View Full Version : X, Y and Z are dead

09-10-2006, 12:38 PM
Well yesterday, after a major rework, I fired up the PRT. X and Y run back and forth O.K.
Z went up about 1" and stopped. Now knowthing works.
The control board has an LED that is lit up.
But none of the steppers will move. I tried rebooting everything but still knowthing.
Looks like the power supply?
Is it the power supply in the computer box that the board comes inside of that can be just switched around? Those power leads have 4 wires. They must feed more than 1 voltage amount. Maybe just part of the power is dead because the LED on the board and the front of the box is lit.
Please help.

09-10-2006, 02:15 PM
Do you have a voltmether handy. Check the power going into the power supply and then check the power coming out of the power supply. If something is going in, but nothing is coming out, then the power supply has a problem. If something is coming out, then you need to check further down the line (at the controller board, for instance) to see where the failure is. I don't have schematics for the PRT, so I can't tell you where to check. (I'm assuming that the Shopbot control program is working, but that the steppers are not resonding.)

09-10-2006, 04:23 PM
As far as the 4 wires go the yellow wire is 12v and powers the controller both blacks are ground, and the red is 5 volts to power other circuitry on the board. If the led lights then 5v is good. If software seems to work 12v is good. The motors themselves are powered by a separate power supply. Look at the Silver box at the front of the cabinet. That is the motor power supply. There should be a led that lights up right to the side where the wires connect. If it doesnít light up, then there is probably a short overloading it. The supply is protected well so turning everything off and waiting a bit should reset it, but if thatís the case you will have to eliminate the cause.

09-10-2006, 04:53 PM
Thanks Dirk, thats what I was looking for.
There is a 2 wire lead coming out of that silver box going to the controller board (was wondering what that was). I'll check the voltage there. Do you know what that should be?
And I guess I'll have to get the power supply from ShopBot?
I did check all the wiring, didn't see a short anywhere. Can a bad stepper take out the power supply vers just the output for the one driver?
Because I did do some wiring work inside the stepper to my second Z. I was not able to test the second Z before this problem turned up but it was plugged in to the harness. If power is going to a stepper continuously I guess if it is shorted it could cause problems when not running.

09-10-2006, 09:34 PM
The supply is 48 volts. It has an adjustment that adjust the voltage. It is usually turned down all the way to around 42 to 44 volts. I would unplug the wire going to the circuit board and test without anything hooked up. I thought I had blown the supply in mine at one point, but found after everything had cooled down the supply was ok. I did blow a driver from a loose connection going to the motor. Check the circuit board to see if you see any signs of burnt traces or components. The fact that you went into a stepper motor makes me suspect you may have a blown driver. If the power supply comes back to life I would unplug all motors except for 1 and try running it by plugging it into 1 motor connector at a time to see if a particular driver may not be working. You need to be sure you shutdown everything down in between each test. You want all power off before you plug or unplug a motor.

09-11-2006, 04:54 PM
Well I found the problem.
The output for the second Z is shorted.
It was not because I had one of the steppers apart. But that did point in the right direction.
The second Z came loose with the machine when I bought it. And when the previous owner updated from a PR to a PRT he never changed the wires on the second Z stepper. It seems the steppers are wired different. Some of you guys may know this but I didn't. When updating from a PR to a PRT the white wire from a stepper motor MUST be separated from the yellow wire.
I won't do that again.
ShopBot said they can repair the board.

Thanks for the help Dirk.

09-18-2006, 01:09 PM
Z axis stepper hums when given up or down signals but does not turn. I got it going once by moving the rotor out but that no longer helps. I can turn the motor freely when its not under power - bearings are fine. I'm thinking that a new motor is required. Might that be so? If yes, it would be better there were a little more power. Present motor is PK266-02A. If I bought a PK266-03A would I have to make changes somewhere? Where?

Thanks, Cochrane

Brady Watson
09-18-2006, 01:16 PM
Is this a PR or PRT?

If it's a PRT you can try running it on the accessory channel. Regardless of model, try turning off the control box, and unplug the Y motor, plug the Z in it's place. Turn control box back on and try moving the Y, which will now be the Z. If it moves, you have a bad Z driver, if not, then it is either the wiring or the motor.

Check the motor wiring BEFORE you switch out the Y & Z.