Post by bluejay27 on Sept 5, 2015 21:07:03 GMT -5
I had just moved my cnc router from upstairs to a more accessible location (so I'd use it more often) and on turning it on, the z-axis began to move on its own. Trying the controls, I could move the other two axes fine but only reverse the direction of the z-axis stuttering. Thinking I had a loose connection or broken wire somewhere from moving it, I started at the stepper motor and proceeded to chase after the problem. The stepper motor can't control itself, so it and the wiring to it were ruled out immediately. To check the driver, I first disconnected all three control wires just to prove I had the right one. I then disconnected only the step wire at the driver and no longer had any motion in the z-axis. This indicated that the step signal was being received by the driver and processed, rather than it getting an erroneous signal within itself (i.e. a short somewhere). I also tried disconnecting the step wire at the breakout board to ensure the 3 wire cable wasn't shorted (I just had this happen on a 2006 Chevy Equinox, 60 ohms between CKP signal and ground through the wire insulation!).
With no motion with the wire disconnected, the breakout board had to be either generating or receiving a bad signal. As I wanted to avoid diagnosing problems on the board, I opted to test for a bad signal to the breakout board. I unhooked printer port 1 and used port 2 and the supplied internal cable to test the cable and connector on the WD-1. Because I also had to unhook the external printer cable, I could not isolate the effect of each when I noted some variation in how the stepper motor shuttered. Moving the internal connections had no effect, but moving the external connection at the WD-1 did, although it never fixed it. Finally, I looked at my relic of a computer, disconnected the cable there, and cleaned up the connections (Nintendo style, although with shop air). After reconnecting everything, I'm happy to report that I do not need a new breakout board. But I am ordering a new printer cable in case I have future problems and need the spare for testing (note: I'll try it once to check for out of the box issues, you never know these days).
I'm sharing this because upon first discovering the issue, I was lost regarding where to look. For problems in which one of the electronic components were at fault, I would have been limited in what I could check or verify, as I might have opted to buy a new printer cable or somehow accessed the signal from the computer before condemning the breakout board. If this appeared to be the issue, an oscilloscope might be a worthwhile purchase. But knowing the effect it can have, for any future noise related problems, I will start by checking the printer connection.
With no motion with the wire disconnected, the breakout board had to be either generating or receiving a bad signal. As I wanted to avoid diagnosing problems on the board, I opted to test for a bad signal to the breakout board. I unhooked printer port 1 and used port 2 and the supplied internal cable to test the cable and connector on the WD-1. Because I also had to unhook the external printer cable, I could not isolate the effect of each when I noted some variation in how the stepper motor shuttered. Moving the internal connections had no effect, but moving the external connection at the WD-1 did, although it never fixed it. Finally, I looked at my relic of a computer, disconnected the cable there, and cleaned up the connections (Nintendo style, although with shop air). After reconnecting everything, I'm happy to report that I do not need a new breakout board. But I am ordering a new printer cable in case I have future problems and need the spare for testing (note: I'll try it once to check for out of the box issues, you never know these days).
I'm sharing this because upon first discovering the issue, I was lost regarding where to look. For problems in which one of the electronic components were at fault, I would have been limited in what I could check or verify, as I might have opted to buy a new printer cable or somehow accessed the signal from the computer before condemning the breakout board. If this appeared to be the issue, an oscilloscope might be a worthwhile purchase. But knowing the effect it can have, for any future noise related problems, I will start by checking the printer connection.
