[WoodSpinner]

Hi,
I built my diycnc using a 4 axis hobbycnc pro chopper board. I have only been using 3 of the axis, so far and lately I've had problems losing position on the y axis, checked everything mechanical repeatedly even to tearing it down and reposition the mounts to give a smooth glide to the acme screw when turned by hand. No improvement.

I've been running it a little lower than the 3 amps my motors are rated for and they haven't run too hot, to give it a try I turned it up to the full 3 amps and ran the machine through its paces a bit without any real improvement.

When checking the motors to see how hot they are getting I found that the motor on the Y axis is staying cool while the other two are getting pretty hot. I rechecked the vref and its still set to 3 amps(.42vref). I intend to try the motor on my unused A axis but are there any other tests I should perform on the motor/driver to find the reason its like that?

Any and all suggestions welcome.

John

[H500]

Edited for correct speeling? =)

Try turning the powered motors by hand. Do the Y feel weaker than the others?

Swap the x and y motors. Do the problem follow the motor or the driver?

[WoodSpinner]

The Y did feel weaker, and swapped it with the z and it followed the driver so I .ooked my y motor to my "a" driver and it appears to have fixed the problem for now.

Guess I need to start thinking of replacing the driver chip on my Y axis driver...or just start saving for a g540.

Thanks for the response.

John

[H500]

Check the current sensing resistor for any signs of heat damage. Or just take a chance and replace it. I don't think the chip is the problem.

[WoodSpinner]

Thanks, which one would that be?

John

[H500]

Probably R9. Do you have a clear photo?

[WoodSpinner]

I dont have one of mine, but here is a close up from hcnc's webpage.
The problem axis is Y, so would that be R10?

John

[H500]

Yes. But if you don't see clear discoloration, then the resistor is not burnt. What chip are they using? SLA7078M?

Check J4 on each axis. Are they set the same?

[WoodSpinner]

Yes. But if you don't see clear discoloration, then the resistor is not burnt. What chip are they using? SLA7078M?

Check J4 on each axis. Are they set the same?

Sorry, I've had a busy couple days. The resistor looks fine, no signs of burning or overheat. The chips are SLA7078MR s.

All my J4 jumpers are in place, I've never used the current reduction feature. Altho I was wondering if it somehow was stuck in that mode given it did have about half power, instead of failing completely.


John

[H500]

Try removing and reinstalling the jumpers. Perhaps its a bad connection.