I purchased a Taz 6 printer, every thing works fine but the heated bed. I get an error when printing, which cancels the print. If I set the bed temp to zero, the machine prints fine. Is there a test procedure to test if it is the bed or something else.
The reason I’m questioning if it’s something thing other than the bed, is because with all the items the seller provided was another bed. I’ve had a Lulzbot Mini 1 for years and never had to replace the actual bed.
First - the solder joints to the heater connections on the RAMBO boards are a known failure point: TAZ 6 Heated Bed Not Heating - Perplexing Puzzle - [EDIT - SOLVED!! Heater pin melted on RAMBo!] - #21 by kmanley57
If it passes that inspection, continue:
What temp does the display say the bed is when you turn the machine on? If you get 0° for it - could be wiring, harness, or thermistor. Plug the new bed into the harness and see if you get the same 0°. If you get a temp reading with the other bed, swap beds. If it’s still 0? look at wiring from the harness to the board. Check for continuity along both thermistor wires.
If the temp display is within a few degrees of the nozzle’s temp, the thermistor should be good, but heater could be bad. If you manually tell it to heat and it doesn’t heat up, could be wiring to the bed heater, the bed heater, or the control board. Follow wiring for continuity back to the board, if it’s all good, replace the board.
Thank you for the info, I work on it when I get home.
I know that when I start the system, I get a temp reading and not 0°.
Update, I have verified that I get a temp reading from the heater bed. If I set the bed temp to 60° via the display or software, I get the bed heating failed error. Below is the error from Octoprint. Is there an ohm reading I can get from the bed connectors to verify the bed condition, before chasing possible wire problems?
Another update, I started looking at the bed connections to look for obvious problems. I found the cable connector that plugs into the pcb has overheated and melted. Now I have a more questions:
a) Anyone know the manufacturer and part number of the cable connector?
b) Is this common, if so what could have caused this? How to I test to see where the damage is?
c) Can I power up the unit to see if there is any power at the pcb connector pins, if so, what voltage should I get?
Thank you!
The original bill of materials is on the site at https://download.lulzbot.com/TAZ/6.03/production_docs/BoM_KT-PR0041NA_OCA.xlsx
The spreadsheet is hierarchical, so you should be able to find the exact connector.
But definitely make sure the solder on the board is in good shape before just replacing the connector.
Still have an issue with my heater bed.
I replaced the cable connector that plugs into the PCB. I startup the Taz, and the display shows both temps within a degree or two. When I activate heating bed, I get nearly 20v at the bed large connector and 4.7v at the small connector, but no temp increase. Then after 1 or 2 minutes, the system faults and says to reset. I have continuity from the small bed connector to the PCB.
I pulled the bed from my Mini and connected it to the Taz and end up with the same results. This leads me to believe the bed isn’t the issue.
I assume something failed or shorted on the PCB, maybe a fuse or something??? What do I need to test now? Thank you.
Definitely check the fuses on the board. With your melted connector from before, there’s a good chance the fuse burnt out.
Thank you for the suggestion. Just checked and the fuses are still good.
I saw a thread that mentioned red led blinking when bed heater is on, so I checked that. When the bed heater is activated I see two red leds next to each other. The left led is solid red and the right led is blinking until the heater is halted. When halted the right led goes out but the left led stays on. Does this information help diagnose my situation at all?
Just wanted to follow-up. My Taz 6 is back up and running. After all the testing, and not finding anything faulty, I pulled the Rambo out enough to see the backside of the Heated Bed connector. Sure enough, one pin was burned, so I tried this work-around from this thread and it worked.
