About to Trash Taz Pro After Print Head Repair

After two years of success and failures post upgrading from the Mini to the Taz Pro back in 2021, I have reached my limit.

I greatly regret upgrading from my mini to the pro, over $4k spent on this and had had nothing but challenges with it.

Long story short, had a bad abs print run that molded into my print head, my son swapped to ABS without realizing and well it was a mess. After a $400 dollar print head repair, I reconnected everything and the printer now halts on any commands to the print head.

it wont auto home, and when i try get it to calibrate it halts on an error. I upgraded to latest firmware and still no go.

Long story short, it fails on homing and halts and says reset printer. Any advice appreciated before I just trash the whole thing.

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If you can video the entire startup to homing sequence, that’ll help us here a bunch.

The Pro uses sensorless homing for x & y, so anything that interferes with movement can cause an error there.

If it can’t hit the top two z limit switches simultaneously due to an off-level gantry, that’s a simple fix.

Clicked on home button in cura and on device same results

Also, It won’t let me upload a video from my phone says it’s wrong file type

Your gantry is at the top. Which axis homing does it fail on? The Taz Pro will home Z, then X, then Y.

All of them so Z first i wager. The thing that doesn’t makes sense is the unit also now
Reboots whenever I try to set a temp to load filament

You should probably start by downgrading the firmware to the original version the printer shipped with and downgrade the software on you computer the the cura version that was current when the printer shipped as new.

The biggest problem I have had with all my lulzbot printers is the “upgrade firmware” option - most are very sensitive to the cura version it’s loaded from and can cause numerable problems with function. Best to turn off the “upgrade” nag (buried deep in the settings).

The old adage holds true with lulzbot printers “If it ain’t broke, don’t fix it”. Most of the firmware upgrades are pretty irrelevant to putting plastic down where your solid model needs it - stick with what works and leave the tweaking to those with way more time on their hands and nothing particularly important to make.

Post to youtube and put a link here. If you’re uncomfortable posting publicly, post unlisted and you can DM myself and a few of us here.

The error when setting a temp is usually going to be due to a thermal error, and is a good thing when compared to what would happen if it didn’t shut down.
Either your heater or thermistor isn’t working. This is due to one not being plugged in, or having a broken wire. What does your temperature read when you turn it on? If you have 0 / 0 C on the display, that’s definitely thermistor failure. If it reads room temp, something like 25 / 0 C, then after setting temp remains at 25 / 200 C, and stays there before throwing a failure, that likely a problem with the heater.

Basically, if you set a temperature, the thermistor should be reading a rise in temperature. If it sees no rise in temperature after a few seconds, this indicates that it’s not reading temperature correctly, and will shut down the printer. If it didn’t do this, and was just reporting room temperature for the hot end temp, the system would be sending full power to the heater, and without the thermistor reporting it had been reached, it would quickly reach temperatures capable of causing any nearby plastic to melt and possibly ignite (thermal runaway).

The wires to the thermistor are particularly fragile, and the usual culprit, but wires to the thermistor and heater are both easily damaged, especially when you have a giant blob of plastic encase the hot end.

You bring up a good point. The firmware/curaLE version definitely needs a “Long Time Service” stable combination option from Lulzbot that’s updated when there’s a significant enough change that warrants it… so like every 1-2 years? Basically a “This is what ships with new units. It’s confirmed to be working. Every other version is assumed to be a test version for advanced users.” option.

On paper they have the stable and development versions on the site, but in practice, they are not stable at all. There should be Stable, Development and Nightly, and the Stable should strictly enforce a matching firmware, startup and shutdown gcode just so those variables can be removed when troubleshooting. Development would unlock the startup and shutdown but otherwise be the same, but at least we would know that somebody using the Stable version with a generic profile didn’t inherit a problem caused when somebody tweaked the startup code to try and fix something that wasn’t broke and never changed it back.

With so many errors related to the toolhead, it sounds like you maybe just have it connected wrong or a problem with the harness.


Thank you for reaching out to us over in support. I am glad to hear that this issue was just stemming from that popped fuse!

If you had any other issues, do not hesitate to reach back out to us!

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Do you mean the fuse on a mother board that is exactly why there needs to be a upgrade for a small
circuit breaker as a option it would be easier for the user if you kindly do not mind that for feedback