Voltage drop on Rambo to hot end very low

[jeffhuber]

So when I try to heat up my hot end - it heats up soooooo slow. I have another Max v2 that heats up very quickly.

I measured the voltage across the hot end on the Rambo - and it shows up at .82. On my other max it's over 10.

[img]http://i.imgur.com/dAELsnc.jpg?1[/img]

I checked all the splicing from board to hot end and the power connection. Not sure what to try next.

Thanks for the help!

[Eric]

http://reprap.org/mediawiki/images/9/91 ... ematic.png

Is the associated LED lit? I wouldn't expect it to be if it were really under 1V.

If you're testing on the screws, I'd verify by testing where the wire enters the connector. Normally it's the same, but worth a shot.

The mosfet controls the ground side of the circuit, so verify one of the pins is actually 12V when measured against the power ground.

If you disconnect the hot-end wires, does the behavior change? If not, then you're looking at either the rambo hardware or software.

Are you sure the output isn't turned down in software, either by mistake, or intentionally because it's already hot? You can try manually controlling the output (control panel and/or gcode) to verify the hardware. Hot end doesn't need to be connected.

[beyic]

Jeff, I have serious doubts on your measurement actually. Since you wouldn’t have gotten it heated up at all if it was just 0.89V. There might be some issue with the current sourcing capability of the power supply circuit though. Where it was only able to supply a limited amount of current which therefore made the voltage value to get considerably lowered. This is usually called loading. Kindly check for any burnt components of un-connected resistors.

pcb assembly

[Stephen]

I'm having the exact same problem as jeffhuber. My printer was working great for about a year and I was printing lots of prints. In the middle of a print my extruded went cold.
I put a new heat cartridge on.
I put a new fuse in (not needed)
Finally I checked the voltage on the "heat 0".

I'm getting low voltage .6 - 1.2 volts.

Any ideas?