Monday, 5 July 2010

TechZone Extruder Controller Testing

I have spent some time time trying to get the extruder board up and running. I hit a few snags along the way, and thought I would document them in case it helps anyone else.

Firstly is uploading the firmware, as with the motherboard you can use jumpers if you are unsure of your 10 pin cable, just make sure you get them correctly aligned, they are the opposite way round to the mother board so you have to put the extruder board on its back if you want to do it this way. First problem I had was getting the arduino software to correctly upload the firmware I was starting to think there might be a problem with the board. After a bit of looking on the Internet I saw many comments about pressing the reset button just before upload, I tried this and after a few attempts it worked! I was amazed. What I had to do was hold the reset button down, click upload, wait for the text to appear then let go of the reset.

The next was the wiring, i was baffled at first by how to set it up, there wasn't many clear instructions, but I did stumble upon the "official" guide which is hard to find (here is the link). On this site it shows a picture of how it is wired up. I copied the wiring and got some action when I tried starting the RepRap software, except to start with I was getting zero readings on the temp. It took a few attempts to get everything working, I'm not sure what I changed but it seemed like the boards needed to be started in the correct order, and having good solid wiring certainly helps, I've started using some premade jumper cables rather than the IDC connectors.

The extruder stepper now steps when i click extrude, and the thermistor is reporting the correct temperature. The only annoying problem is that the stepper makes a high pitch whine whenever it is not stepping, I tried trimming the pot down and it didn't help, just stopped the stepper from turning. I tried switching to the software PWM set current bypassing the pot but it didn't help either. I've been tracking the temperature and the stepper isn't getting hot so I'm not worried, but the noise is annoying. See below for a video of the setup printing the minimug.


  1. i've got the exact same config (zapp & tech zone), got the thing built, the axes work, yet the A3949 chips on my extruder board(s) keep catching on fire! it'd be really helpful to know how you are using zapp motors yet not overheating. lambert @ tech zone warned that the board couldn't handle the 7+ amperage of those motors as the A3949 chips are only rated for 2? no need the post this comment, so feel free to delete it. may i dialog with you more directly? thanks.

  2. Hi geeksautonomous thank you for reading my blog, are you sure you are using the same motors I am? I had a look on the datasheet for the SY42STH47-1206A steppers and it says the rated current is just 1.2 Amps.

  3. oh, using instead. rated 1.68. here's spec sheet: still, lambert claims the 12 volts raises the amps significantly. anyways, i'm stuck. any ideas?

  4. This might seem obvious but I assume you have used the pot to trim down the amps? I turned mine all the way down (anticlockwise) then slowly clockwise until I just got movement on the stepper. I have only run the motors for short periods of time - maybe i will have this problem in the future, how long did the chips take to overheat? Was the motor hot to touch? - I still doubt the 7 amp figure, I think my power supply would give up at 5 anyway, but maybe I am wrong, anybody else got ideas for geeksautonomous?

  5. going to try the kysan 1123029's which seem under 2A and makerbot uses and sells. not sure why the SY42STH47-1684B's are listed on the reprap wiki at all given the amp problem. plus, i can't seem to find anybody using them. lambert explains that, unlike the extruder, the axes boards do have a current sensing resistor on them so won't be as quick to overheat... though may eventually.