the meter probes on solder joints 16 and 17?

@Refugee That's interesting about the different coloured wheel, thanks!

rambo1152 I bought the follow (100k version) ohm resistor as per the bulbs instructions? Would that not be appropriate?
http://www.ebay.co.uk/itm/100-Pack-C...CpFJ1FXW7AyBFQ

Thanks again for the help everyone.

Re: Siemens MU 1600 Repair Suggestions
 

If the lamp is/was a neon, the resistor for it may be on the PCB already. Try tracing the PCB tracks from points 16 and 17.

Re: Siemens MU 1600 Repair Suggestions
 

Ahh good point. I can't see any resistor on the board though. I'm hoping it'll be inside that blue tubing.

I'm thinking of desoldering joints 16 and 17 with an iron and solder sucker. That way I can check the tubing more easily and re attach later. That should do any harm should it?

Re: Siemens MU 1600 Repair Suggestions
 

I would just recover a neon from an old kettle. They come with the plastic tube and resistor already attached.
I find that the neon can be got to by treading on the old kettle to crack the plastic away.
Shovel and broom not included.

Re: Siemens MU 1600 Repair Suggestions
 

In my opinion the solder sucker is unnecessary. Just pull the wire from the other side as you heat each joint.

Use 60/40 tin/lead solder, none of that lead free junk.

Re: Siemens MU 1600 Repair Suggestions
 

Unnecessary maybe, but if used carefully it will make the job easier, at least when it comes to replacement time when a nice clear hole is good.

Re: Siemens MU 1600 Repair Suggestions
 

Thanks again for the replies everyone. I detached the bulb tubing and.. I think the resistor has seen better days! I've already received the new bulbs and resistors so I just need to get hold of some shrink tubing before attempting the rebuild.

The clock itself is still running fine. I keep it going during the day but turn it off overnight. Unfortunately, it still needs a little nudge to start when turned on in the morning from cold. I'm wondering if this indicates the need to add a little clock oil to the motor shaft? What do you guys think? Obviously I'd rather the motor just work if turned on from being off, rather than have to open it up each time.

Re: Siemens MU 1600 Repair Suggestions
 

That's a 150k resistor.

Re: Siemens MU 1600 Repair Suggestions
 

Ahh, thanks for that @Station X. Would that mean that the 100k ones I've got aren't suitable? Even though the bulb's eBay page states a 100k one? I've also just noticed @rambo1152 's post recommending a 220k instead. What would the theory be behind that, providing a dimmer light?