Denford Software & Machines

Hi not been on here for a while due to the Triac being unused for a bout a year.
Yesterday I fired it up just to give it a run as I plan to machine up some parts in the next couple of weeks.
However I am having aproblem with the Z axis, it will only move in the + direction (ie up) whichever way you try & move it + or -.
Any ideas? I have eliminated the SD3 stepper card as I have swapped it with a spare I have and the problem persists.
I have also eliminated all of my electronics prior to the stepper card. Ie, breakout board, & interface board.
Could it be the motor itself?

Cheers, Roy

check with a voltmeter that the direction pin on the z axis is changing state. I guess you've already done this, but it's the most obvious place to start.

Thanks. No Havent actually tried that one. Whereabouts should I be doing this. On the drive card?
Sorry but I am trying to get my head around it all again as its a couple of years since I played with the Triac electrics.
Cheers, Roy

you can measure it at the end of the parallel lead where it joins the breakout board, or from the output of the breakout board to the stepper drive board. It's normally pin 7 or 6 of the parallel port. Pins 18 - 25 are ground.

Thanks, I'll have a look at that one then. Although I assume this will be ok as I swapped the X axis output (which I know is working) from my interface board to the Z to eliminate the breakout board & the interface board. hence I have a suspicition it is beyond this.

Cheers, Roy

knowing the wiring in the old green triac, it could well be wiring from the steppers to the stepper.

It could be condensation in the Z axis motor.

Iv'e given the stepper motor a good 'warm' 2 hours with the hair dryer, so I think thats eliminated any possible condensation. Still no Joy!
I will try and check the wiring from the stepper drives to the motors tommorow if possible. Only trouble is access being a pain!!!

it's not the easiest triac to work on. Check the plug in the column as well as the drive bay.
I still think the problem is a failed or loose Z axis direction signal.
Try changing the x axis to the z axis in ports and pins, eg 2/3 on the z to 6/7 on the x and see if the problem transfers to the x axis.

been at it with a multimeter today. All wiring from the drives to the steppers seems to be good.
I've been playing around with the outputs on the interface board (between breakout board & drive board). using the Z output I can replicate the problem on the X axis but still get the problem if I use the X output on the Z axis. All very odd! This leads me to beleive there is a strange undetected problem on the interface board. I had already installed a new transistor to no avail. (a problem item once before I recall).
Anyway just got back with all the components to build a new interface board, so that's where I am heading next.
Fingers crossed!

what breakout board are you using, and how are you driving the 12v logic on the sd3

Its a CNC4PC c11 breakout board into a homemade digiplan interface using 3K3 resistors & BC547 transistors (as per the digiplan manual).
Its this interface board which is the one I am going to re-make tomorrow. I remember a couple of years back I had a transistor go down on it causing some issues.
I think this is where the problem lies, I probably overcooked some of the transistors & resistors when soldering the board back then.
I am now armed with a more reliable and temperature controlable soldering iron!


If you see this post: viewtopic.php?f=14&t=1780
you will see my boards on trial from my conversion a few years ago.

you could run a wire directly from the parallel port pin to the 3k3 resistor on the base of the bc547, this will bypass the breakout board if you think it may be suspect. What you may be experiencing is the breakout board not getting a strong enough logic high signal from the parallel port.

Thanks Angeltech, I will knock up the new interface board tomorrow & give that a try. If I get no joy, I will run a wire as you suggest. I may have the experimental parrallel cable knocking about somewhere which I originally wired into the interface when I was first experimenting with the conversion before buying the breakout board.

some breakout boards have limiting resistors on the inputs of the isolators, you could try bypassing the resistors if they're there.

Well we are cooking on gas again tonight. Made up the new interface board, fitted it and she was away once more.
Strange thing is I can not find anything amiss with the old board!!
Thanks for your input anyhow.

Cheers, Roy

glad to see you got it going