Marlin help/advise

I have had a custom reprap using a ramps 1.4 for a while now it worked great for awhile. but recently for some reason the main extruder quit working. I have already replaced all the electronics and switched to a extra motor I had laying around trying to find the problem I even tried reloading the firmware. any advice would be greatly appreciated.

What exactly has quit woprking? Stepper? Hot end? If hot end the did you check its resistance with multimeter?

the stepper

Does the stepper motor have a plug in cable by chance? I've run into an issue with some of the cables will loose contact with a pin which means you loose a motor pole pair which will stop the motor from turning and it'll just buzz grind or hum. If you check with a multimeter that you have and ohms reading between the pairs. You should have two wires together will give you an ohms reading, and the other two wires will give you a similar reading while the cable is plugged into the motor. If you measure all 4 wires in different combinations and only get 1 pair with an ohms reading, you have a broken wire somewhere.

Then check stepper coils with multimeter.
[www.google.ru]

But stepper rarely burn out and you alreay replaced it.

Did you changes the drivers?
Need to see output from the drivers. For that oscilloscope is needed. The least you can do it to check driver power supply.
But you can plug this stepper into some other driver (for example, for X axis) and do G1 X1 and see if it moves.

Yes, and test the wires, of course. One by one, from one end to another end.

Edited 1 time(s). Last edit at 02/01/2017 10:50AM by ArtemKuchin.

The weird thing is that I know the cable and the motor is fine. because I connected it to the x axis and it worked fine. I also tried replacing the stepper driver on the extruder motor and I also replaced the ramps and arduino.

Okay, now do vice-versa: connect E driver to X motor and move extruder and see if X motor moves.

I tried that with one of my spare steppers that I know works and it only works when it is plugged into the x connector but not when it is plugged into the extruder connector

Aha, we are getting closer. Check that power is supplied to the extruder driver. +12V usually. Check board schematics/pcb layout/pinouts to find it.
As you said you replaces the electronics, but did no specify what exactly
Put a known good driver into E driver socket. Check if E works. If not - check power supply for the driver. If present then need to disconnect everything and test
every traces from Atmega to driver input pings. Use schematics and board layout.

Another option: if you have spare driver socket then use it and rebuild your firmware to use it as E driver.

Ok I will try that when I get home tonight i am thinking i will set the second extruder pins as the first extruder so that it thinks the second extruder slot is the first