One tower moving down but not up

[bnk]

Hello, my name is Bodie. Been printing for about 8 months. Have stayed off the boards to not waste folks time and figure it out for myself, but I am stumped. I've done repeated searches on the boards, Youtube, etc. Rostock Max V2, Arduino 1.6.6(downloaded from Gene's manual, but latest version), Matter Control 1.4.0. Z tower is moving down but not up, cannot Home All to recalibrate. I have tested all electrical circuits, to the best of my ability (not an electrician, it's not my strong suit, but I know enough to see a complete circuit). There is power all the way through the circuit. If Z is moving in one direction, there must be a complete circuit. Have had issues with the end stop Z plug (the plug was a loose fit into the Rambo, so I shimmed it to make contact), so that was what I went to first, but again, there has to be a complete circuit or Z wouldn't move at all. So one direction means it must be somewhere in the software, unless I am mistaken (likely possibility I have reinstalled MC, Arduino, cleared and reflashed the EEPROM, redone everything all the way to calibration, but can't calibrate, with no up (again, it only moves down) on the Z tower. Any help GREATLY appreciated.

[Eaglezsoar]

One of the first things I would try would be to turn off all power and unplug the z axis connector and the y axis connector. Plug the z into the y connector then power up
and load your software and move only the y axis, does the now z axis move in both directions? That is the basic troubleshooting mindset to figure these out. If Z does not
move in both directions after plugging into the y connector, then that indicates a wiring problem or a defective stepper on Z. DO NOT EVER PULL OR INSERT A CONNECTOR ON THE RAMBO
WITHOUT FIRST TURNING OFF THE POWER!

[bnk]

Got a Z_max:H, on M119, so gotta be a wiring/connection issue, IMO. Sorry to waste anyone's time, but thoughts are greatly appreciated. This is a brand new Rambo, so I don't think the disconnect is there.

[Eaglezsoar]

Got a Z_max:H, on M119, so gotta be a wiring/connection issue, IMO. Sorry to waste anyone's time, but thoughts are greatly appreciated. This is a brand new Rambo, so I don't think the disconnect is there.

Don't feel that you wasted our time, this forum exists to help EVERYONE with their questions.
If you still don't figure it out leave us another message.

[bnk]

TYSVM! Plugged Z into Y, moved the Y using MC, same thing, down but not up. Had not thought of testing in that way, so thanks again. Now I can visually see that the other two arms are NOT dragging the Z cheapskate, so that was a misdiagnosis. Gotta be in the plug, I think. Showing a Zmax:H, of course, but also a Ymax:H (after removing the Z plug, not sure if I made that clear). Will resolder the plug and see what that does. Have had bad static here lately, I hope that the board is OK. Sheesh, this should not be this hard...

[bnk]

Board has to be OK, I think or it wouldn't do the same behaviour with the Z plugged into the Y. One step closer...

[bnk]

Unless it's the stepper, but it doesn't make sense that it would fail only in one direction.

[Eaglezsoar]

Unless it's the stepper, but it doesn't make sense that it would fail only in one direction.

Sure it does, there is a pair of windings inside the motor. if one pair is open or not correctly connected then the motor can only turn in one direction.

[bnk]

Makes sense. But would a stepper motor fail this early? Of course anything mechanical can fail at any time, but it seems a little early for medium-light usage (8 months). Those things look and feel like they're built like tanks. And the zmax:H when I am plugged into the Z end stop plug or the Y end stop plug (Ymax:H with the M119 command) would a bad stepper do that? I thought that was just showing a closed connection to the limit switch. Still chuggin' away here, had to take a break last night from this blessed/infernal machine.

[Xenocrates]

if it's got a tripped limit, then I would replace the limit. but first, unplug it, and see if it will rise with the limit unplugged (I wouldn't home it, as it would require you to kill power, but say, a 10MM lift would tell you if it was now working) Little switches like that die all the time. I've had some where they would bend the leaf enough it no longer contacted the actual switch, some where the leaf was pulling loose, some where the spring died, some where you had to shim them with paper, some where the little sprung switch would buckle sideways and get stuck in the casing, and some where the contacts would just fail. Of course, these were used for little robotics fixtures for students to use (including me, I'm no teacher.) But the thing is, out of about 60 limits installed in those fixtures, all of those failure modes were either present and compensated for, or came up over a 15 week semester. some of them were reliable, and some would fail almost instantly. Get a few new ones as spares, is basically what I'm saying.

Once the limit is replaced, any further symptoms are either the stepper themselves, or the wiring harness (unless you somehow ended up with a bridge on the rambo somewhere)

[bnk]

Got it, it was a disconnect at the Z stop connector on the Rambo. Very gently tweaked the second pin on the third plug, got an L on the Z tower with M119 command. I am headed into complete recalibration, but IT'S RUNNING! Thanks to all for the help. Thank you Eagle and Xeno, you have moved me forward in this journey. Punched the wall once, though. No broken knuckles, so all is well. Just kidding around, but did punch the wall, however it was a soft punch. ;-P Frick on a Stick.

[Eaglezsoar]

Great job bnk! your trouble shooting skills will only improve as time advances but I am glad that you got it working.
I am 64 and learned a long time ago that the attitude of I can works a lot better than becoming frustrated.
Again, great job!