1219 Speed, Pulley, Idler Issue

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nebulix
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1219 Speed, Pulley, Idler Issue

Post by nebulix » 11 Mar 2019 02:02

Forgive me if this topic has been covered before. My searches haven't turned up this exact condition.

I have adjusted the speed on my 1219 as per the manuals, setting the speed adjustment knob to the centre position and
adjusting set screw (116) to align the idler wheel in the middle of the pulley step. This results in slow speeds with the strobe disc, on all three steps. The only way I can get the 33 RPM speed spot on, is to adjust the idler wheel so that it just rides on the top rim of the 45 RPM pulley step.
1219 Spindle.jpg
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This is no good because a) the speed is not stable in this position - it either creeps faster or slower, and b) I'm afraid of wearing a rut into the bottom of the idler wheel.

I suspect that the pulley has been worn down or perhaps the idler wheel itself. Does this make sense? Or should that cause it to speed up?

Alec124c41
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Re: 1219 Speed, Pulley, Idler Issue

Post by Alec124c41 » 11 Mar 2019 03:12

The actual size of the idler wheel is not critical.
Have you cleaned and lubricated all rotating parts? This means motor bearings, idler axle, and platter bearings.

Cheers,
Alec

nebulix
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Re: 1219 Speed, Pulley, Idler Issue

Post by nebulix » 11 Mar 2019 03:16

Yes, it's all been thoroughly done. I think it has to be the pulley itself. Perhaps it's been sanded down or something.

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Re: 1219 Speed, Pulley, Idler Issue

Post by Spinner45 » 11 Mar 2019 04:53

nebulix wrote:
11 Mar 2019 03:16
Yes, it's all been thoroughly done. I think it has to be the pulley itself. Perhaps it's been sanded down or something.
There's no need for anyone to sand down that motor pulley, if someone did, they're an idiot.
The surfaces of it should show a nice polish on each step with no grooving.
Manually spinning the motor with the fingers, it should spin for a few moments, and come to a "rocking back and forth" stop.
If not, the motor needs service.

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Re: 1219 Speed, Pulley, Idler Issue

Post by nebulix » 11 Mar 2019 05:34

Indeed. There are a lot of idiots out there selling "fully-serviced" Duals.

You think it could be the motor? I'll try that spin test on it. Thanks.

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Re: 1219 Speed, Pulley, Idler Issue

Post by mrow2 » 11 Mar 2019 07:30

If the pulley has no grooving and is shiny, pretty and smooth, that might be an indication it has been "dressed (sanded)." Normally there might be a sign of a groove where the optimal speed setting was. Yes, if it was sanded to excess (would not take much) then it could affect the speed range. They are soft and do show wear (grooving). If the motor was not properly serviced with the right oil in the bearings, it's possible that it might be slow. The clamshell bolts should not be over tightened as that could create a little unwanted friction (on some) but I imagine the motor would get pretty hot in that circumstance. The idler wheel can be "dressed" and it's recommended to do so for several reasons, if it's not done to excess but it should not be the cause of the speed question. The platter can be checked and gently dressed with a fine grit paper all around, then cleaned with alcohol/soft cloth. In any event don't allow any fingerprints to be placed on it.

You could obtain a new pulley if in doubt; it might just solve the problem. It must be the correct part number for your 1219, and I believe it is 218-276 but regardless, be sure it's for 60Hz. Someone else could verify the pulley number.

If you are using a heavy record clamp, it does place some stress on the entire drive system and probably causes a bit of extra wear.

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Re: 1219 Speed, Pulley, Idler Issue

Post by samba » 11 Mar 2019 13:39

As the motor has been serviced, I assume the error is not with the motor speed.
As mentioned before, the inner rim of the platter must be clean, as well as the pulley and the idler (no grease).
Have you dressed the idler as described in the service guide?
Further, I assume you checked that threaded pin 118 is thightened well.

This leaves the pulley diameter as suggested before.

Does the platter turn too slow or too fast when the idler is in the proper position?

It could be that you have the wrong pulley, a 50 Hz instead of a 60 Hz (or vice versa), but I do not think it is the case.
A 50 Hz spindle has a larger diameter than a 60 Hz. If you use a 50 Hz spindle at 60 Hz, it will result in a higher linear velocity which will be transfered by the idler to the platter. In that case, you would have had to move the idler upwards.

If I look at your sketch, the speed was probably too low as you needed to adjust the pulley to an area of the pulley with a larger diameter. If the pulley was machined down in diameter, you would need to adjust the idler as you did.

You can check the dimensions of the pulleys in this thread: viewtopic.php?t=91677&start=45#p790921

This is all of course assuming that you just got the machine and do not know about its maintenance history, if you had it for a long time and it ran fine before, something else is wrong.

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Re: 1219 Speed, Pulley, Idler Issue

Post by nebulix » 11 Mar 2019 15:27

Thank you all for the excellent tips.

I rebuilt the motor exactly as in Klaus' motor guide, and it's not overheating. I slightly dressed the idler wheel in a drillpress at high speed.

I've re-lubed the entire speed control mechanism, as well as the idler bushing and arm. The inside rim of the platter, idler and pulley have all been cleaned with isopropanol. The thing is, with idler in the middle of the step, the TT works perfectly -- it's quiet, the speed is stable, motor runs cool -- it's just too slow.

It's always had this problem and the pulley looks like bright shiny brass, as in "new", so I believe it may be suspect. Thanks Klaus, et al, for the pulley dimensions. I will check it with the calipers and hopefully solve this mystery.

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Re: 1219 Speed, Pulley, Idler Issue

Post by tep392 » 15 Mar 2019 17:42

Are the 45 and 78 speeds ok?

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Re: 1219 Speed, Pulley, Idler Issue

Post by mrow2 » 15 Mar 2019 21:31

Conduct a search for a new old stock replacement pulley. tep392's question could have relevance here, i.e. if those readings are better, it points to wear on the existing pulley. Pulleys are occasionally available; wouldn't hurt. Anyone: Seems like I've read that mains fluctuations or under-volt can affect speed (since the utility is continually balancing demand with supply), i.e. what a strobe reads in the AM might not be the same as in the evening? What is the actual line voltage reading of the OP's particular location if this is relevant?

If it is posted above, I didn't see it. Just how slow is the speed at 33.3rpm setting with idler in the middle of the pulley?

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Re: 1219 Speed, Pulley, Idler Issue

Post by Spinner45 » 16 Mar 2019 00:20

On those Duals, the idler must be centered on each motor step with the pitch control also at center.
Thus when turning the pitch control through its full range, and observing the idler, it must go through its full range of "high to low" on that particular the motor step.
There are some details in the service manual pertaining to that I believe.
And of course, the retaining washer must be snapped back onto the idler, keeping it from shifting.

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