Question: Low voltage on Heat Bed terminals?

Hello everyone;

Printer: 3Up V2
RAMPS 1.4 board

I'm trying to troubleshoot what I think might be a problem with my heated bed: The bed heats well to about 60c, then from 60 to the target of 65 it takes about 30 minutes. I have 12v going into the board, but the voltage taken at the Heat Bed terminals is pulsing between 3 and 4 volts.

Is this normal? If not, any ideas on what I should do next?

Thanks in advance;
Joe

So if I understand correctly the voltage read from the D8 output of the RAMPS is 3-4 volts? If your meter is reading that correctly than yes you have a problem. Your output should hover at around 12v at the bed. I'm not too familiar the electronics of the RAMPS but it sounds to be a blown MOSFET assuming it is receiving 12v

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Prusa i3 Rework - Ramps 1.4 - E3d Lite6 - Full Graphic LCD Controller

It might be voltage loss across the wires, when you measure 3-4V directly at the heatbed solder joints.
If it's 3-4V at the Ramps terminals, check your 5V regulator of the ATMega. It might not provide 5V, so the MOSFET doesn't switch ON fully. ( FET gets very hot then! )

Thanks for the replies.

I'm still a newbie, but after messing around a little more I think it might have something to do with my software settings versus a hardware problem. I think I need to experiment a little more before I start changing parts out.

Appreciate the advice!