# Anet A2 3D printer suddenly will not home X and Y

I have been using my Anet A2 for about a year. A few problems but none that I haven't been able to resolve. Today it suddenly stopped auto homing.

Using the position commands I can advance the X and Y positively but not negatively (after I manually re-position the carriages before turning the printer on). Also the Y stepper motor makes an unusual noise and it will over advance the Y axis. This behavior was preceded by a feed fault. The print started fine but the stepper motor stopped feeding shortly after the print started.

I am printing from an SD card as I always have. I changed SD cards thinking it might be a connection problem and I checked the G-code and all the commands including the E commands seem to be there. I have checked all the electrical connections - they seem to be fine.

Any suggestions to solve this?

• Hi Peter, welcome to 3D Printing.SE! Bummer if it suddenly stops working like it used to. I've added an answer, but am clueless of the preceding feed fault that might have triggered it, I'm sure others will add answers to hep you find the problem! – 0scar Jul 6 '18 at 7:28

Please check connections to the Y stepper first. You could replace cable from 'X' axis to test the connection.

The noise from stepper mostly means a disconnected pin (broken connection), an obstacle on the path (check and clean if any) and a worse-case-scenario a broken stepper driver, so you could swap steppers (just by connecting the cable) to see where is the reason. If 'Y' stepper works fine when connected to another axis slot (excluding extruder ones) then driver need a replacement.

I have experienced this a few times, usually this is related to the end stops.

If your end stops are somehow triggered (e.g. short circuit or cable broken; depending on the setup), the steppers will not home (as they think they are at the limits already) and only advance forward. Please look into the end stops of X and Y. Use a multi-meter to measure them and trigger them manually.

Alternatively hook up your printer to your computer with a USB cable and download a printer utility/application that can interact with the printer (e.g. Pronterface, Repetier-host, OctoPrint, etc.) and go to the terminal interface and send the M119 instruction to see the status of the end stops.

• Could it be that the endstops are inverted? Open = endstop reached. As the web you linked M119 states, you can use M119 to invert them. It would make sense that you can go forward but never back, because an inverted un-clicked endstop would act as a clicked endstop. – Petar Petrov Jul 6 '18 at 8:58
• @PetarPetrov In the firmware configuration you define the end stop inversion, e.g. in Marlin Firmware #define X_MIN_ENDSTOP_INVERTING true. This doesn't suddenly change, this needs to be manually uploaded. The best guess is therefore that the end stops are shortened or broken (depending on the firmware settings, e.g for NC, Normally Closed, or NO, Normally Open), and should be checked. M119 is very handy in that respect as you see what is reported. – 0scar Jul 6 '18 at 9:07
• It doesn´t suddenly change, but a M119 can change it. In redeem, M119 can also be used to invert end stops. Example M119 X1 1 This will invert end stop X1 (Inverted means switch is connected in Normally Open state (NO))  – Petar Petrov Jul 6 '18 at 9:46
• @PetarPetrov Sorry, I now understand what you are saying, and yes that is true, but this should normally not have taken place suddenly. The OP mentions nothing of tinkering, just printing over SD card which lets me believe there is something structurally wrong with the end stops or something with the cable, connectors or the board. But you are right about inverting the end stop state using M119! Thanks for clarifying. – 0scar Jul 6 '18 at 10:27