Heat bed is not heating


The heatdbed is not heating. Extruder works fine.
When I change heatbed with extruder on the controller unit - heatbed shows immediately room temperatures. Extruder shows “0”.

Can you help me?

Can you measure heated bed resistance at the connector, should be about 7-8 ohm?
Also check on the PCB itself, to rule out wiring problems.
If all OK, then we suspect a problem with the controller board.

Hallo Velleman support team,

First, thanks for the fast and competent support.

I have measured and both connectors shows either 6,9 or 7,0 Ohm.
I have once again checked the wiring. The wiring ist correct.

Is there a way to send in the Controller Board for correction or what do you suggest.

Thanks in advance

Then we have to suspect there is a problem with the board.
You can return it to your Velleman distributor or direct to:

Velleman Projects Tech. Dept.
Legen Heirweg 33
9890 Gavere

US residents: please call (817) 284 77 85

Make sure to include a fault description, as the people that moderate the forum are not the people that handle repairs.

I have the same problem.
I made about 6 to8 prints without any problems and suddenly
i received following faults.
No start signal detected -forcing start.
communication time out
reset send buffer block.

no more tempature on screen of the heated bed and no heating of the extruder and bed.

Dear Telemaster.

Check the NTC sensor of heater (hot-end) and also the NTC sensor on heatbed.
Check also the wires of these sensors. Maybe a bad contact, or shortcut.

Best regards,
Velleman Support

Dear support team, I have exactly the same problem with the bed. The MOSFET for the bed won’t work and the LED does not light up. The nozzle on the other hand heats up correctly, and the bed heats up if connected in place of the nozzle on the print, so the bed itself works and the wiring is OK, and so does the thermistor in the bed. All the motors work too. I measured with the multimeter but found no power on the MOSFET of the printbed connection itself either.
What can I do now to check whether there is a fault on the board, and if so what do I do then? Thanks in advance. Maarten

Hello @mgk !
Maybe this will help if you understand schematics : https://reprap.org/wiki/3Drag_controller
This is normally the same motherboard for the K8200 !

Thanks for responding so quickly! That schematic is about as I thought it was then. So let me rephrase. Based on my tests and measurements I think the mosfet 2 for the heated bed does not work (or something else is broken on the print). I checked and it’s well soldered to the print (someone on whadda managed to get the thing going after resoldering the mosfet). What do I do now? Cheers, Maarten

I am only an electronic beginner. So be critical /check before doing what i say, but i would try :

Following the tracks, from the connector to the IC. Check the led, the resistors, with multimeter continuity check and or ohm resistance. After that if nothing is odd, find a video like this one to check the MOSFET https://www.youtube.com/watch?v=ivD5HR6EgUQ with that you could determine if this is due to a problem with the IC or some other component.

The lowest price I found for this motherboard is at: https://store.open-electronics.org/3D/3D_electronics but I have never tested this vendor.
And maybe you just need to change the MOSFET …

Edit : are you using Velleman’s firmware and not another or a modified version ?if not, you should try with an original firmware version of velleman!

Hoping this helps !