Mini 1 stalling

The person at our makerspace who has been caring for our 3d printers has left the organization. I’m taken on trying to get a Lulzbot mini back in operation.

I found and corrected a few problems but have not been able to solve a stalling/freeze issue.

When I send a print to the device, it does the cleaning pass, and then starts to read the bed position. It reads the first bed washer (back left) and starts to move forward toward the front left washer. Then it freezes and cura locks up. I’ve checked the belts, and the endstop switches. They all seem to work as expected until I send a print.

The console reports

Error: MINTEMP triggered, system stopped! Heater_ID: bed

Error: Printer halted. kill() called!

Unexpected error while accessing serial port. read failed: [Errno 6] Device not configured

Any suggestions on where to go next?

Sounds like you probably have a bad connection in the wiring to the bed heater or to the thermistor that reads the bed temperature. One thing I’ve done is just turn the printer on and watch the bed temp on the LCD, if you have one on the Mini 1, while slowly moving the bed back and forth manually with the motors off. Often you can find a point where the temp reading jumps around or goes to zero. If so, you have an issue with the wire harness.

I have 4 Minis, and they all seem to have this same issue. I have changed the beds previously on three of them, and think this may be my issue. I am not great with wiring, but would appreciate if you have any tips on how to fix this issue.

The heater and thermistor (temp sensor) are one pad. But it’s easy to swap it out.

If you look at the photo, notice there are just two plug connections. One is the heater and the other is the thermistor (sensor). To swap it out, you’ll remove the glass plate (remove the bed corner washers), disconnect the old bed and install the new bed. The wire harness is kept tidy with a zip-tie … so you’ll have to nip off the old one and replace it with a new one.

Installation instructions are on the bottom of that page. But here’s a direct link:

https://ohai.lulzbot.com/project/mini-replacing-bed/