HAAS VF2 Mill

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bruski

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Has anybody got some experience with a 1992 Haas VF2 mill. I got a alarm message 175 which states that there could be a ground fault with one of the servo motors or tool changer motors or possibly the oiler. The service manual said that carbon dust from the brushes could cause arcing. I blew out the brushes on all three servo motors with compressed air already, lots of dust but still no working. I can't move any servos because they are shut off until the ground fault is corrected. I don't know what else to do after checking the wiring harnesses and all of the fuses which are all good. These machines are so sensitive and stubborn some times. In order for the system to initiate this alarm, there needs to be at least a half of an amp short somewhere which should have blown a fuse somewhere. I wonder if maybe there is a fault with the ground fault circuits.
Any help would be great,
Thanks,
Mark
 

fcheslop

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From memory, the cooling fans also come under that code as does the 115V power supply
Thats all I can remember about them although the fan was a common culprit as the company used a lot of Graphite
 

bruski

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I will check the fans for any problems. Thanks for your help.
 

fcheslop

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Failing that try disconnecting one motor or ancillary at at time to see if it will reset you will get a error code for what ever has been disconnected but the error 175 should go
It was in the 1990 working for a company named Perlos that I did a little work on those machines
I do remember a different fault with the auto tool changer they often timed out due to dirt or a little wear and tear and the locking time could be altered in the machines constants .
Good luck
 

bruski

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That is a good idea, I will try disconnecting the motors one at a time including the tool changer and see if I can locate which one is ground faulted. I have to install the air and lubricator panel back on the machine first. I will let you know how it turns out. Thanks again for helping me out here.
Mark
 

fcheslop

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You may get an over heat alarm not sure but you can switch off the motors individually in Parameters
I can vaguely remember bits of how to do it but dont want to tell you incorrectly
I do know most of the problems came from the fans , Y axis motor or the the tool changers shuttle motor it used to be the one that hangs of the back. The machines I worked on the shuttle motors cables ran through steel flexible conduits and this is where the earth faults were hiding.Also when we moved the machines the graphite dust used to get rattled about and often you get err175 until the motors were cleaned out and they need to be very very clean. If you test the motor anything under 1meg ohm +or_ to earth is dodgy
Sorry thats about all I can say
You could get better info on the cnc forum
cheers
frazer
 
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bruski

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Yep, The overheat alarms prevent the power from turning on to the servos not letting me know if the ground fault is found or not. I don't think that I am qualified to change any parameters switching off the motors, at least not yet, maybe when I get desperate enough.
How do you test the motors for the 1 meg ohm of resistance? I will try the cnc forum also.
Thanks,
Mark
 

bruski

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Can the motors be tested at the cable plugs where they plug into the cabinet? I can find out which pins are what from the service manual. Then use a digital multimeter set to 1 meg resistance checking each pin that supplies power to the motor with ground. Right?
I checked out the cnc forum, there is a lot of questions asked and not much replies.

Thanks again,
Mark
 

fcheslop

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Yes but remember the fault maybe in the cabling and not the motor
You can also disconnect the supply to the motors on the I/O board this way you may not get the over temp
alarm as that circuit will still be intact
From memory
#7 then e/stop the machine takes you into set up. The up down or left right keys change the parameter
1=off
The parameter will stay switched off even after power down so you must remember to reset it
I cannot remember the parameters you need 15 comes to mind for the Y axis but its nigh on 30 years since Iv seen one of these machines
What was the machine doing when the fault occurred
! tool changing
2 cutting axis ?
3 did you have a crash
 

bruski

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I was showing my employee how to jog and how the tool changer works. I turned the power on with green button upper left of front panel, then pushed the auto power up next to the reset button. The machine zeroed all axis after that, I pushed the handle jog button then .01 button followed by the x axis button. Then moved the x axis to the right with the jog wheel and centered the table followed by pushing the y axis button and centered the table that direction. I then pushed the MDI button then typed T2 followed by pushing the ATC FORWARD button. The tool changer moved into position and did the tool change putting tool number 2 in the spindle. I was finished showing him how it worked and pushed the auto power down button. There was no movement of the table or tool changer during power down which I though was weird as it counted down then shut off. It usually puts the tool away then moves everything back to zero positions. The next day I was going to power up the machine same as usual pushing the auto power up button but nothing happened because of the alarm message 175 preventing servo power.
I should mention that I just got this machine a few weeks ago and it traveled about 400 miles on my trailer the whole way. Smooth ride the entire trip and it was running normal for several power ups before this happened but never made any chips yet. I have jogged the machine in all axis several times already and did several tool changes without any problems before the ground fault problem.
I wouldn't mind investing a little money money in some parts for this machine but HAAS doesn't seem to have anything for a 1992 machine. I was trying to get a coolant pump and tank for it with the low coolant sensor in it and could not find anything from there web site.
Thanks again,
Mark
 

