Erratic Turntable Speed - I'm Stumped

[CDBPDX]

Got a nice little Columbia portable phonograph. Originally, the problem was a bad spring, turntable would play until you dropped the reproducer, then it slowed to a stop. First thought was the spring, checked it out - it had been broken and welded back together, and wasn't very springy. Got a new spring and installed it - runs great except for erratic speed. Further investigation revealed the governor brake pad mount was rusted and didn't swivel. Fixed that, but it still has erratic speed.

It has one of those half-moon speed adjust setups, everything there seems to be moving properly and in working order. The governor also appears to be working well, good springs, nothing out of balance, and in good condition. The brake pads are well oiled, too.

Still plays at speed for a bit, then slows down, then speeds up too fast, then slows down again.

What's next?

Thanks! Cliff

[gramophone78]

What's next?

Thanks! Cliff

Well, as always....pics are a great start... .

[CDBPDX]

Pictures are worth a thousand words -

[Joe_DS]

I had an identical problem with a Victrola motor once. It turned out to be an improperly seated governor. Make sure that there is no noticeable movement or shake in the direction of the arrow.

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It should be free to spin, of course, but if it moves back and forth along it's shaft, the speed will fluctuate.

HTH,
Joe

[Henry]

Personally, for starters I like a nice shiny clean mechanism. Once clean, it can then be lubed with fresh oil and gear lube (err on the side of less is better than more). I prefer the Labelle line of "synthetic" oils and gear lubes. These come in several viscosities, and some are plastic compatible, although this is seldom a consideration in our hobby. Labelle is carried by many hobby shops catering to the model railroad trade, and is also available on the internet. I notice that the governor leathers in your photograph are totally saturated with old lube, and I would replace these with new leathers oiled sparingly; this alone might be enough to even out the speed variation. Good luck, and let us know how it all "turns" out.

[CDBPDX]

I had an identical problem with a Victrola motor once. It turned out to be an improperly seated governor. Make sure that there is no noticeable movement or shake in the direction of the arrow.
It should be free to spin, of course, but if it moves back and forth along it's shaft, the speed will fluctuate.

HTH,
Joe

There is only the tiniest bit of movement along the shaft axis. I think any less would start to pinch the shaft. That was one of the things I checked. That being said, I did nothing to the governor shaft, assuming it was OK. Probably should see if it will make a difference if I adjust it a little.

Thanks! Cliff

[Curt A]

The governor shaft could be a little too tight, which would also make the speed erratic... Also, make sure the speed control is not slightly bent which might make the leathers touch intermittently, if that makes sense...

[Brad]

It is difficult to tell the nature of the erratic speed from your description. If it varies over a period of several seconds, it could be something in the gearing or spring barrel. Try observing the positions of all the gears and the barrel when the speed changes and see if you notice a correlation between the time it take a gear to rotate one revolution vs when the speed varies. If you observe a correlation, that is the area to focus.

[CDBPDX]

It is difficult to tell the nature of the erratic speed from your description. If it varies over a period of several seconds, it could be something in the gearing or spring barrel. Try observing the positions of all the gears and the barrel when the speed changes and see if you notice a correlation between the time it take a gear to rotate one revolution vs when the speed varies. If you observe a correlation, that is the area to focus.

All good advice. I tried to correlate the erratic behavior to a specific gear, but no luck. It doesn't seem to follow a cycle. Even kept track of the spring drive gear to see if there was a 'high' spot that might be present, but the speed fluctuations had me making marks all over the spring barrel. In any case, I cleaned and inspected all the teeth of all the gears and they looked to be in good condition. Probably something to do with the governor. I'll let you know what happens when I jiggle it a little.

Cliff

[barnettrp21122]

I'd check the governor pads for any ridges or "shoulders" developed from contact with the outer rim of the governor disc, as noted in the photo below. Smooth any unevenness with an emory board. I had a speed variation problem with a VV-50 and this fixed it. Good luck!
Bob

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