Hi everyone.
I have a 1993 Fadal VMC40.
About a year ago my way cover rubber was torn. Coolant got into the X axis motor and destroyed my bearings.
I took the motor out and put new bearings into it. I borked the tachogenerator and I didn't know what I was doing at the time so I bought another Glentek GM4050. I have been running this one ever since. Let's call the original motor, MOTORONE and this new one MOTORTWO.
Fast forward to now. MOTORTWO has been running great ever since. No misses, no quirks, great.
I had an order for 20 pieces, I made 18 and then I went on vacation for a week. When I came back, I turned on the machine, I was already at my CS marks, so I typed CS [enter] and the machine ran away towards X positive until it alarmed out.
I was stunned. This is definitely not what had happened ever before.
So... let's get into it:
THE Y AXIS WORKS FINE.
THE Z AXIS WORKS FINE.
I had since ordered a new tachogenerator and swapped it onto MOTORONE. I just assumed MOTORTWO had gone bad.
I wired up MOTORONE, now with new tachogenerator, and I had some runaway issues.
The X axis is slowly moving in one direction. Since I changed brushes and what not I tweaked the SIG on the X axis encoder board until the motor stopped moving. I could not CS though, because the motor still ran away.
I am drifting about .001 every 5 seconds.
Here's what is very weird though. If I set the increments to tenths, and spin the wheel, the x moves progressively faster. Like the handwheel is a measure of velocity.
The X drifts slowly at low values, but if I turn the value up or down the X moves faster.
Does that make sense?
The x drifts really slowly at .001, but the x drifts even faster at .250, as if the handwheel is controlling the velocity of the X axis. It never stops drifting. If I crank it up too far it alarms out.
The Y and Z work fine. One rotate click, one movement.
When it alarms out, the X still drifts as if it's seeing residual voltage, even before I hit manual and jog to reset the servos. After playing with the SIG potentiometer I can get the X axis motor to stay stationary, but if I move x one tenth to the negative it will continue to drift until I bring it back to zero, and then it stops again. If I move one tenth positive it will drift until I bring it back to zero, but unlike moving negative it will continue to drift.
I swapped the wires (the white and black and 2, 3, 4, 5, and 6) to the amplifier between X and Y and the problem stayed on the motor side.
Then I swapped the coax wires between the 1040 X and Y boards and the problem stayed on the motor side even though I was now controlling it through the Y selector on the front of the machine.
Well, that means motor, right?
So I swapped back to MOTORONE with its tachogenerator and the motor still runs away.
So what are the constants? I'm still using the same X axis resolver through all of this. And the wiring.
I take apart the rotary A axis and put the A axis resolver onto the X axis motor. It still runs away, and it's still a velocity generator like it's not getting a signal to stop moving.
I then take the Fluke meter and put a probe on the motor side and one inside the case. With the help of a friend we probed the wires one by one and jiggled the harness measuring for a resistance drop. There was no resistance drop.
So I've tested the harness as best I can.
I've swapped the 1010-4 boards.
I've swapped amplifiers.
I've swapped motors.
I've swapped resolvers.
I've swapped tachogenerators.
Here's where things get even more stupid.
I was flipping through my blue binder and it says
SLOT 9 is X axis 1010 board
SLOT 10 is Y axis 1010 board
SLOT 11 is Z axis 1010 board
SLOT 12 is B axis 1010 board
SLOT 13 is A axis 1010 board
SLOT 14 is Spindle
The card in slot 9 has a sticker on it that reads X AXIS and has jumpers 5-12, 7-10, 8-9, as the manual says it should.
The card in slot 10 has a sticker on it that reads Z AXIS and has jumpers 5-12, 6-11, and 8-9.
The card in slot 11 has a sticker on it that reads Y AXIS and has only one jumper, 8-9
I'm at a loss.