fcheslop

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I think the problem could be carbon dust as we used to get problems when the machines were moved around a toolroom . They take a bit of cleaning with an air gun and a shop vac. The test meter will show it up
I would go for the shuttle motor first and please check its cables if it has the flexy steel conduit it wears through the insulation
The test is on the motors+ and - to earth
Sorry but that is about all I know or can remember
Was the low level just a simple float switch if the input is set up you could add one and switch on the constant in set up but get the beggar to run first
 

bruski

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The X axis is reading 5.38 megs all the other supply feeds showed nothing or zero. At least that servo motor is a little bit easier to get at. I have the enclosure sides removed already. The cable for the x axis is going to be a tough one though because it runs beside the y axis lead screw and then winds up into the table along side the x axis lead screw. I am willing to bet that is where the insulation might have a problem. I will tag and remove the wiring from the motor and check it again to see if it is the cable or the motor with the fault.
Thanks for all of your help fcheslop so far, I have a feeling that the fault will be exposed soon.
Mark
 

kf2qd

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Ran a LeBlond TapeTurn lathe many years ago - had to take the motors apart and wash them out with electrical cleaner. 2 cans a motor. Lots of carbon, but they behaved afterwards.
 

bruski

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Here is a recap after re-booting my meter. As it turned out the x axis is ok at 5 megs. The bad motor is the Y motor or cable at 4.3 K ohms. After re-reading your reply stating anything under 1 meg. ohm would be bad. At least that cable is easy to check after I remove the air and lubricator panel again.
Thanks kf2qd, I will probably be washing the Y axis motor out if that is what it needs. I am going to replace the brushes in all three motors also on Thursday when they arrive.
Thanks again, I will get back to reply when I figure things out here or if somebody comes up with something else.
Mark
 

fcheslop

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That is good news and at least it looks like youre chasing it down
Those motors do take a lot of cleaning and after a good road run Im not surprised
I would do as you say and split the motor from its cable and test to see if its motor or wiring
Also if you are blowing the motor out with compressed air it needs to be dry air
Yep you soon get sick of removing the panels
cheers
frazer
 

bruski

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HI,
I separated the motor from the cable and the fault is in the motor. I was able to remove the coupling end bearing housing then separate the magnet housing from the brushed end ok. The armature looks ok to me nothing burnt etc. Not sure if I want to remove the encoder from the other end because I don't know how to time it to the armature. I think that I should probably send it off to a repair service that does servo motors.
Mark
 

fcheslop

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Before you send the motor to the repair shop. Check the brush holders with youre meter as Iv seen the insulator break down on similar motors
From memory I think the encoder is an etched glass disc so be careful
Nice to see its on the mend
 

bruski

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Sorry fcheslop, before I noticed your last post, I had already sent it off. The new brushes that I got for the other motors are now installed. Waiting on the quote for the other motor now. I think that I came up with a way to get around the over heat sensor. It is a normally closed switch, so a jumper between the two pins in the receptical would get around it. But I really don't want to try and boot up the machine without the y axis motor in it and mess up something while it tries to go zero home. Nothing to do but wait now.
Mark
 

fcheslop

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Hi, I dont have any wiring diagrams so cannot comment. I used to simply switch the motor off in the set up ,This allowed the rest of the machine to function but its a long time past
I had a look in the workshop to see if I had kept my old notebook for the HAAS machine but no luck plenty for Engel,Klockner and Fanuc and loads of Coffee machine junk
Glad to hear that you seem to be heading in the right direction and hope this is the cure
Thanks for the update
cheers
frazer
 

bruski

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The repair shop finished working on the servo motor. The ground fault was in the brushes they said. Still waiting for it too arrive and get installed.
bruski
 
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