How to fix RAMPS 1.4 X Axis end stop short circuit?

I'm having some weird issues with the X axis motor. It will only travel / step on one direction.

After lots of testing I finally figured out when I do M119 with NO end stops connected I get the following.

>>> M119
SENDING:M119
x_min:H y_min:L z_min:L

When I connect an end stop to the upper two pins of the normal X axis it still says the x_min is high, regardless of the switch being on or off. If I switch it to the lower pins of the X axis the board reboots when I press the X axis switch.

If I connect to the Arduino Mega with the RAMPS board completely REMOVED and run M119, I get the exact same output.

So there appears to be a dead or hot pin that's configured for X axis end stop.

I'm thinking I should recompile the software to use a different pin for the X axis end stop, but not sure if there's a physical way to fix things instead. It's 2am right now, so and I don't have a meter with me. I can get one tomorrow.

Any tips on how to fix this would be appreciated.

Using Arduino Mega, RAMPS 1.4, A4998 drivers and very early Sprinter firmware.

Agreed its an issue with your mega

Examine it closely, look for solder blobs or bridges, it should be clean like this big image I found of a mega [www.elegoo.com]

xmin is on D3, pin 7 of the cpu, with power connectors on the left of the board, its the left hand side of the main chip near the capacitor
Also check around the D3 pin of the connector for shorts

yes checking for shorts from d3 to d2 and d3 to d4 and d3 to vcc might show you something

yes you can program around it to use annother working pin.

... caution!!!

Quote

... the board reboots when I press the X axis switch.

This is mostly due to wrong inserted end-stop pug! - if you short GND to +5V (with "turned" plug), then most likely your voltage regulator will burn and smoke!!

The other issues could be with wrong pin assignments or not correct set polarity ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

CAUTION is Indeed needed when working with the ramps controllers.

I do not have a Ramps though it is ramps compatible, I had an open trace on the circuit board that had to be repaired.



As you can see after I removed the silk screen you can view the jagged broken trace " Center photo ", Soldered a bridge over the break and the board worked perfectly.
This was difficult to see with the silkscreen on, so I had to use an ohm-meter to determine the trace was in fact broken.

FYI
Good luck

Edited 2 time(s). Last edit at 11/04/2018 09:17AM by Roberts_Clif.

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Computer Programmer / Electronics Technician