Connectors for Y endstops.

Hi, I’ve had my mini for about 1 1/2 years and it’s worked great. But recently, the back Y endstop doesn’t engage and the mini will often try to force the plate off the back of the rail when homing. I replaced the back Y endstop switch, but it didn’t fix the issue. So tonight, in desperation, I took the cover off electrical compartment and looked at the mini-rambo board PDF off the lulzbot development page.

Using a multimeter I’ve been able to isolate the issue to either a break in the switch wire or on issue with the wire connector housing on the rambo side. I know because if I check the connectivity of the red wire my multimeter beeps but I can’t get a reliable beep on the black wire. Sometimes if I twist the wipe etc, I get the beep.

To make a long story short, I want to replace the connectors on both ends of the Y endstop wires(both rambo and switch side). The PDF calls for a 4ucon 02005 on the rambo side. I can’t find this part or the wire housing on digikey, so I was hoping someone might be able to give me a housing part number from either digikey or mouser. A part number for the connectors on the switch side would be great as well.

Thanks in advance and if this isn’t the correct place to ask a question like this let me know and I’ll try lulzbot technical support tomorrow. But since the printer is not under warantee I’m not so sure I’m going to get much help from them.

For the switch side, you will need a 2.8mm Crimp Terminal female spade connector. Ebay has them, they are fairly difficult to locate I have found. I don’t know if Digikey has them . For the Rambo side, assuming the Mini rambo uses the same connectors as the full size ones, this one should work and then the pins for it are here: The Full size rambo uses a 3 pin connector with two of the pins occupied. You’ll want to double check that against the mini one. The 4 pin ones are here:

You probably have a broken wire, so you might just replace that wire - connectors and all.

Thanks, that’s the information I needed. And yes, I’m planning to replace the wires since the wires will probably be too short if I cut off the connectors.

I was about to throw out the mini, but with the cost and the openness of the hardware I would hate to do that over a few dollars worth of parts.

Even a broken mini still has a significant amount of value in it. you probably would want to sell it rather than throw it out,

I’ll start the bidding at $5.

Do I hear $10?

I’ll trade a pile of obsolete taz 3 parts for it heh.

Seriously, I have basically an entire printers worth of those.

With the information from piercet, I was able to replace the endstop switch wires and connectors on both end. My mini is now functional again, and it no longer tries to push the plate past the endstop!!!

I was able to find the switch side connectors on digikey if anybody else hits the same issue. Or I mean an almost identical clone from TE connectivity.

I do have one more issue. I think the same issue is happening with the bed temperature sensor wire. Either the connectors or wire is breaking. If I watch the bed temperature in printrun, I sometimes see glitches where the bed temperature will drop to 0 for a few moments, then recover back to the correct value.

So my question is if it’s safe to use the printer in this form? If the bed temperature sensor wire completely breaks and the rambo thinks the bed plate is 0 degrees for a very long period of time, can the heater get turned on long enough to cause property damage, personal injury, etc? Perhaps the marlin firmware should be modified to shutdown at least the bed header if the temperature is stuck at 0 degress for a long time?

I plan to swap out the temperature sensor wire really soon, I just don’t want to take the time to do it right now. I do think the cause of this issue is that after a long period of stress of the plate constantly rocking back and forth, the wires and connectors are developing small cracks which lead to an unreliable connection.