TAZ 5 Heated Build plate Connector very hot and smells like magic smoke

Currently the HBP on my TAZ 5 is still working, however the connector and wiring leading to the y axis has began getting almost too hot to touch when in use. You can definitely smell a hot electronic smell also. No issues from rambo and HBP seems to be functioning properly. Things to check before i swap out to a different heater / plate?


I would recommend contact our Lulzbot Support team. Due to the issue you are having I would recommend keeping the printer turned off until you speak to one of our techs.

Please contact us at: support@lulzbot.com

Thanks Nick. I’ll fire off an email.

I think you have the same issue than me : https://forum.lulzbot.com/t/adjustable-heat-bed-glass-mount/38/1

Can you see burned wires inside the box ? the two purple wires…

“… magic smoke” :slight_smile:

Finally pulled the TAZ apart to find the culprit. Looks like Pin 2 on the Heated Bed Connector has been getting mighty hot. The purple wire on both sides was fused it’s neighbors and the socket on both sides is melted. I’ve had several beds on this printer and never had an issue until this latest one. I wonder if the heater core is drawing too much current. If my math is correct 100% duty cycle should pull 25 amps. I believe my settings should be pulling right at 20 amps.

Hopefully it is not pulling that much through the 15 Amp Auto fuse.

I experienced something like this when replacing my PSU. Went with a 650W unit and I smelled burnt plastic for the first 1 or 2 prints. Opened the electronics enclosure, and did a quick scan with the thermal camera. The heat bed wires were glowing hotter than the rest…

Thing has been fine since those first few prints.

I don’t have a clamp meter to check amperage so that was a theoretical number. I’ll have to try to measure it this weekend.

Looks like I joined the TAZ 5 magic smoke club today. I want to thank everyone for the helpful information in this, and related, threads. It looks like I’ll be rebuilding the heated bed harness and external cables I think I’ll use thicker wire and solder the pins. I’d actually like to get a six pin connector and split the heater current over more pins. I guess I’ll have to research connectors now.

I think I’m going to try these. They claim to be rated for 20 amp http://www.ebay.com/itm/1pc-New-Aviation-Plug-4-Pin-16mm-GX16-4-Male-and-Female-Panel-Metal-Connector/360914891604?_trksid=p2045573.c100506.m3226&_trkparms=aid%3D555014%26algo%3DPL.DEFAULT%26ao%3D1%26asc%3D41376%26meid%3D93c2fbcff661457c8443d576e4cb69b8%26pid%3D100506%26rk%3D1%26rkt%3D1%26

Yes, that looks like a good option. I think I’ll order a couple and check them out more closely.

Well, I got replacement connectors from Digikey and repaired my existing cables. I did have to replace the connector shells, as the scorched pins had fused themselves with the plastic and could not be removed. I added solder to all the crimped connections for the heater power while I was at it. With the repaired cable I can feel a slight warmth near the connector when the heater is powered.

I also bought some of the connectors that piercet mentioned and built a new cable and harness using that. I printed an adapter for the panel mount connector, and I reused the threaded, brass inserts from the old, burned out connector. With the new cable I don’t notice (by hand) any warming of the connector when the heater is powered.

Here are a few pictures.

Edit: I’ve added the FreeCAD and STL files for the adapter plate.
TAZ5_Heated_Bed_Cable_Adapter_Plate.stl (43.4 KB)
TAZ5_Heated_Bed_Cable_Adapter_Plate.fcstd (13.2 KB)

Neat, can you post your adaptor STL file? That turned out pretty slick looking

I just added the STL and FreeCAD files to my previous post.

Folks, just had this same issue happen to me. Piercet was kind enough to point me to this thread. Luckily I did not blow up anything my mainboard.

New plugs on order.

Thought i would also add this juts happened to me and Piercet (aka the Lulzbot Legend) put me onto this thread. Looks like mine is pretty much the exact mode of failure as above. Have the connectors on order and will be making this mod too :slight_smile: This forum rocks!!