Can my old faithful Mini Rambo 1.3a serve me longer?  

Can my old faithful Mini Rambo 1.3a serve me longer?

Hi everyone 😀 

My poor Mini Rambo 1.3a board has been through a lot, and the bed heater pins on the board have finally given up.

I don't mean the plastic terminal block has melted or the fuse has blown - those have happened before and parts been replaced, as well as wires soldered directly to the board. I mean the pins no longer receive current when read by multi-meter, and no LED is lighting up to indicate that current is being sent to the pins.

This is a bummer because as a last ditch effort I did try the MOSFET mod (a bit of a brain fart considering, should have done the mod sooner), but with no 12v going to the pins, the MOSFET gate never opened.

So! After trying my luck with Prusa chat support I thought I'd ask here - do I have any options left before the board becomes a very nice paperweight?

I have managed to successfully breadboard a circuit to control a 5v MOSFET using the part-cooling fan pins - controlling an LED brightness using the LCD menu fan speed control was amusing for a moment, but ultimately not a solution unless I was willing to dispense with the part cooling fan.

The MK2 to MK2.5 upgrade takes up quite a few of the remaining pins on the Mini Rambo - are there any viable pins left to control the MOSFET with? Could I do something like swap the left fan to other pins and use those to control the MOSFET? Does a pin need to be PWM capable to be a candidate, or can any pin be PID controlled with the right firmware modification? And lastly, I couldn't get a good read on fan pin voltages, are these pins 5v or 12v?

Hoping one of the great contributors here takes an interest in this, thanks in advance!