Hello, I have been slowly building a printer with a custom frame of my own design, but reprap electronics (Sanguinololu 1.3a). For my hotend I am using a 5ohm wire wound resistor.
I got the electrical testing phase of the hotend, and it seemed to work fine the first time, I slowly bumped up the target temp in 25c increments up to 200c, then let it run for 20-30 minutes with no problems.
Later that night I just set the target temp to 200 right away, and my temp graph started climbing until it hit 175c in a minute or two, then started going down. I immediately powered down the whole thing and started feeling around to see if anything overheated or was on fire, at the moment everything on the Sanguinololu board seemed okay (not hot). So I plugged it all in again, but that time the heater would not turn on.
I also tried using the extra hotbed heater contacts to see if those work, but it does not give power either.
Three other weird things I noticed:
1.) When I attempt to turn the heater ON, the 5v regulator starts to heat up immediately, and within 20 seconds or so it is too hot to touch. (I'm pretty sure it did not do that before, and it's fine when the heater is OFF)
2.) When the heater is OFF I get 0.000v across the heater contacts, when the heater is ON I get 0.003v.
3.) When the heater is ON, the thermistor temp measurement jumps a few degrees, even though the heater never warms (no voltage).
I am sure I blew somthing out, but what I am not sure. I would probably just get a new set of all the parts, but I am also afraid my 5ohm heater may be to blame.
My electcrical engenering skills are pretty weak, and any insight would be appreciated!
