[alpydawg]

I recently purchased a '98 haas VFE. This is my first "real" cnc mill, I've been running a 3 axis DIY CNC grizzly mill for the last 7+ years and it was time to get something bigger. It was delivered a couple weeks ago to us by a CNC freight company. Trip was only about 30 miles. We had a CNC service company come in and level the machine and set everything up. Everything seemed to be working fine when the tech was here as well as when we initially inspected the mill prior to purchase. I've been learning the basics (turning machine on, loading tools, manual jog the axis', running chip auger, etc..) but I have not cut anything on it or even run a program yet. I was in the process of setting up tool offsets when I stepped away from the machine for about 30 mins and when I returned the alarm was on and the 175 ground fault detected message was on the display.

The machine has relatively low hours on it for the year. The commands window shows Power on time: 7037 hrs, Cycle Start Time: 1215 hours, Feed cutting time: 908 hours
The guy we purchased the machine from said he replaced the tool changer shuttle motor a couple years ago.

Any ideas on where I should start looking for the cause of this ground fault? I opened up the back panel and there doesn't seem to be any fried components that I can see. Could a loose connection from transport cause this fault code?

Any help or insight would be much appreciated.

[alpydawg]

So I am trying to isolate where the ground fault is coming from by disconnecting each of the motors called out in the manual associated with this fault. I have disconnected the tool changer turret and shuttle motors to see if this would make the ground fault code go away. No luck... I tried disconnecting each of axis servos individually from the side of the control box, but when I turn everything back on I get a bunch of other alarms. I'm not sure if these new alarms override the ground fault? Is there another way to disconnect the x, y, z axis servo motors to see if the ground fault alarm will go away?

The manual also say that it could be the fan motors or the oil pump. Is there an easy way to disconnect these as well?

This is my first Haas so I'm not very familiar with where all the connections are.

Thanks in advance for any advice.

[alpydawg]

I found the service manual on line and have been able to disconnect the fans, oil pump, turret and shuttle motors from the I/O PCB. The 175 ground fault detected is still present, so I guess that leaves me with the servos?
When I disconnect the x-axis servo I get an overheat alarm, so I can't tell if the x-axis servo is causing the short. Is there a way to turn off the overheat alarm so I can see if the ground fault alarm is still present?

[alpydawg]

I have now cleaned the carbon dust from brushes on the x, y, z servos. Still getting the ground fault detected??? Anyone out there have an idea what I should try next?

[alpydawg]

If I disconnect P5 from the I/O PCB the fault goes away. This is the servo power. Question now is which servo is causing the short? Is there a way to disconnect each drive individually without getting the overheat alarm?

[Machineit]

I feel bad that you are not getting any help, but I have no experience with this particular fault. Most of these I think come from motor or cable faults, but I don't know if you can disconnect each to find the fault. Hang in there and someone with more knowledge will jump in. Funny, but they seen to jump in and fight for attention on many threads and then sometimes just don't show up for weeks.


Mike

[alpydawg]

Mike, thanks for the response. I think I have made a little more progress. I found a wiring diagram in the service manual for the servos and identified the motor +, motor -, and ground wire. On all motors + to - I get around 2 to 3 ohms, which I think is good. When I measure + to ground and - to ground on both x and z I get no reading but on the y I get about 318 ohms. So I think this means I have a short to ground in the y servo or cable? I'm a mechanical guy and only know enough about electrical to not electrocute myself... can anyone with more electrical/ motor knowledge out there confirm that this is consistent with a short in the y servo or cable?

[Machineit]

Well, since I can't help you directly, I'll just tell you an interesting story.

Many years ago, I worked at a large industrial grinding house in California. The main building was about 15,000 square feet and had dozens of various grinder in it, to include custom made double disk grinders and Blanchards with up to 6 foot diameter tables. Probably about 20 machines in all and all running on 440 three phase. I did the maintenance and built and rebuilt them, did all the electrical and etc.

The entire building was on an electrical panel back near my office. It had a ground fault detection system in it and when a fault was detected, it took out the entire build that instant. I would have to wait about 15 minutes for the lights to cool down, Metal Halide I think, then I could power the building back up. To do that, I would go to the main panel and pump a foot pedal about 15 times. That charged the engagement circuit and then when I hit the power button, it sounded like a small car crash. Thousands of amp ran through there.

I all of the years I was there, I don't think any machine was ever responsible for the fault, it was always someones little radio that had gone bad and had just been plugged into a simple 120v outlet. Most of the time it was just a break for the employees and everyone went outside in the sunlight and waited, but once in a while when there was a large chunk of metal in one of the Blanchards and the residual magnetizem in the chuck was unable to hold the part during the heavy cut, we could have some spectacular crashes and all would be diving for cover.

Good luck on you search, but it does seem like you are getting there.

Mike

[haastec]

Mike, thanks for the response. I think I have made a little more progress. I found a wiring diagram in the service manual for the servos and identified the motor +, motor -, and ground wire. On all motors + to - I get around 2 to 3 ohms, which I think is good. When I measure + to ground and - to ground on both x and z I get no reading but on the y I get about 318 ohms. So I think this means I have a short to ground in the y servo or cable? I'm a mechanical guy and only know enough about electrical to not electrocute myself... can anyone with more electrical/ motor knowledge out there confirm that this is consistent with a short in the y servo or cable?

