No voltage going to heated bed

[HoosierCruz]

Hi everyone,

I just got a new RAMBO board in the mail and finally got everything working. I pre-heated the bed and the nozzle which started to work, but the bed cut out around 45 deg C and now it won't come back on. I took my multimeter to the heat-2 bed terminals on the RAMBO board and zero V. Both the hot end and PEEK fan were running 12V as normal.

Any ideas?

I re-flashed the software and still nothing works.

Thank you for your consideration

[Earthbound]

Most likely problem is blown fuse. Fuse F4 (the 15A automotive type blade fuse) is for the heated bed circuit.

[bubbasnow]

while you got your multimeter go ahead and check for incoming voltage also. if you got volts going in, none coming out the most common is because of the fuze. But why did the fuze burn? don't just replace it and test again, you need to find the source of the problem (shorted wire?).

[HoosierCruz]

thx guys, it definitely was the fuse. not sure why it blew, but I replaced it and everything seems to be working fine. Thank you!

[HoosierCruz]

Hey guys - the bed heat went out again and the fuses are fine. I checked the large 15A fuse and the microfuse and they are both perfect. I took the bed off and no wires are crossing and everything is soldered solid.

My multimeter still says no voltage when attempting to heat up the bed.

Any ideas other than the fuses?

thanks a ton

[bot]

Did you check the green screw-terminal to the rambo board? I bet it's black and gooey looking.

[HoosierCruz]

Hi Bot - actually the board looks perfectly fine. The first time this happened, the terminal for the black wire to the bed was melted over and cut the circuit. But I just checked again and my RAMBO board is perfectly fine.

[bubbasnow]

But why did the fuze burn? don't just replace it and test again, you need to find the source of the problem (shorted wire?).

[HoosierCruz]

I triple checked my wires and all are soldered correctly in the right place (and covered in kapton tape). All of the wire insulation is intact.

Is there anything else to check?