So I have had my printer for about 3 months now but recently on one of my prints the bed would not heat up. I used a voltmeter to try and see if there was any voltage passing through the wires on the actual bed itself but the meter was not picking anything up. My next step was to unplug the bed and test the connections on the PICA. The meter here reads 1.2 mv when I set the heat at 40 degrees C. No matter what temp I put it on it still continues to read 1.2 mv. The D4 LED does not even come on when the bed is set to heat. I’m not really sure where to go from here but I would very much appreciate it if someone would help.
I’ve got a similar issue with my RAMPS.
After many prints, the bed stop working, and I can’t measure any tension on the connector of the RAMPS (the continuity through the bed is ok).
I ordered a new board and will see if it saves the problem.
I assume the Thermistor is reading the temp of the bed and showing similar temp to the hotend when cold.
If the ohms resistance is right on the bed you have to make sure that you are getting voltage from the board. Stick your multi meter on the + - power from the board (to Bed) it should be the same voltage as your PSU… so if you have a 12v PSU it will be about 12v and 24v would be 24v.
If voltage drops down well below the PSU voltage you have a power supply issue and it cant supply and breaking down.
If the voltage is right and the Ohms is right then you have a broken wire. Which should be confirmed by measuring the voltage at the bed + - and should the same as the PSU voltage as mentioned above.
Oh and one small “gotcha” is move the bed back and forth while measure and you could have an intimittant break