# X axis 150 servo Problem



## Gman45acp (May 26, 2021)

I have a 150 Servo that is on a mill that has seen little use.  The servo will not do anything.   Turning on the switch and the power light does not come on.    I took it apart and every thing in side looks fine.    Does anyone have a schematic for this servo?   I think it is not getting power as I used multimeter to check continuity between the plug and then where those three wires connect to the circuit board and on off switch.   Cannot get continuity on any of the wires, and I have a hard time thinking the factory plug is bad or the cord is damaged as it looks like new.    Any help or ideas greatly appreciated 
if I should be asking this question on another forum in the group, please advise which forum would be the correct place.


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## Nutfarmer (May 27, 2021)

First thing I would check is the limit switch that is activated by limit stops mounted on the front of the mill table. If the limit switch is activated it will cut power to the feed motor. Then try manually jogging the servo. If that doesn't work make sure there is power to the servo. Lastly look for a fuse inside of the servo.


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## hwelecrepair (May 27, 2021)

Even with the limit switch depressed, you should get power to the circuit board.  The power wires should go black to the "circuit breaker" which then connects to the red wire on the circuit breaker when it is on that goes to the same blue connector that the white wire of power goes to.  You should be able to get a short from the plug to the black wire and to the white wire.  

This is a brand new Servo 150?  Or new to you?  The diagram that comes with new Servos is definitely lacking.  Can you post pictures of how your connectors are attached to the circuit board?

Jon


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## Gman45acp (May 28, 2021)

hwelecrepair said:


> Even with the limit switch depressed, you should get power to the circuit board.  The power wires should go black to the "circuit breaker" which then connects to the red wire on the circuit breaker when it is on that goes to the same blue connector that the white wire of power goes to.  You should be able to get a short from the plug to the black wire and to the white wire.
> 
> This is a brand new Servo 150?  Or new to you?  The diagram that comes with new Servos is definitely lacking.  Can you post pictures of how your connectors are attached to the circuit board?
> 
> Jon


This is new to me.   I will check again and try to post picture of the meter and where the probes are touching.  Should get that done today


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## Gman45acp (May 28, 2021)

Gman45acp said:


> This is new to me.   I will check again and try to post picture of the meter and where the probes are touching.  Should get that done today


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## Gman45acp (May 28, 2021)

So I put one multimeter probes from the spades on the 110 plug and the other to each of The wires shown in the Picture.  None would show short.   Then went did the same thing using the other two spades on the plug and back to all the same wires.    No short shown.    When touching The multimeter probes together it goes to zero So that is working correctly.    The black switch on the lower  left  ( on off switch) works.    Shows open and closed on meter When it is moved.   The on light on the circuit board looks like may be burned out as it is dark and touching the meter probes to the two exposed Legs does not show a short.    Also the high speed micro switch shows closed in all combinations of touching the three legs with the meter probes, so that can’t be right.  So I plugged it in to wall plug set multi meter ate 120 volts and touched the black wire on the on off switch and the white wire with multi meter probes and no voltage.   I still can’t believe it is The feed line that is bad.


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## Gman45acp (May 28, 2021)

Found parts diagram and it shows a fuse on the parts list but then does not show it in the part diagram.  I looked and can’t find any fuse at lease not the kind I am used to looking for.


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## Shootymacshootface (May 28, 2021)

The on off switch on the bottom is also a circuit breaker. Those go bad.


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## Gman45acp (May 28, 2021)

Shootymacshootface said:


> The on off switch on the bottom is also a circuit breaker. Those go bad.


With multimeter probes on the contacts and the flipping the switch it closes and shows that the switch is making contact, don’t know if that means it is working properly.


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## akjeff (May 29, 2021)

If you've got no continuity from the prongs on the plug to the other end of the power cord, I'd get to the bottom that before going any further.


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## hwelecrepair (Jun 3, 2021)

The green wire on the plug you pointed at in your picture, that is actually coming from the limit switch and has nothing to do with ground.


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## Gman45acp (Jun 3, 2021)

Got it working.   The power cord was completely pulled apart where it goes into the housing at the strain relief.   Must a
have been quite a pull to do that.    Everything works buy it surges at mid speed and when you first turn the speed control.  Turn it a little more and it smooths out then does it again between 5 and 6 then runs fine after that.    I can live with that unless someone knows it is a easy fix.    High speed traverse button work correctly.


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## akjeff (Jun 3, 2021)

Excellent! The speed control potentiometer may be "noisy". See if you can get a squirt of contact cleaner inside, if there is an opening somewhere. Also, you could try vigorously turning the nob back and forth repeatedly in the erratic sections, as it might break the corrosion on the contacts. Good luck!


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## hman (Jun 4, 2021)

Gman45acp said:


> Got it working.   The power cord was completely pulled apart where it goes into the housing at the strain relief.   Must have been quite a pull to do that.


I could imagine the cord getting snarled/caught somehow during power feed.  There's plenty of power there to stretch/break any cord!  Happy to hear that you were able to find and fix the problem!


Gman45acp said:


> Everything works buy it surges at mid speed and when you first turn the speed control.  Turn it a little more and it smooths out then does it again between 5 and 6 then runs fine after that.    I can live with that unless someone knows it is a easy fix.    High speed traverse button work correctly.


+1 to what @akjeff said.  As I recall from a similar unit I once had to repair, the pot had a super-long shaft, and replacements were pretty scarce.


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## sdelivery (Jun 4, 2021)

Parts for Servo brand feed units are available from HIGH QUALITY TOOL  they still repair SERVO brand feed units at their plant in Cleveland Ohio.
This is where they started decades ago.
Their catalog includes parts break downs.


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## hwelecrepair (Jun 4, 2021)

I would clean the armature and let the unit run at 100% speed to ensure the brushes are properly rounded to the armature.  

I have seen it alot when adjusting a speed quickly that it will kinda surge.  But I also see that happen with a dirty motor.


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## Gman45acp (Jun 4, 2021)

sdelivery said:


> Parts for Servo brand feed units are available from HIGH QUALITY TOOL  they still repair SERVO brand feed units at their plant in Cleveland Ohio.
> This is where they started decades ago.
> Their catalog includes parts break downs.


H&W Machine repair has the pot with the long shaft list on their  parts web site.   11.95.   Will order it and I agree that the pot is probably the problem.    That power feed is nice to have, saves a lot of cranking.


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## Gman45acp (Jun 4, 2021)

hwelecrepair said:


> I would clean the armature and let the unit run at 100% speed to ensure the brushes are properly rounded to the armature.
> 
> I have seen it alot when adjusting a speed quickly that it will kinda surge.  But I also see that happen with a dirty motor.


When I had it apart I had  the brushes out.   The looked good and were rounded to the armature, and the armature looked good,  but will give that a try before I order the Pot.    Thanks for reply


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## Gman45acp (Jun 4, 2021)

Well all is good now.  I ran the table back and forth several times at high speed.   Turn the speed knob  full range back and forth for a couple of minutes Woth unit turned off.  The turned it back on and now it works as it should, smooth in all speed ranges, from as slow as it will go to as fast and all speeds are now steady and smooth.    It fixed its self Go figure.   Thanks to all that responded


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## akjeff (Jun 4, 2021)

Outstanding! Enjoy the convenience and the great surface finish that goes with it!


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