Just to clarify - if the gate voltage goes from 0 to 5 when the software is calling for heat, that means the rest of the electronics are ok and the MOSFET is bad? I have the same problem with my hot end (likely caused by a short in the wiring, now fixed). Do you have a link to how to measure the MOSFET gate voltage? I am going to search for that piece of info now.by RetreadNJ - General
You were right - the resistor was shorted to the nozzle. I insulated the leads, but there must be a flaw in the insulation. I'll take it apart shortly. And yes, the first resistor, now uninstalled, is fine. Thanks!by RetreadNJ - Reprappers
Update: the power resistor didn't fail short. My wiring was faulty so that the resistor leads were shorting out on the nozzle.by RetreadNJ - Reprappers
When my hot end didn't heat up, discovered that the power resistor was a short. Replaced it today and the new one, which I measured at 5.8 Ohms before installing it, shorted out. Does anyone know what could be causing this? If I disconnect the resistor leads then turn on the RAMPS 1.4, I measure 12 V across the hot end terminal. Printer is Prusa Mendel i2 with a J-Head hot end. I would reallyby RetreadNJ - Reprappers
We are newbies and learning as we go. Last week, we finally got all the motors working (x,y,z and extruder). Then on Sunday, after troubleshooting some jitters in the z-axis movement (changing the max feed rate to 1 etc) ALL the motors stopped responding. It sounded like a software problem, so we reinstalled all the software and firmware. Still no instructions to the motors to move. In pronterfacby RetreadNJ - Reprappers
Thank you all very much! I'm getting a replacement of the correct part from the seller. (My nozzle does not appear to have a large enough hole for a cartridge heater.)by RetreadNJ - Reprappers
I am building the Prusa Mendel i2 and it's almost complete, but yesterday when I turned on the heat to the J-Head nozzle for the first time, it didn't heat at all. I measured the resistance and it is close to a short (0.3 Ohms - the spec is 5.6 Ohms or 6.8 Ohms). I ordered a new power resistor but it won't come for over a week. My year-long senior project is due, and I have to present it to the eby RetreadNJ - Reprappers