Won't self start nor keep runnin'

[bangster]

This concerns the clock in the "Do synchronous motors go bad?" thread.



After my most recent episode of Fixing It , here's what it does:

Most of the time, maybe 3 out of 4 or more, when plugged in it starts right up. Other times, it just twitches and then sits there. A push makes it go.

But whether it starts by itself or with a push, it only runs for a bit —less than a minute— and then stops.

Why?

Here's what I did. I pulled off the rotor from its shaft, and managed to get the gear case unsoldered and opened up. Nothing much interesting in there —none of the deposits of crud we supposed might be there. Just a little 3-gear train. I opened it up, cleaned everything with solvent, pegged out the pivot holes, lubed it and put it back together. Popped the case together, but didn't solder it: neatly wrapped plastic tape around its perimeter to hold it together.

Put the rotor back on the shaft, put everything back together, and plugged it in. A twitch, but no run. OOPS, rotor on upside down. Pulled the rotor back off, put it on right, put everything back together a second time. We are now up to the problem I described above: self-start erratic, WKR (won't keep running).

Stoppage occurs no particular place in the rotation of the drive pinion. I can see the end of the pivot that it drives, and marked it.

Whaddya think? Is it likely to be an electrical problem or a mechanical problem? And what should I do about it?

bangster

 

[harold bain]

Bang can you run it with no load? If it still won't run reliably, your problem is still the motor. If it will, then look for a mechanical problem overloading it. These motors should always self start.

 

[bangster]

I'll make a note of that. But before this latest fix, it ALWAYS self started and ALWAYS kept running...just at the wrong speed. I haven't done anything between the plates to change that.

Only mechanical thing I've fiddled with is the gearbox of the motor.

Hmm.

I didn't oil up everything in the gearbox; just the pivots. Should I drench the whole train?

bangster

 

[harold bain]

Bang, I don't know about this rotor, but the ones I am used to working with came with an "oil bath" environment inside the casing. You should have seen a lot of dried up gummy oil inside the rotor if this is how it started life. But I don't think this is your problem (lack of oil), as this would only make it wear out faster. Did you check the bushings on those pivots in the rotor?