Hello,
I have just finished building the K8200 two days ago.
I now have the problem that I am not able to set the stepper motor driver reference voltage to 0.425V as described in the manual.
The problem is that if I measure 0V and then turn the trim potentiometer very carefully, the voltage at some point immediately jumps up to over 2 volts. I have tried to turn the potentiometer VERY carefully several times, but it was not possible to adjust the value to anything close to 0.4 or 0.5 volts.
I find particularly weird that this behaviour is the same on all four pololus.
I wonder if someone already had similar problems and may tell me what I am doing wrong ( I suppose that it is not a defect of the pololus, since all four of them behave the same way).
Regards
Did you try to adjust the drivers with all motors disconnected?
Sounds like there is something wrong with the motor wiring.
Thanks for your reply.
I disconnected all four motors and tried again to adjust the voltage, but the result ist the same.
There is no way to set the voltage to any specific value, because it jumps from 0V immediately to around 1.2V or more.
Try to measure the input voltage to the steppers.
It should be near 5V
Since I still have had no success and Velleman doesn’t seem to respond either, I took a closer look at the controller board.
I found that the voltage regulator IC (a 7805ABD2T 5V regulator mounted directly above the blue screw connector) got extremely hot already about 15 seconds after connecting the power supply, and with no load at all connected to the board. I am now wondering whether this is normal or if this indicates a defective part that might be responsible for the problems I have.
Edit: I just measured the output voltage of the 7805, and found out it was 0V. I suppose its time to return that board
Really NOTHING else connected? ( no heaters, motors, fan …)
Shure you didn’t attach the power supply with reversed polarityß?
The power supply is connected as shown in the manual.
I disconnected all connectors from the board, and still the voltage regulator behaves as described above, it gets very hot only seconds after plugging the power supply in and its output voltage is 0V.
Measure again after pulling all motor driver boards out.
Maybe one of them is faulty.
Thanks for your ideas and suggestions.
I just tried that out as well, but unfortunately, things did not change.
Well, if there is no reverse polarity on power input and no solder shorts on the board backside (check that)
you should get a new mainboard. Ask Velleman for replacement.