help! Printer down, power cord heating up like crazy.

I've had my Robo for a little over a month and am having issues with the electronics. Nothing on the printer has worked for about two weeks now, here's what happened and what I've done to troubleshoot so far. Any help would be appreciated. I've bought multiple replacements for the Taurino boards and RAMPs and have lost those in the process. I really want this thing to print again.

1. The issue started right after installing the E3D hot end. I did not touch any existing connections to the RAMPs board. I did piggyback the wires to the 12V fan that cools the barrel of the E3D onto the input wires from the power supply into the RAMPs header at the RAMPs header terminals. I saw this in a youtube video so I hope it didn't cause the issue.

2. I turned the power on to the printer after installation of the E3D and the hot end heater cartridge immediately started heating up and could not be turned off in Repetier. The printer was on like this for about 1 minute before i took the power cord out. Both the power cord and USB to the computer were hot to the touch at this point. I checked wiring for loose connections and disconnected the heater cartridge so I could multimeter check the voltage instead of the heater getting crazy hot. When I turned the printer back on I could not communicate with the Taurino and the USB cable started getting hot again. There was 12V running across the heater circuit at this point. I then unplugged the power cord which was so hot it felt soft and was almost melting.

3. I then bought a new Taurino board and installed the Firmware with no problem. When plugging it into the RAMPs I had the same issue with the USB and power cable heating up. I also lost communication with this new Taurino. I read up on the RAMPs board and with my issue of the heater being always supplied 12V, I figured I must have a short on my RAMPs board and order a new Taurino + RAMPs.

4. I flashed the firmware on the new Taurino and wired the RAMPs up last night. When I turned everything on I had initial communication between Repetier and the board (Repetier at least recognized the firmware version on the board.) I was able to turn on the heater but none of the motors. After about 30 seconds I lost communication with the board again. The USB cord was not warming up this time but the Power Cord going into the back was wicked hot.

I'm a mechanical engineer and am starting out with building and troubleshooting electronics. I've been reading up on the reprap wiki on the Taurino and RAMPs board but am now afraid its the power supply. Any one else have any power supply issues like this? I can't wait to be printing and not pouring money into troubleshooting it and frying boards.

More importantly, I want to have to confidence that it's safe to run without aiming a fire extinguisher at it whenever it's plugged into the wall

 

Sounds like you have something shorting in or attached to the power supply.
I suggest pulling it and doing some voltage tests with nothing connected, then attach just the ramps/taurino (with nothing connected to it but the power supply) and test your voltages again.
If that looks good then you can try testing each stepper and heater individually and work your way from there.

 

Thanks! I ordered a new power supply and cords and am going to troubleshoot everything tonight. Hopefully this printer will work again after replacing every piece of electronics on it.

 

One other note, check your cables for possible shorts first before plugging them in. Make sure the end connectors are not loose or have any frayed wiring.

 

+1 The were several instances of compromised insulation on my printer.