Fanuc 18i-MB alarm support

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Berryman1012

Plastic

Joined

Apr 14, 2018

• Apr 14, 2018

• #1

I have a 445 y axis soft disconnect alarm that is haunting my machine. Once it’s starts alarming for the day you might as well power down the machine and go home. We have noticed if you hit the system hard key>diagnostics>search for 200. The column with the letter FBA above it has a 1 in the “Y” row. When not in alarm state it is a 0. Can anyone elaborate as to what that diagnostic number represents???? We are going nuts trying to figure out a solution. And yes the wire has been replaced within the last week. Anything is helpful.

 

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Other Brother

Hot Rolled

Joined

Dec 6, 2014

• Apr 14, 2018

• #2

Definitively a feedback alarm on the encoder. I have seen coolant in a connector at the motor cause this but it could even be a wire on the inside where the encoder is. If you have replaced the cable I would take the cover off and inspect the wires from the connector to the encoder.

 

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Other Brother

Hot Rolled

Joined

Dec 6, 2014

• Apr 14, 2018

• #3

Another possibility is a bad connection on the drive itself. You could try re-seating the board on the drive but you will probably lose the reference position. If you know how set the home position I would try re-seating the board.

 

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Vancbiker

Diamond

Joined

Jan 5, 2014

Location

Vancouver, WA. USA

• Apr 14, 2018

• #4

Berryman1012 said:

....And yes the wire has been replaced within the last week. Anything is helpful.

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So would letting us know what wire was replaced.....

 

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Berryman1012

Plastic

Joined

Apr 14, 2018

• Apr 14, 2018

• #5

Sorry. The wire going from the drive to the servo.

 

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Vancbiker

Diamond

Joined

Jan 5, 2014

Location

Vancouver, WA. USA

• Apr 14, 2018

• #6

Berryman1012 said:

Sorry. The wire going from the drive to the servo.

Click to expand...

There are 2 cables between the drive and motor. One is the motor power and the other is for the encoder. Hopefully it was the encoder cable that was replaced. With that changed and still having the issue, swapping out the encoder is a good next step.

 

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Berryman1012

Plastic

Joined

Apr 14, 2018

• Apr 15, 2018

• #7

Thanks for the insight fellas. I will update in the future once we determine a solution.

 

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Berryman1012

Plastic

Joined

Apr 14, 2018

• Apr 23, 2018

• #8

Update: we swapped encoders on the y and z axis motors. Still getting alarm for y axis. We were sure that it had to be a bad drive. We purchased and installed a replacement drive only to still get the alarm. We returned the drive and put the original drive back on the machine. Now we are troubleshooting the possibility of the glass scale on the y axis being either dirty and/or damaged. Any experience with that or maybe some tips? Thanks in advance!

 

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Vancbiker

Diamond

Joined

Jan 5, 2014

Location

Vancouver, WA. USA

• Apr 23, 2018

• #9

Did you figure out if the encoder cable or power cable was replaced? You can meter out the encoder cable as a quick check. Best to test them under a load, but that gets a bit too complex for most folks to deal with.

 

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Berryman1012

Plastic

Joined

Apr 14, 2018

• Apr 23, 2018

• #10

The cable that was replaced was the signal wire going from the drive to the encoder. After we swapped the encoders and still got the alarm on y axis, we put the encoders back on their original axis. I’m not sure whether it matters or not, but y axis runs off of a 2 axis drive that also powers z axis. This machine is a 3 axis bridge mill.

 

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Berryman1012

Plastic

Joined

Apr 14, 2018

• Apr 23, 2018

• #11

Also I wrote a short M99 loop program to run the y axis back and forth to try to envoke the alarm. We ran this program with the encoders swapped to test and see if the alarm would transfer to z and follow the encoder. But unfortunately it stayed in the y axis.

 

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Berryman1012

Plastic

Joined

Apr 14, 2018

• May 3, 2018

• #12

Update #2

After having a tech come out, we discovered that we have an extreme amount of backlash in the y axis ball screw. We turned the scale off in the parameters and we are running solely on the encoder at this point. After some trial and error we have the parameters adjusted good enough to repeat poison with about a thou or so in y. So as of right now we just have a big bandaid on the machine. I’m assuming because I don’t know for sure, but there is speculation that the scale may be bad. As of right now I am up and running and it feels good!