jsc wrote:Okay, try this.

In Configuration.h, set EXTRUDERS to 1.
In pins.h, set HEATER_0_PIN and TEMP_0_PIN to the values for HEATER_1_PIN and TEMP_1_PIN, in the RAMBO section.

Thanks! I discovered I also need to set the extruder pins (or rewire the extruder engine).

jsc wrote:Just don't plug anything into Tool 0 and set up the slicer to use Tool 1.

Marlin detected nothing connected to Tool 0 and stops the printer.

I am trying to find how to configure Marlin to a single extruder (easy) and to use Tool 1 as though it is Tool 0 (should be easy but didn't work)

Can I configure the machine to use a single extruder (Tool 1)? So I can do some work until I get a new board

Alas, a shorted MOSFET behaves that way: always on. Yes, I think that's the likely conclusion. So after much trial and error, the answer to your original question "did I just fry my motherboard" appears to be "yes". Like Ed suggests, I think you fried a single power MOSFET. The RAMBo has exactly 5 ...

Turns out CRC mismatch is a S3D warning, and was not repeated.

I reloaded Marlin (after compiling out the SD card just to avoid that error). Still the same problem ---Tool 0 heater is constantly on even though the software thinks it is off.

Finally have time to start looking into this. All fuses verified, and I rechecked that there are no short circuits in the extruder. Connecting the printer to S3D I get two errors. One is "SD init fail" which is ok since I had to remove the RAMBO cover with the SD-reader. The second is that a reply t...

Regarding your question - I connected both plugs. I don't think you can connect the thermoresister the wrong way - these plugs (the ones with the clip that locks them) are designed so that you cannot do that. They don't even have to have the clip---thermistors and heaters can be plugged in either w...

Regardless, it's almost certainly a hardware problem. The firmware is on the digital part of the controller board which runs on its own power supply at 5V (or maybe 3.3V). It's relatively well-protected from things that go wrong with the high-voltage analog parts. It sounds like the heater cartridg...

jsc wrote:Maybe a thermistor issue?

Explain?

Hi Tim, I found two small (tinyfuse) fuses. Replacing them returned my printer to life. BUT,... as I was checking it, I noticed that one head (the one I was fiddling with when this happened) started to heat up. Before I could connect to the printer to see what it was doing, the fuse burned. Went thr...