Sanguinololu 1.3a 1284p - no power at heatbed.

Hi.

Im new in 3d printing and im trying to finish my mendel Prusa with Sanguinololu 1.3a and i have a problem.

There is no power at heatbed. I measured power on hot-end - there is normal 12V. When i measure the power on heatbed there is 0

What should I check? What may be a problem?

You gave us very little information. It's hard to even guess what's going on.

But most likely you have something misconfigured in the firmware (pin layout, thermistor type) or some wiring issue.

Thanks for your reply.

I had uploaded marlin from 3 different sources and tried to heat the bed. Every time there is 0V on Sanguinololu pins.
When i plug the heatbed to the extruder connector it get hot in just seconds.
I have tried to heat the bed in Pronterface and Yarrh.
The wiring is not the case, becouse i check the voltage on Sanguinololu pins.
The Termistors are 100k EPCOS and that's the type which i set in Marlin.

What about pin-layout? Can you tell something more about it?

Thermistor pin:

TEMP_BED_PIN 6

Heater pin:

HEATER_BED_PIN 12

Things to check:
- make sure the temperature is reported correctly (should be same as hotend at room temp)
- make sure the gate pin is set to high on your mosfet when the heatbed is supposed to be on (if gate is high and 0v on heat bed output, maybe you have a blown mosfet; if gate is not high, then most likely the pin is set incorrectly in firmware)

Agin thanks for Your reply.

The pins are set right in Marlin.

The temperature shown in pronterface is the same as room temp (T.25.0)

Now i would like to apologize for my lame... but in not good in electronic stuff. So i tried to check mosfet by simple voltmeter.

I put one end of voltmeter to the "Drain(Flange)" as show on picture attached to this post and other end to the "Gate".

On Hotend mosfet measured by this way - there is 5V.
On Heatbed mosfet measured by this way - there is 0-0,3V.

Did i checked mosfets right? Does it mean, that the heatbed mosfet is blown?

Problem solved.

MOSFET wasn't an issue.

The uploaded software was an issue (i think?). Honestly i realy dont know what was the problem . After several uploads of Marlin it started to work.