Z Axis doesnt want to go down anymore

Hi Reprappers,

my reprap mendel is still in process but there is only the extruder missing. So when I try to move the axis manually from the PC everything works fine except the Z-Axis, when I want to move it down after moving it up. (also "home all" resets all axis besides Z-Axis)

When I want to move it down it doesnt do anything except crashing the reprap software on my pc, it doesent react anymore.
When I "home" all, then the z-Axis moves quite a litte bit, like it has already reached the opto endstop and the motor stops, but the endstop is still far away.

It cant be the steppermotor: When I switch the polarisation and move the z_axis with the software up, the axis move down properly.
I use the Generation 3 Electronics/Tech Zone Remix with nema 17 motors.

There must be something wrong with the electronics or with the firmware, but the strange thing is: 1 month before everything was fine and I didnt do anything with the reprap except letting him stand around, and now there is this problem.

Can anybody help me? Would be so kind! Thanks in advance! Tobias

edit:
everything works properly but when I want to lower the Z-Axis, there is a report in the log of the reprap-prog:

ERROR: GCodeWriter.waitForOK(): Serial Error: checksum mismatch [0,000s/-1284298
899231ms]
ERROR: Requested to resend line 280 [0,005s/5ms]
ERROR: Resent: N280 G1 Z0.4125 *100 [0,015s/10ms]

Edited 2 time(s). Last edit at 09/12/2010 09:53AM by crayzo.

Sounds like your Z min endstop is not working right.

Is there a led light on your endstops? Gen 3 electronics have a green led on the endstops when they are powered on and nothing is between the uprights. Might need to check the z axis endstop wiring or perhaps swap endstops to test. Good luck.

no, there is no problem with the endstop. I have one endstop missing at the y-Axis because it doesnt work. Then I plugged it off and then it was possible to "home" the axis, even if the motor stops a bit later then necessary, it workes. But not with the z-Axis when I do the same.

And yes, there is a green light at the andstop, when its turned on. And when I put sth. between the green light turns off, so actually everything works fine there.

Any other options and ideas? Im quite a litte bit depressed =(

thanks in advance! Tobias

Edited 1 time(s). Last edit at 09/08/2010 02:26PM by crayzo.

Perhaps the link between your endstop and the pin on the micro is broken somewhere.

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[www.hydraraptor.blogspot.com]

Unplug all endstops and you can be sure they aren't the culprit.

Then swap stepper drivers and stepper motors. Does the Z motor work on the X axis? Does the Z axis work if you use the stepper driver from the X axis? All motors ans stepper divers are exchangeable, so it's pretty easy to track down the faulty part.

Oh, and disassemble the Z motor to find out wether it's simply a matter of high friction in the mechanics. Stepper motors have pretty limited tourque.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Would it be possible, that the problem is caused by this Problem:


My RS485-Chip on the motherboard (gen3 techzone) one time was fallen down, beacause the tin solder didnt work properly? I solded it again, but im not sure if exactly properly.

But actually this chip is only for the extruder, right?

thanks in advance

edit:
everything works properly but when I want to lower the Z-Axis, there is a report in the log of the reprap-prog:

ERROR: GCodeWriter.waitForOK(): Serial Error: checksum mismatch [0,000s/-1284298
899231ms]
ERROR: Requested to resend line 280 [0,005s/5ms]
ERROR: Resent: N280 G1 Z0.4125 *100 [0,015s/10ms]

Edited 1 time(s). Last edit at 09/12/2010 09:47AM by crayzo.

No that chip would only affect communication with the extruder.

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[www.hydraraptor.blogspot.com]

I have the same problem. Please, does anyone know how to proceed?

Just for the record: Z cable from endstop to controller had bad signal (blue) connection. Everything works for me, now!