Is your nozzle(s)/hot end not heating up? Below are a couple steps for diagnosing the issue.
Hot End: Assembly that moves in the XY direction and melts the filament
Nozzle: Small metal cylindrical disk at the bottom of the hot end
Heating Element: Small aluminum block that is just above the nozzle
Resistor: Heater of the hot end, runs through the heating element
Thermistor: Temperature read out for the hot end, runs through the heating element
Fuse: a sacrificial device to provide overcurrent protection (if too much current is run through the fuse, it will blow instead of damaging the printer, then the fuse can be replaced, rather than the hot end, heat bed, motors, etc.)
Replacement Fuse: Here is the link for a replacement fuse
1) Turn the printer on. Use the LCD screen or programs to move the printer X, Y, Z to verify that the motors are working correctly.
2) Check the temperature read out for the nozzle. It should read somewhere around room temperature (25-30C). If the nozzle temperature reads 5C, then that means that there is an issue with the thermistor. The thermistor in the hot end may have been permanently damaged. If the temperature reads 5C please open a Tech Ticket and let us know that you got to step 2. If the temperature reads 0C and/or the screens reads a "Min Temp" error then that means that a thermistor is not plugged in to the RAMBo circuit board. To access the RAMBo circuit board, remove the back panel by unscrewing the six M6 screws in the corners of the panels. The picture below displays the thermistors (Nozzle1 = Gray/Purple, Nozzle2 = Orange/Yellow) . NOTE: If the printer is single head, the printer will only have the gray and purple wires. Also, if you are upgrading to the JR2x Dual hot end, both thermistors will need to be plugged in correctly for the hot end to work properly. If not, it should read a "Min Temp" error.
3) Use the VIKI LCD screen or the computer software to preheat the nozzle(s)/hot end to 240C. In the VIKI, use "Control > Temperature > Nozzle". When the LCD screen returns to the home screen, the nozzle temperature should read ##/240C.
4) After about 3-5 minutes, the nozzle temperature should be right around 240C. If the nozzle is just sitting around room temperature (25-30C), then your printer may have a blown fuse. But the first thing to check is the power supply.
5) Checking the power supply: If you have a v2 printer, remove the back panel by unscrewing the six M6 screws and set them aside. If you have a v1 printer, remove the screws, but be careful of the wiring because it runs through the back panel. Use the "HD v1 or v2?" solution to determine whether the printer is a v1 or v2. Turn the printer on with the power switch. There is a green LED light on the bottom right hand corner of the power supply. With the printer on, the LED light should be on. A picture of the light on the power supply is below. If the green LED light is NOT on, please open a Tech Ticket and let us know that you got to step 5. The power supply or power input fuse may need to be replaced.
6) Checking the fuses: Below is a diagram of the RAMBo circuit board. Note that there are 2 identical fuses, one of the nozzle heater, one for the motors. Turn the printer off. With a pair of needle nose pliers, switch the two identical fuses. Next, turn the printer back on and move the printer X, Y, Z. If the printer doesn't move X, Y, Z, then a fuse needs to be replaced. If the printer moves correctly, then you know that both fuses are good. Then try heating the nozzle to 240C like in step 3. If the nozzle still does not heat up correctly, please open a Tech Ticket and let us know that you got to step 6.
Please open a Tech Ticket if you have any questions or need assistance with this process.