Sanguinololu Not Heatng

Just soldered up my first Sanguinololu 1.3a. It came with FTDI presoldered and Marlin loaded. I have it connected to Pronterface and everything works (well z is inverted) except the heaters. My thermisters sit at room temp (14C) and neither the heated bed nor the hot end will heat. I have inspected my soldering on the MOSFET's and it all looks fine. Firmware problem?

Scratch that.

You know when I said I checked the soldering... I may have neglected to check which way around the MOSFET's are supposed to be. I just copied my Printrboard. I am about to find out if I have killed them.

Probably not because the gate would be grounded turning it off so no current can flow. So my guess would be that they will survive.

Edited 1 time(s). Last edit at 08/11/2012 08:09AM by nophead.

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[www.hydraraptor.blogspot.com]

Cool, haven't been able to get them off yet

Got them off and flipped them round but only the hot end one worked. So only blew 1 out of 2 considered myself lucky.... until I replaced it with a brand new one that also doesn't work. I have no idea what the problem is now, the only other possible culprit is the molex header but the soldering is perfect and its not exactly like you can have a faulty header right? Not sure what to even try.

Edited 1 time(s). Last edit at 08/21/2012 04:25PM by RegionX.

Should I repost in Sanguino? Just thought I would have more luck here being busier.

best way to check for problems is just run your finger around the board if something has shorted or been put on backards it will be getting hot.

you need ideally to get a multi meter and check your voltages from one side of the mosfet all the way out to the molex see were it stops.

if you were shorted and pins were getting very got it may have melted the conector or may have tarnished the metal coating. as they are very low rated pins for heated bed (3A pins should be much much higher (7-10A). Have a look if they have tarnished give them a scrap and get them shiney. also check the pins on your wire side for tarnish and of cource make sure you have connections.

just to note when you say heated bed is not working make sure you check it with your hand for heat ! dont trust the LED as that has to be wired correctly to light up were as the heated bed it self will work which ever way.

also also make sure you solderd to the correct side of the heated bed ! only 1 side has working contacts the the power wires !

Thanks for the response, I will get the old multimeter out and see what I can do but to be honest I not sure what the voltages should be?

Basically I plugged the bed in to the hot end MOSFET and it heated so definitely the bed is working and its also definitely not the MOSFET itself as I have now tried 2 different ones.

I will also try swap out the right angled header but I doubt that is the problem.

The only things involved are the pin on the Atmega, the tracks on the PCB , the MOSFET and the connector.

Does the Amega pin go from ~0 to ~5V when the bed turns on?
Does that get to the gate of the MOSFET?
Is the source connected to ground?
Is the drain connected to the bed?
Is the other lead of the bed connected to 12V?

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[www.hydraraptor.blogspot.com]

Kinda weird, I added an LED and resistor and all of a sudden it works. Bare in mind it did work before but in the hot end MOSFET so it surely can't be that. Any way for now it works, if that changes I will try everything suggested. Thanks