X Axis Limit Switch ok, but Doesn't Stop

[Friken]

Replicator Dual:

When going to home position (back right), the x-axis limit switch led lights up when hit but the stepper motor grinds for another 10-15 seconds as it tries to continue. In troubleshooting this, I swapped limit switches and new switch does the same. The LED turns on as expected. Not in manual job mode I discovered something interesting. If Y axis is around center, then the X limit switch works fine. If the Y axis is within 25% of the back of the machine then the X limit switch seems to be ignored. I'm on 7.5 firmware.

The machine worked fine for ~40 hours before this started happening. The grinding is terrible and I imagine it will break itself if I just continue using it with this issue. Any ideas?

Thanks!

Aaron

[Friken]

type fix:
"Note in manual job mode I discovered something interesting."

[Jetguy]

Just because the switch lights, that means the switch works and says nothing about the actual sense wire of the 4 wires in the cable.

Inside that cable is sense, GND, GND, 5V. For the light to work you only need a ground and 5V but that doesn't man anything to the board.

Given the shear number of cable failures it's a safe bet it's YET AGAIN the cable.

This is the part that gripes me, I can tell what wrong with your bot across the internet in one post. Why is it that the troubleshooting guide in the help section cannot properly help users to diagnose this?

[Dan Newman]

On 30/01/2014, 1:09 PM, Friken wrote:
> Replicator Dual:
>
> When going to home position (back right), the x-axis limit switch led
> lights up when hit but the stepper motor grinds for another 10-15 seconds
> as it tries to continue. In troubleshooting this, I swapped limit switches
> and new switch does the same. The LED turns on as expected. Not in manual
> job mode I discovered something interesting. If Y axis is around center,
> then the X limit switch works fine. If the Y axis is within 25% of the back
> of the machine then the X limit switch seems to be ignored. I'm on 7.5
> firmware.

You're wiring is shorting somehow. The red LED going on is a "local" event
to the PCB. It is not controlled by the motherboard. So, just because
the LED lights does not mean that the motherboard is receiving the signal
which tells it that the switch has closed.

> The machine worked fine for ~40 hours before this started happening. The
> grinding is terrible and I imagine it will break itself if I just continue
> using it with this issue. Any ideas?

Contact MBI and get a new wiring harness.

Dan

[Friken]

I think that is the problem. I was able to further troublshoot it in manual job mode. Pulling/bending the wire that bundle that goes to the limit switch I could make it stop/start working correctly. Must be a broken wire in there :( Fun fun...

[Bryon Miller]

This happened to me twice already.  It was the wiring harness.  You have to contact MBI, they'll probably send you one for free since it failed after only 40 hours.  My first one lasted almost 1500 hours, my second one lasted 5 days, they sent a 3rd one for free.  You will receive a wiring harness in a ziplock bag with absolutely no instructions whatsoever.  It will have the harness and an additional wire with no markings at all.  This additional wire is a high flex cable.  When I installed this harness for the 3rd time, I avoided routing it up the case through the zip tie that the end stop cable is going through as well.  I doubled the wire ontop of itself to deal with all the slack, tucked it under the clips on the case and used packaging tape to hold the cable to the floor of the printer.  Then plugged the flex cable into the connector for x.  This way the wiring harness itself remains stationary at all times and if there is any damage, it will only effect the flex cable and you won't have to take the machine completely apart to replace that harness again.

There's a short in your wire and it is not letting the firmware know that you are hitting the switch even though the light turns on.  I think Jetguy was who explained this to me....  Replaced the harness just like he said and it worked perfect again.

[Jay]

Had this on my R2...it IS the cable..I had dropped mine when I replaced them (the SECOND time)...so I shouldn't have been bending the poo out of it..but..it failed just like yours. I fixed mine by using a small square of tape to keep it straight as it enters the side carriage....hasn't happened again and that was couple of months ago..

Cheers!

Jay