ramps 1.4 maxtemp problem after powrr pin burnt

Hi all,

Need bit of a sanity check as my ramps board may have got fried.

I had the power supply screw and plug connector burn this evening and cut power to the heated bed.
Print finished with no heated bed ok, amazing.

I replaced the burnt plug and socket on the board and at first it all looked good.
Ran everything up all motors worked as expected. Heated up the nozxle and bed.

But after a short while i got a max temp error and the marlin firmware cut the power to the heaters.
I reset everything and watched the smart display.
The bed heated up to about 55degC then the bed led started flashing then stopped heating.
The nozzle continued to be heated past its set temperature and headed towards max temp. So i reset the arduino mega.

I can repeat this now every time.
It looks like power is getting shut down on the bed and shunted to the nozzle heater bypassing the nozzle temp control.

Is this the mosfets breaking down?
How is the bed power getting to the nozzle and bypasding the nozzle heat control?

Is it just a matter of replacing the bed and/or nozzle heater mosfets to repair it?

Thanks

Gordon

You probably have a short somewhere in your RAMPS or one of your MOSFETs is shorted or the Arduino got damaged. Check with another RAMPS board. If you still have the same problems, check with another Arduino.

Feel like slapping myself round the head with a wet fish.

When i dismantled everything to solder on the new power plugs.
I switched round the leads for the bed and hot end.
So of course the bed cut out when the hot end got to temp and then the hot end continued to heat till i hit maxtemp.

Not paying enough attention.
Dont know how i missed that.

Gordon