Greetings All!
I recently acquired second hand a Nomad 3 from ~2021, which ended up having an intermittent z-axis proximity switch. My repair may be of some value to the knowledge base as I found support not very forthcoming with board/assembly level information, preferring to recommend that I either replace the switch or the controller PCB out right. My insistence for info prompted them to eventually point me towards this thread and to confirm that they are using the Micro-Fit line from Molex on their proximity switch assemblies.
Fault: Upon power up, N3 would successfully initialize and home. After performing spindle warm up, the Z-axis proximity switch failed to detect the carriage during a subsequent homing operation. This resulted in a stalled motor, loud noise, and eventually software error and shutdown. I found this failure to be consistent over the next 24 hours - After being switched off for some hours, the sensor was found functional again, but would eventually stop working.
Troubleshooting: Mostly observing that the sensor would and then would not detect a screwdriver when powered on. Powered off, I removed the the back panel, then power input side panel, and control enclosure to gain access to the control board. Disconnected, I cut the z-axis sensor cable at the board to simply pulling attached cable through the wire chain. Once removed, I performed a rudimentary bench test on the sensor with a bench supply and multimeter. ~6v was connected across Brown(+) and Blue(-) wires. Voltage was measured between Black and Blue wires. Black measures HIGH and sensor would not switch LOW when metal was placed in near sensor. LED would remain off.
I found a similar looking sensor on Amazon - a knock off TL-W5MC1 (NPN). Tested functional per above procedure. LED would turn on when metal was placed near sensor. Multimeter indicates a transition from HIGH to LOW (~0V).
Replacement sensor installed and cable routed back through wire chain. Wires stripped and crimped with header sockets already on hand, and then hand pinned contacts at PCB connector. Intermittency no longer observed.
Repair:
Comimark 3Pcs TL-W5MC1 Proximity Sensor
*warning: The label attached to these indicate incorrect polarity.
Molex Micro-Fit Receptacle Housing, Dual Row, 8 Circuits, Black
Molex Micro-Fit Crimpt Terminal, Female, 24-20AWG
iCrimp IWS-3220M Micro Connector Pin Crimping tool
I used a crimping tool I had on hand made for similar style contacts. I have no doubt that one more appropriate to this contact type is out there, but as Tyler felt necessary to warn me at the end of this, “Molex tools required to work them can be a bit on the expensive side.” Connectors are stocked at any number of online retailers, but I opted to request that Molex send me free samples and joyfully received a connector and 5 contacts next day. Before I was given the actual connector type, I found a similar one offered through TE.
Micro MATE-N-LOK, 8 position, 2 row, crimp, receptacle
Still waiting on that one to come in, so I’ll be sure to follow up and let y’all know if it’s in any way compatible.
I hope someone finds this helpful. Thanks!