Centroid M39 only moves in one direction ... all axis ...

[pabut]

Hi all .... I've volunteered to help a local Tech School get their CNC mill working.

Mill is a Bridgeport (model/specs escape me) with an OLD Centroid M-39 controller running CNC7

Got a problem where the table and the head only more in one direction, the negative direction (-) no matter what you tell it to do ... i.e.: push the X+ button on the JOG pendant it moves to the X- direction .... same for Y and Z ... all three axis behave the same. If I keep pressing the button motion will continue to move till it hits the minus limit switch.

We've checked all the connections ..... confirmed the limit switches work .... only oddity .. and not sure about this ... red LEDs on the servo controller are ON when the label says "normally off" yet they blink when the servos are moving.

This just seems like something BASIC that is either not working or set right ... Any help appreciated!!!

--> Rob

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[cncsnw]

What messages appear in the message box when you are pressing minus or plus jog buttons and it is moving minus?

If you select INCRemental jog, SLOW, x100, and press an axis jog button once, does the axis move slowly (minus) just 0.010" and stop? Or does it abruptly run away several inches, then report "... position error" or "... full power without motion" in the message box?

What is your CNC7 software version?

[pabut]

I'll need to get back into the shop to try the incremental jog ... and the actual software version .... I have seen both the "position error" messages and the "full power without motion" motion message ... don't remember what specific actions brought up each message. One other tidbit I didn't mention ... when I first turn on the machine it wants to be homed .... I hit ALT-S (cycle start) and it jumps for about a half second in the negative direction on all three axis and then a "position error" (z axis I believe) pops up.

Thanks!

--> Rob

[cncsnw]

Several possibilities here:
1) You could have a failed servo amplifier (FETs shorted through). However, it is unlikely you would develop a problem like that simultaneously on all three axes.
2) You could have a faulty servo drive power supply. If I recall correctly, loss of either the +12V or -12V level from the power supply to the drive board throws the analog current regulator off.
3) You could have lost encoder feedback. Again, this is unlikely to have happened on all three axes at once unless someone disconnected all the encoder cables, then reconnected them in the wrong places.
4) You could have the servo motor power wired backwards. Again, this would require active intervention: someone disconnecting them, then connecting them back with the wrong polarity.

You can check the encoder feedback on the PID configuration screen: F1/Setup -> F3/Config -> "137" -> F4/PID. Leave E-stop pressed in and turn the servo motors or screws by hand. You should see numbers counting in the "Abs Pos" column for each axis as you move it. Verify that you get approximately 8000 counts per turn of the motor: plus going one direction, minus going the other direction. Also verify that the number is changing on the correct line (that the axis encoder connections aren't crossed).

Look at Centroid Servo Drives and figure out what type of servo drive logic power supply you have, and, if it is a Toko, whether it has plug connections or soldered connections. Try cleaning all the connections as described on http://www.cncsnw.com/ServoLogicPM.htm . Check whether you are getting all three DC outputs from the logic power supply: +5VDC, +12VDC, -12VDC.

[pabut]

Good stuff ... first thing I'm going to check is those supply voltages .... that seems most likely. We looked at all of the connections from the PC encoder connections .... checked / reseated everything ... verified all going to the correct place .... also the fiber optic connections from the PC to the servo board and the PLC board ... we see status lights near the connectors change when we remove and insert the fibers.

I'll try to grab some screen shots of the errors next time I'm there.

Thanks for all the advice!

[countryguy]

Just wondering if you fixed your rig? Something I've sort of noticed is that w/ these Centroid setups- The forum is usually only used when a critical issue or install issue arises. Nothing about goofy intermittent errors, or software bug fix number 3,840 for Version 3, or crazy behavior on this gcode cut or that.... It's a testament to the mature nature of the Software and the hardware and their ability to work together very well. I'm a fan so far.....can ya tell?

[pabut]

Just wondering if you fixed your rig? Something I've sort of noticed is that w/ these Centroid setups- The forum is usually only used when a critical issue or install issue arises. Nothing about goofy intermittent errors, or software bug fix number 3,840 for Version 3, or crazy behavior on this gcode cut or that.... It's a testament to the mature nature of the Software and the hardware and their ability to work together very well. I'm a fan so far.....can ya tell?

Thanks for replying! I haven't been able to get back to the shop yet .... been on the road ... hope to this week sometime.