Blown Board?

General LulzBot Mini
1

Hi,

Lulzbot mini standard. Took apart the heater unit cos the PLA I introduced after using ABS got stuck. Reassembled everything, went to run a print as normal and found that the probing didn’t function correctly and the printer was trying to print about 25mm above the bed. When attempting to probe, the head moved to all four corners as normal, moved down slightly to probe but didn’t touch, then up again. I initially tried reinstalling the firmware, doing a quick print and uploading a standard PLA profile but to no avail. I then sent an M119 command and found that the z min was always in a triggered state. I read that the trigger is provided by contacting with the nozzle and bed washers. I measured the voltage between the nozzle and washers, all showed 2.33v which I also understand should be 5v. I’m assuming this is set up as a pull to ground switch. I also read that if the heater cartridge wires make contact with the heater body, this can cause the excess current to be applied to the board and damage it, maybe this is what happened in reassembling… Is this what is likely to have happened…? I’d like to confirm before I purchase a new board…

Incidentally, the close proximity of the heater cartridge wires to the heater body is a bad design IMHO… :grin:

Thanks

2

Yeah to be fair it is. But the newer designs are looking to what E3D are using with cartridge style heaters and thermistors so this should not be a problem in the future.


But yes, i believe you have a short between your heater and thermistor and that causes you board to act funky. If you fix this short it should go back to normal i think.

3

Not sure what they can do about that… the heater cartridge needs wires. :slight_smile: And the wires should he stiff enough to come out fairly perpendicular to the hearter block. Wire loom close to the heatsink should be fine.

4

Well the nozzle is a input to the RAMBo processor, the 2.33 volt reading does not bode well for the health of your control board. If you have a Ohm meter measure from the nozzle to the washers(with the printer unplugged), and you should read over 5000 Ohms or more.