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HELP!: Monarch 10EE Jerky/Jumpy/Stuttering Spindle from 0 - 1,400 RPM

Mac007

Aluminum
Joined
Jun 7, 2009
Location
Kentucky USA
Need Suggestions on what to Check on my 1969 10EE:

The Spindle/Motor Drive Stutters/Jerks/Pulses from 0 - 1,400 RPM after that it runs smooth.

I have replaced all the Module Diodes with new Modern ones.
I have tried locking out the QSD contact, no change.
My Tube Filament Voltage is perfect at 2.5volts.
If I set the RPM at higher RPM’s and stop/start the spindle it smoothly accelerates to the set RPM, no issue.
Machine is a Factory Badged 460 volt. It is powered by 220Volts single phase connected to a Step Up Transformer which is providing 468volts.

Any Suggestions on what to check would be appreciated.

Kind Regards, Ken

 
Is it only jerking and stuttering when you're changing the speed? If so it's possible that there are problems with the armature control potentiometer. You might be able to confirm it by seeing if very fine movements near one of the stutter points can't find a dead spot.
 
Is it only jerking and stuttering when you're changing the speed? If so it's possible that there are problems with the armature control potentiometer. You might be able to confirm it by seeing if very fine movements near one of the stutter points can't find a dead spot.

It does this at any setting from 0 to 1,400. It does it whether the RPM dial is stationary or slowly advancing.

Could it be the FA Relay?
 

It does this at any setting from 0 to 1,400. It does it whether the RPM dial is stationary or slowly advancing.

Could it be the FA Relay?

I don't think it could be the relay. The thing is - from 0-1400 rpm the armature voltage is changing and the field is supposed to be constant, after that the armature is constant and the field is changing. Having the field or the armature changing outside your control could reproduce the effect you're seeing.

Could you video the lathe while it's doing this and put the video up on youtube? It might help narrow down the possibilities.
 
Check your field voltage it should be full voltage at the lower rpm's and that relay should not be kicking in. That relay should only kick in when the motor draws a high current on the armature to apply full field to the motor. Wirh that relay kicking in that tells me that YOU DO not have full field.
 
Check your field voltage it should be full voltage at the lower rpm's and that relay should not be kicking in. That relay should only kick in when the motor draws a high current on the armature to apply full field to the motor. Wirh that relay kicking in that tells me that YOU DO not have full field.

Yup, it's the Quick Slowdown Relay pulling in.

I'd suspect the C3J, the smaller of the tubes in the tube panel.
 
To check this voltage do I probe F2 and 18? Multimeter set on DC.

Documentation say 120 VDC.

If its not 120 VDC, what do I check next ??

Kind Regards, Ken
 
buy and replace the C3J vacuum tube is what he said

https://www.ebay.com/sch/i.html?_fr...cat=0&LH_TitleDesc=0&_osacat=0&_odkw=c3j+tube[/QUOTE


I have already purchased and replaced that tube. But no change.
Not sure how I can tell if the C3J I bought is good, or the one I replaced was good.
What is your field voltage? If not up to 120VDC you have a problem with that circuit and the first thing you do is change the tube which you have done but if your 120VDC is not right that circuit is the problem if your 120VDC is there then you can leave that circuit and look for something else. Also check your field voltage on the motor it self that will tell you if the wiring is good.
 
Have you correctly adjusted the two trim pots in the module, one is for top speed the other is speed compensation?

Yes, I have gone thru that procedure and it corrected an OVER-Reving issue I had. When you set the RPM at say 2,000 and started the Spindle it would over shoot to apx. 3,200 and then settle back at the 2,000 setting.
Now it smoothly accelerates up to the RPM setting without over shooting.
 
What is your field voltage? If not up to 120VDC you have a problem with that circuit and the first thing you do is change the tube which you have done but if your 120VDC is not right that circuit is the problem if your 120VDC is there then you can leave that circuit and look for something else. Also check your field voltage on the motor it self that will tell you if the wiring is good.

Any directions on how / where to check this Field Voltage? Thanks
 
Checking Motor FIELD Voltage: VDC

My Monarch Documentation Package shows the following on the full size wiring diagrams:

Voltage Table:
11DA4AF0-F45D-4F91-883A-1B60A9EB8948.jpg

Can I check the Field voltage off the Terminal Strip on the module shown below?
56D13370-463C-4B32-B1A6-7DCAFEFD759B.jpg
 
Results of Testing:
First Pic is SetUp for Testing Motor Field From -18 & +F2 per the Monarch Documentation Using the Terminal Strip on the Tilt Out Modular Drive Panel.
815CAA42-B871-4734-8081-6324BF698A9D.jpg
After Start up Read 118.8 VDC at -0- RPM, and 119.3 at 200RPM
And 64 at 2000RPM and then after speed it up and back down it was 54.98 at 2000RPM.

Monarch Says it should be 120 VDC at 200 RPM and 57 VDC at 2000 RPM

So what should I check Next ??

Thanks Everyone for you Help :)
 
Looks Good On the field check. Next check the amps on the motor how much it is drawing when not cutting.
 








 
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