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Several RAMPS woes (melting connector, E0 not working, etc.)

Posted by TimAyres 
Several RAMPS woes (melting connector, E0 not working, etc.)
May 06, 2015 05:07PM
Greetings! Been having a right string of problems lately with a new Prusa i3 and thought I’d share. Any help or tips are very welcome!

This is a Folger Tech Prusa i3 from ebay, which uses the standard Arduino Mega & RAMPS 1.4 setup. Built a kit a few months back that is still running fine. Bought an identical kit for my son (built by him!) which was running well for a week till it would suddenly not power up a few days ago. Checking the RAMPS power inputs revealed that at the green plug-in screw terminal connector, the 2 pins on the left read 12v as expected, but the 2 pins on the right only read 2v. After wiggling the wires some the unit powered on. Clearly a bad connection; unplugging the connector revealed that the connector (mainly the 2 left ones) were melted! Uh-oh. Fortunately we had a spare, so I cleaned up the pins on the board side connector with contact cleaner, scrapped out the melted plastic, and installed a new plug-in connector on the wires. Everything seemed fine, until a few layers into the first print I saw smoke rising from the connector! Clearly my clean-up job was not sufficient, as now the right most (ground) pin was all hot & melty.

After reading several more reports of connector failures (check out the Safety & Best Practices category!), I’m now planning to install screw-in connectors like these. One overheating connector is one too many.

In the meantime, the easiest fix was to just replace the entire RAMPS board with a spare. That complete, now the Arduino would only power on while connected to a PC! Previously most printing was done stand-alone from an LCD. My first suspicion is that the voltage regulator has been blown, although I’m not sure how that could have happened just by changing the RAMPS board. Maybe a pin got broken or shorted during disassembly? I haven’t continued to troubleshoot yet, instead opting to just replace the entire Arduino with a spare (hurray for spares!).

Everything powered up fine now, however the extruder motor would not turn! After swapping the motor connector to a different axis the motor turned, so the motor & wiring is physically good. Swapping the stepper driver board had no effect. Next was trying the motor in the E1 spot instead of E0, which required a firmware recompile to tell Marlin that I have 2 extruders. Unfortunately, using the latest release of Marlin 1.0.2, after setting “extruders 2” I got compile errors! This seems to be related to compiler bugs per this issue. After upgrading to the latest development version of Marlin I could successfully compile with dual extruders. After plugging the extruder into the E1 spot (with its original stepper board) the extruder is working fine. And this is where I’ve stopped at the moment.

In the short term the plan is to configure Slic3r, etc. to use dual extruders, but just print everything with extruder 2 (E1). Slightly longer term, I may recompile to set the E1 spot as E0 and go back to just a single extruder compile (to simply my Slic3r configs). Will swapping the pin callouts between E0 & E1 in pins_RAMPS_13.h do what I want?

Longer term, any ideas for how to troubleshoot the E0 position? I’m not quite sure where to start there, and Google hasn’t been helpful in this case. Any good test routines to verify Arduino & RAMPs operation before installing & hooking everything up?

Thanks!
Re: Several RAMPS woes (melting connector, E0 not working, etc.)
May 06, 2015 05:47PM
Check that your new RAMPS has the D1 diode installed, and that it is providing 12V to the Arduino voltage regulator.
Re: Several RAMPS woes (melting connector, E0 not working, etc.)
May 07, 2015 09:03AM
Yes, just swap the pins in the appropriate pins file.
Re: Several RAMPS woes (melting connector, E0 not working, etc.)
May 07, 2015 04:19PM
AndrewBCN, is that for the arduino not powering up issue? I didn't pull off the stepstick to check if the D1 diode is there, but I checked a supposedly identical board (bought at the same time) and the D1 diode is there, so I'm assuming it is. After replacing the arduino it is receiving power from the RAMPS board just fine, so that appears to be an arduino issue, not a RAMPS issue.

Had issues with the developement version of Marlin; the z axis would move fine when commanded, but when telling it to home it made a terrible noise and wouldn't move. Fixed by downgrading back to v1.0.2, swapping the E0 & E1 declarations in pins.h, and compiling with a single extruder. Now everything is running smoothly (with the extruder plugged into E1) and we've gotten several successful prints.

For future reference, I'd still appreciate any tips in troubleshooting the dead E0 spot if anyone has any ideas. Thanks!
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