Need Help!- Siemens 610 axis drive fault

[Charles2]

My Siemens 610 axis drive (6SC6140 X-axis drive) faults out after about 15 seconds from power up. The 'T' test point on the 'N' board counts up to about 9.3 volts, then the drive faults out with the center LED on the 'N' board on. I can disconnect the DC bus and the motor leads from the power board (6SC6140 board), leaving only the ribbon cable, and it still faults out the same. I can swap with another 6SC6140 axis board and the problem moves with the suspect board. I need advice and or a component level schematic of the 6SC6140 board.

[gridley51]

What leds are lit on the N card and the GO card?
Mark.

[Charles2]

Thanks for responding Mark. On the N board, the center LED next to the 'T' test point is lit. It is called 'V2' and labeled 'Speed controller amplifier driven to maximum' in the Siemens 610 manual. On the G0 board, 'V4' (enabling), the top green LED, and 'V1' (fault), the bottom red LED are on. I tried a different G0 board and it faulted the same. I have 231 VDC on the DC buss. I checked the DC buss with my meter on AC to test for ripple and it displayed random values from 230 down to 0. My meter is True RMS.

Thanks, Charles

[gridley51]

The fault led on the GO board is on because you have a fault in the system.Because you have a fault the control disables the enable circuit thus bringing on the enable LED on the GO board.So you are down to deciding between the N card and the Stack (amplifier ) card.Swap the stack card to another motor.If the same leds are on the fault is in the N board if a different led on the N board lights the fault is in the stack card.
It won`t matter if your stack cards are different power ratings as long as you don`t try to run a motor,just power on to see where it faults.
Often there is a spare axis on the N card,in which case you can swap to that but it is a bit involved if you`re not sure about it.
Mark.

[Charles2]

When I switch amplifier cards (aka power board or stack card) the fault follows the suspect board to another set of LED's. Now I have exactly the same fault on another axis. I don't think it is related to switching cards because the new fault is on a card that was not switched. I need to know more about the fault sensing circuits. Something is causing these boards to fault out and I need to find the source before I damage more boards. Could the CNC control cause a false sensing circuit fault?

[gridley51]

The sensing circuits are in the 610.When they fault the GO board disables the drive ready signal to the control which then disables the enable signal from the control to the drive.
Is this a machine you have had running or something you have just bought?Are the piggy back boards on the N cards set correctly.What manuals do you have for the drive?Have you had servo motors off?Another thing is these controls don`t like dampness.If you have not had it powered up for a long time,it is better to stick a blow heater on them to make sure they are totally dry before powering up.I have a few of these on machines and I`ve only had a couple of GO board faults and one N card fault over the years.
Mark.

[Charles2]

Thank you again for responding Mark. This machine is a Cincinnati Milacron T20 horizontal mill with infinite B axis. It was surplused from a large company that had not run it often, but it had been run. When it was moved from their shop, it was partially disassembled (badly). Wires were cut leading to the Z and B axis'. It sat outside covered with tarps for at least a year. I have it now and have been working on it in spare time for a year and a half. I have cleaned, assembled, leveled, repaired cut wires, built a 20HP phase converter with voltage line to line within 5%, switched the built-in transformer from 460 to 230 volts, revived the Acramatic 950 control, switched the hydraulic pump motor to 230 volts, replaced spindle seals, tool changer seals, table seals, sorted out the DCDNC program loading. I ran the machine manualy, referenced all axis' and tool changer (many times), and ran short test programs in auto. Then the B axis started faulting out. I removed the B axis motor to see if the axis was too tight. It was not, but I dumped about a quart of water out of the B axis motor, cleaned and baked the motor dry. The motor lead connector box cover had been left off while the machine was stored outside. It ran for a while and started faulting again on B axis. I switched the B axis and Y axis power boards and the fault moved to the Y axis, so I was fairly sure the problem was in the B axis power board. I tried to test the board, but without proper board level drawings, I have not been successful. I found a spare 40 amp power board at a good price and replaced the B axis board, but by this time X axis had started faulting the same as B had done. While testing the X axis, B axis started faulting again. As for manuals, I have the Siemens manuals you were kind enough to send to my son several months ago, and the Cincinnati Milacron manuals that came with the machine. I have to say that CNCZONE has been a great help through all this. I have learned so much from you guys. Thank you for your interest and for your help.

[gridley51]

Charles,
first off,I have made a mistake with this earlier statement:-
"The fault led on the GO board is on because you have a fault in the system.Because you have a fault the control disables the enable circuit thus bringing on the enable LED on the GO board."
It should have said:-
"thus bringing on the fault LED on the GO board."
Did you phase out the motors you have had off?It`s not just a matter of swapping two phases,you have to go through all the possible combinations to find one where the motor will sit quiet,not runaway or generally not sound correct.This is sometimes easier done with the notor lying on the floor using temporary leads.
Even if the motor for some reason or another pulls max current the drive should trip but not be damaged if the dip switches on the piggy back boards on the N cards are set correctly.Check the settings against the motor number in the tables which are in the manuals.
Another thing to consider is both B and Z axis may have brakes on them.If so are these being energised when powering up the servo system?No power = brake on.
The dc buss voltage is not correct,it should be 210 volts dc.This would affect the bias voltage in the sensing circuits which I think are + - 18v.
Check the three phase power to the drive,it should be 165 ac volts between phases.
Bear in mind that I have found that the older dc drives of all makes after standing for a long time in not ideal conditions may start up ok but start faulting after a bit of use.
Sorry,I don`t have board level schematics.
Mark.