Prusa i3 heatbed not working

I have some issues with the heatbed on my Prusa I3 clone:

The heatbed worked for quite a while and now it does not. I have checked the internet for troubleshooting and that's where I am now:

- checked the heatbed: resistance is about 1 Ohm (as it should be)
- checked the GT2560 board: fuses are OK, MOSFET for the heatbed seems to work correctly, output at the headbed plug is 12 V and the control LED is working when the heatbed should start heating. Thermistor shows room temperature.

The problem is: as soon as I plug in the heatbed the voltage at the output of the board drops to 0V and the heatbed does not heat. The control LED at the output is still on.

Any idea how to proceed?

AR

I would say the the MOSFET is bad and it is failing under high the current load.

Test the Hotbed
you can test the hot bed by connecting to a Car Battery charger 10Amps or better
you can use a UPS 7Amp Battery for a quick test to see if the hotbed actually works.

Finally found the problem: the interior of the plug of the hotbed was melted. Replaced the plug and everything is now working again.

Just wanted to post it because this might help someone with the same issue. At least this is an additional point which should be on the checklist for hotbed issues.

AR

I see you found the Problem, That was not a very obvious problem.

You would think by now Manufacturing Companies would use connectors / Wires that would handle the load they are designed to by now.

@Roberts_Clif

Since when have companies ever done the right thing vs the cheapest option they can get away with?

I have a cheap CTC i3 clone.

I am having a similar problem, but the control LED is not lighting. Would this suggest a problem with the GT2560 control board?

GT2560 are well known for blowing headed bed fuse

Thanks Dust,

The fuse had blown, but had to wait until today for new one. Bed started heating, but after a minute or so stopped heating. New fuse is still good, so board is no longer giving mintemp err at startup. MOSFET may have failed?

At any event can print PLA on unheated bed, so will be doing this for the moment.

I do have a mega2560 and suitable control board, which I could substitute, but this is in use on another project, and will not be able to swap it for a couple of weeks

Cheers

Clive