Electrical Short

Well, I messed up! I was cleaning the nozzle on my Taz 6 with a wire brush while it was on and I accidently brushed up against one of the wires and I saw a spark, then the screen went blank but the printer stayed on. I tried to power down, then power back up. The machine comes on but no graphics on the screen.

I know I screwed up. Does anyone have any suggestions as to what replacement parts I need to get?


If you are very lucky you blew up the two small grain of rice fuses on the Rambo board, probably the thermistor and the heater core as well, all of which will require about a total of $10 to replace. If you are unlucky, you fried your Rambo board and will need to replace that $180 part.

Never ever ever use a wire brush on a Taz nozzle. But you know that now.

Yes. I have absolutely filed that one away as “live and learn”. Can I ask how one would test to see what was damaged?

Thank you.

Also, if it was only the thermistor and/or heater block, why would it cause the screen to go dark?

You applied 24v to either the thermistor or the z minimum endstop connectors, which probably blew up the small fuses on the rambo, one controls motion and the other controls accessories, like the lcd. The larger 15a automotive fuse controlls the bed and should be undamaged. The concern is that depending on what you shorted, you may have also blown up the thermistor too. The heater core is less likely to be damaged, but it may have arced and damaged it’s casing or internal element. To test the fuses pull them carefully from the Rambo (it is possible to accidentally pull the circuit contacts and destroy the board, I found that out the hard way once) and use a multimeter to measure resistance. You can look on YouTube for a fuse multimeter tutorial if you like.

The dark lcd is almost certainly the fuse or the Rambo board. There wasn’t enough voltage to burn yhe back light most likely. It’s quite likely the thermister may also be damaged if that was what you shorted to. You can test it also by measuring resistance, the proper values should be somewhere in this forum.

Measure resistance across the fuses with it off. You’re looking for zero ohms, or very close.

Or measure voltage across the fuses with it on. You’re looking for zero volts, or very close. If the fuse is open, you may read the supply voltage across it.

I hope you just popped a fuse. And a trick I’ve seen is to simply solder a new fuse across the old one. Sometimes desoldering isn’t worth the extra effort. Replace it with the same value.

The fuses aren’t soldiered in, they are just press fit in sockets.

The guys from Lulzbot requested that I switch the F2 fuse to the F3 fuse slot and vice versa. Turned the printer on and the LCD screen comes on! Now I know it was just the fuses, so I will replace them both and be back up in no time!

Thank you to Lulzbot Support Team! I promise you all, I have learned my lesson…NO WIRE BRUSHES!!! If I need to clean the nozzles from now on, it will be with a Scotch Brite scrub pad.