Twice now my Taz 6 has melted one of the purple wires that plugs into the heated bed. Same wire both times. I can replace the wire get maybe 10 PLA prints in and then it burns through the wire again. Any suggestions to keep this from continuing to reoccurre?
A melting wire is indicative of a short. Which purple wire? One of the thick ones with the 2 wire connector? Or the smaller connector with the 8 wires (those might be blue though). Either way though, I wouldn’t know how to trouble shoot this well enough to be helpful. An e-mail to Lulzbot support about this is what I suggest.
They are the 2 purple 16awg with Anderson power pole connector that plug into the heated bed. It has melted 1 of the purple 16awg wires twice now in the same spot approximately 4 inches from the bed connector. I removed it from the wire loom and and they are the largest wires in it. All other smaller wires nearby are completely unharmed.
So after talking to Lulzbot support then suggested replacing the internal harness and or the rambo board. Not having that kind of money, I got some high temp flexible silicone copper wire 14 AWG (original wire is only 16awg) and made brand new harnesses using Anderson power pole connector. I plan on adding an inline glass tube fuse in right after the wire exits the back panel. As of right now the bed is working just fine and actually heated up fairly quickly than it has previously. Will report back if another failure occurs.
Good deal! Always like them home made fixes, save a little money. 
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Hold up if the wires are melting I am curious what happened to the circuit board system but I would first have a electrical professional look at then look at the motherboard then see which wires have to be crimped
I looks like an old wire problem. The plastic covering gets brittle, gets a TINY crack in it and makes the wire start bending at the cracked outer coating. So basically metal fatigue of the wire bending right there, which reduces the wire gauge to the point the wire burns up. Happened on the original mini bed wires pretty often. The wire wrap helps but still can occur. The wire used is not really suited to flex so much like that.