Heated bed temperature is 738.8 degrees

Hello. My 3D printer software shows what my heated bed is over 700 degrees by celsius. What is the problem? Before 2 weeks I changed new heated bed.

This indicates you have a short in the wiring.
Check the resistance at the plug (wires) at therm 2 should be around 100K at room temp.

By the way, I can not to move heated bed, however then I press “home” button - it’s working. It happened today, the same time. So, problem should be the same, yes?

It sounds like it
When you unplug therm2 does the temp go to 0C in the manual control?

I checked everything and now it is working properly. Probably it was 100K thermistor short. Thank you.

No problem

Glad to hear it’s working again!

Hey I have the same issue but my bed temp. is at 145.40 ish. I unplugged the bed temp. sensor wires at the circuit board and it doesn’t change. The resistance of the thermistor is 121k ohms and will read fine if I plug it into the extruder header on the board. Does that indicate that I have a short on the circuit board? And if so is there anything I can do to fix it other then getting a new board? I have been running the printer with out issues too before the problem occurred.

I don’t think you can fix this on your own.
From your description it sounds like there is something going on with the board.

No, it was thermistor short. It was too close printed bed. My thermistor is another one than original on this printed bed. It is bigger.

So you got it fixed?

That geskill guy sounds like he got his fixed but that last post wasn’t mine. Mine is still broken and I am sending my board in.

I am sorry, I did not see your post before.
I think your problem will be board trouble or try to reinstall software.

Did you already send your board in?

If not, check if the SMD resistor on the therm port (not the thermistor) has 4,7 kOhms.

its all cool geskills

and ichbinsnur I did just send the board in and are you talking about R7 on the controller board needing to be 4,700 ohms? I measured R8 which is the resistor for the extruder I believe and got 4.7k ohms and I figured I needed the same for R7 which I think is for the bed. I only had 326.2ohms so I figured that was the problem but I emailed Velleman support and they were super nice about it. They should be hooking me up with my old one fixed or a new one so I am happy but I think if it happens again I will pursue trying to replace that resistor. Do you happen to know what may possibly cause one of the individual stepper motor drivers to quit working? Such as a common problem? If not that is cool I am just interested.

The most common cause for failed stepper modules is overcurrent (caused by wiring fault or incorrectly setting the output current) and/or overheat.

The driver chips have their thermal sink on the underside of the chip housing, so cooling them properly
mostly is a question of the carrier board design. (the PCB “should” have big copper areas in it to sink the heat)

To prevent mine from failng due to overheat i made a fan ventilated housing for the main PCB and
glued some small ic heatsinks to the stepper driver ic’s. (although the upper side of their cases is not the best spot for cooling)



Thanks I have seen a lot of other people make the fan enclosures and run the little heat sinks so I think I may do the same. I was just curious because when I fired my printer up the first time I had a little driver that didn’t work and switched it with one from a different axis and it worked so I ordered a new one and haven’t had any other issues with it. So it may have been bad from the start but I didn’t know if I did anything wrong and was just curious. Thanks for the info I appreciate it because it was very helpful.

You’re Welcome!

The driver boards don’t seem to fail immediately under stress, but as they ar cheaper mass products there is
a greater chance to find one bad right from start.