Need help quieting noisy Sankyo electric clock

[Mark286]

Hello all. I just aquired a like new looking Sankyo 401 electric alarm clock. My only problem with it is that it has an audible grinding hum coming out of it. Not too loud, but loud enough for me to hear across the room. I’m pretty sure this sound is coming from the motor and not the other parts of the mechanism, but I could be mistaken. My question is, is it possible to quite this unit down? I understand the motor is sealed, but also easily removed and not a unique part as I’ve seen ones like it in other clocks not made by Sankyo. Is there a modern replacement for it? If you can see any other points in the mechanism that could be quieted, please let me know. Thanks!

 

[davefr]

I've had a few requests for these Sanyo motors over the years and as far as I can tell they're unobtainium. They're fairly similar to Telechron but there is not a drop in replacement that I know of.

As a very last resort you may be able to quiet yours down. Just grind (not drill!!!) a little slit in the corner of the rotor's case with a Dremel tool (as indicated) and inject about .5 cc of lightweight oil using a hypodermic needle. (synthetic ATF fluid is a good choice or common 3 in 1). It can quiet it down but obviously won't do anything if bushings and gears are worn. Seal up the slit with sealant.

You can usually buy a 18-22 gauge hypodermic syringe from any farm store for about $1.

 

[Mark286]

As a very last resort you may be able to quiet yours down. Just grind (not drill!!!) a little slit in the corner of the rotor's case with a Dremel tool (as indicated) and inject about .5 cc of lightweight oil using a hypodermic needle.

What kind of Dremel bit should I use? I have a metal cutting disk like the ones attached. Would that work?

 

[davefr]

What kind of Dremel bit should I use? I have a metal cutting disk like the ones attached. Would that work?

View attachment 676668

That would certainly work. Only do enough to generate a tiny hole. And nothing should be injected into the rotor except lightweight oil and don't go more then .5cc. If you want, you can heat up the rotor slightly (150 F) and turn it over a few times to distribute the oil but it should do that on it's own as long as it still runs. YMMV but these low torque rotors are worth a try when the only issue is noise.

 

[Mark286]

YMMV but these low torque rotors are worth a try when the only issue is noise.

Just curious, how quiet should these motors be when running optimally? This one is about 41db right now, or as loud as a loud refrigerator hum. I’ve had old Wesclox that ran almost completely silent, so that’s my comparison.

 

[davefr]

Just curious, how quiet should these motors be when running optimally? This one is about 41db right now, or as loud as a loud refrigerator hum. I’ve had old Wesclox that ran almost completely silent, so that’s my comparison.

When you remove the motor from the clock, you should not hear it run at any more then a couple inches from your ear.

 

[Mark286]

When you remove the motor from the clock, you should not hear it run at any more then a couple inches from your ear.

Should I try to remove the old oil at all?

 

[davefr]

Should I try to remove the old oil at all?

No, the only way would be complete disassembly and cleaning.

 

[kdf]

Could it be mains hum, coming from the coil? Check if the coil and stator are not loose... I have same clock and it's silent.

 

[Mark286]

Could it be mains hum, coming from the coil? Check if the coil and stator are not loose... I have same clock and it's silent.

It’s definitely the motor. When i initially got the clock it wasn’t running, probably because the grease needed to warm up. The power was only audibly when I put my ear up to it. I’m probably going to do the surgery tomorrow. I’ll let you know how it goes.

 

[Mark286]

Ok. I broke a few rules and got the rotor running completely silently. I drilled a hole in the casing and flushed the inside with 91% alcohol. Didn’t get much if any of the old oil out, though, even after heating the rotor up in the oven for 20 minutes. I added 2ml of clock oil and sealed it with epoxy. Sounds as good as new.

 

[davefr]

Ok. I broke a few rules and got the rotor running completely silently. I drilled a hole in the casing and flushed the inside with 91% alcohol. Didn’t get much if any of the old oil out, though, even after heating the rotor up in the oven for 20 minutes. I added 2ml of clock oil and sealed it with epoxy. Sounds as good as new.

2 ml + alcohol? That's about 4X+ what that unit should have and alcohol is not a lubricant. Clock oil is also the wrong lubricant for these motors. Too much oil will reduce the torque and cause it to run slow. However if it runs that's the main thing.

 

[Mark286]

2 ml + alcohol? That's about 4X+ what that unit should have and alcohol is not a lubricant. Clock oil is also the wrong lubricant for these motors. Too much oil will reduce the torque and cause it to run slow. However if it runs that's the main thing.

I flushed the motor with alcohol, I didn’t leave it in. Sorry if that wasn’t clear. I removed all the alcohol and even dried it with an air compressor before adding the oil. However, I am having torque problems now. After an hour of running the clock stopped altogether. I removed the rotor and it runs, but I can stop it with my finger lightly pressed against it. I removed most of the oil I put in, but it’s still not producing enough torque to spin the clock dials for more than a minute. Any way to fix this?

Also, it looks like this is not a sealed unit, but glued shut with some kind of white epoxy. Is there a way of removing the epoxy to access the internals incase it needs a thorough cleaning/maintenance?

 

[EscapeWheel]

This epoxy company webpage has instructions on how to remove it. Scroll toward the bottom.

Epoxy: how to use and remove (unibond.co.uk)

 

[kdf]

You can try to flush it with benzinum medicinale or some other organic solvent. Epoxy can be removed by heat, but if there are some plastic parts inside it could be very riskant...
I would use some ordinary car engine oil like 0W30 or 5W30 for example.

 

[Mark286]

I got the rotor open by dremeling off the epoxy. The mechanisms lifted right out. Everything looks in good shape. The plastic gears are in one piece and the teeth on them and the metal gears look as good as new. I cleaned out all the sludge I could with alcohol. So it’s clean, but a bit greasy. I put it back together without sealing it and it’s running as well as it was when I got it. On time but mildly loud. Taking a look at the mechanism, what oil would be best and how much should I use?