Heated bed has no power

Just finished putting together a new printer and everything is working great except that I can't get the heated bed to power up. All connections are good but there's no power at the D8 connector. I've double checked my firmware to verify pin assignments. I'm thinking there may be something wrong with the board, bad solder joint or whatever.

Any other ideas for things I can look at?

Gyv

Are you getting voltage on the ramps input side? Make sure you check the 11 amp rail and not the 5 amp rail. Also its a good idea to check out the voltage on each side of the fuse to rule that out as the problem. If everything seem OK, check if you are seeing an LED light up near the bed MOSFET when you expect the bed heater to be on. Unless you selected PID control over your bed, the LED should come on solid as long as heat is called for. If you chose PID, the the LED will be flashing.

I do have voltage at the 11A input and both sides of the fuse. PID is on, but no LED.

I think most people just use bang bang for the print bed. PID is a bit of overkill.

There's not much to the bed circuitry. A MOSFET and some passive components. The MOSFET is perhaps they most likely go fail, but before jumping to that conclusion you should check its voltage levels when it it supposed to be on. My problem is that I am away from home and do not have the resources on hand to be able to tell you what to check for. Maybe someone who reads this can let him know what voltages he should see on each pin?

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Gyvven
I do have voltage at the 11A input and both sides of the fuse. PID is on, but no LED.

Do you also have voltage (5V) on the MOSFET pin going to the ATmega pin? The other two MOSFET pins should have the same voltage as on the fuse when the bed is off. One 12V and one 0V when the bed is on. PID usually also gives a solidly lighted LED as long as the bed is cold, starting flashing when it gets close to target temperature.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

I changed it back to bang bang but I'm only getting 1.1mV on the arduino D8. So, I think I'm not getting anything off the arduino itself.

The arduino just provides a logic HIGH level to the MOSFET - that's what traumflug was asking you to check for. When the MOSFET sees this, it's supposed to open the gate and let the voltage from the power supply (via the 11 AMP fuse) get to the heated bed. When you say you're getting 1.1mv on D8, are you really measuring the arduino output, or are you measuring where it says D8 on the RAMPS. Where it says D8 on the RAMPS is not D8 from the Arduino. To measure the true output form the arduino, you need to check the input pin on the MOSFET. You can also just remove the RAMPS board, write a small sketch that just turns D8 high, and measure what you get. If you're only getting 1.1mv out of the arduino, then yes that's you're problem. But I have to ask if this ever worked? Maybe you don't have the correct pin assignment???