Based on your numbers it does appear that your y-axis motor/cable is the culprit. And to answer an earlier question, to disable the axis so you do not get the overheat alarm you would want to find for Y-Axis, Parameter 15 bit 3. Toggle DISABLED to a 1. With this parameter changed, you can now unplug the motor cable at the electrical cabinet without any overheat alarms.

Repeat your measuements at the y-axis motor with the cable disconnected from the motor and see if you get the same results.

Hope this helps.

[alpydawg]

Based on your numbers it does appear that your y-axis motor/cable is the culprit. And to answer an earlier question, to disable the axis so you do not get the overheat alarm you would want to find for Y-Axis, Parameter 15 bit 3. Toggle DISABLED to a 1. With this parameter changed, you can now unplug the motor cable at the electrical cabinet without any overheat alarms.

Repeat your measuements at the y-axis motor with the cable disconnected from the motor and see if you get the same results.

Hope this helps.

haastec, how do I toggle DISABLED to a 1 in this menu?

[haastec]

haastec, how do I toggle DISABLED to a 1 in this menu?

Turn setting #7 to OFF
Then place the machine in E-Stop
In parameters, Highlight the parameter to toggle
Type in the number 1
Then press ENTER

[Machineit]

Turn setting #7 to OFF
Then place the machine in E-Stop
In parameters, Highlight the parameter to toggle
Type in the number 1
Then press ENTER

Setting 7 is under "SETTING GRAPH" and the parameter is in "PARAM DGNOS" for clarification.

In parameters, you sometimes hit the up and down arrows to move up or down and sometimes you hit the left right arrows to move up and down. Just so you know. And turn setting 7 back on when you are done.

Mike

[alpydawg]

Mike, Haastec,

Thank you. I was able to get the y axis toggled off and this made the 175 alarm go away, so I'm 100% certain it is the y axis now.

I did pulled the brushes off the y axis again and vacuumed/blew shop air to see if maybe there was still carbon dust in there. I put it back together and still get the ground fault. I measured the resistance from ground to motor + and motor - and the reading has gone from 318 ohms to 1.2kohms. I think this would mean that there is still some carbon build up causing the short, but it isn't as clean a path to ground? Does this make sense to anyone else? I think I'm going to to try and clean a little more and see if it solves the problem.

[Machineit]

Makes sense I think. The carbon may have been dislodged during shipment. Keep cleaning and maybe you won't have to remove and disassemble. Try to use dry air too. If you have a shop vac, use it on one side and the air on the other.

Hmm, 1998 and you have brushed servos, I think most were brushless? Mine is for sure.

Mike

[haastec]

Mike, Haastec,

Thank you. I was able to get the y axis toggled off and this made the 175 alarm go away, so I'm 100% certain it is the y axis now.

I did pulled the brushes off the y axis again and vacuumed/blew shop air to see if maybe there was still carbon dust in there. I put it back together and still get the ground fault. I measured the resistance from ground to motor + and motor - and the reading has gone from 318 ohms to 1.2kohms. I think this would mean that there is still some carbon build up causing the short, but it isn't as clean a path to ground? Does this make sense to anyone else? I think I'm going to to try and clean a little more and see if it solves the problem.

Make sure you double check your resistace measurements with the motor cable connected and disconnected to make certain the cable is not bad also; sounds like it is just the motor, but always good to verify.

IMO, any DC motor under 1meg ohm (+ or - to ground) is on it's way out; how long it takes can vary greatly. A brand new motor should read infinity on a multimeter if that says anything.

If you want a long term fix, pull the motor, disassemble and give everything a good cleaning. Test it again by connecting it to the machine while motor is on the floor. If you get good readings then continue to run, if not have it rebuilt or bite the bullet and replace it.

Good luck!

[alpydawg]

Woot! back up and running!!!!! i just needed to clean everything a little more thoroughly. I had originally only blown air in the top brush locations as it was very difficult to get access to the bottom holes. I ended up getting some flexible hose and jamming it into the bottom holes and blowing shop air through the hose. This did the trick. Ohmed out the motor + and motor - to ground and there was infinite resistance. Crossed my fingers when I hooked everything back up and fired up the machine and the alarm was gone!

Thank you so much for the help navigating the haas controller and advice on the motor measurements. I guess on the bright side I know a crap load more about the machine now than I did when I bought it.

[Machineit]

That is Great! Yep, got to get it out and just move it around. Congrats and welcome to the Haas repairman group.

Mike

[haastec]

Woot! back up and running!!!!! i just needed to clean everything a little more thoroughly. I had originally only blown air in the top brush locations as it was very difficult to get access to the bottom holes. I ended up getting some flexible hose and jamming it into the bottom holes and blowing shop air through the hose. This did the trick. Ohmed out the motor + and motor - to ground and there was infinite resistance. Crossed my fingers when I hooked everything back up and fired up the machine and the alarm was gone!

Thank you so much for the help navigating the haas controller and advice on the motor measurements. I guess on the bright side I know a crap load more about the machine now than I did when I bought it.

:wee:

Glad you got her back up and running!:cheers: