hotbed/extruder is not heated up(GT2560/GTM32/sanguinololu)
http://www.geeetech.com/forum/viewtopic ... 13&t=17117
If your hotbed or extruder is not heated up(GT2560/GTM32), please refer to the informations below to check it:
1. Check the temperature first
If it shows “room temperature/0, room temperature/0”,Both extruder thermistor and hot bed thermistor are good. If either or none of them is room temperature, then the thermistor is bad contact. If one of them is good, you can swap them to see if the other one is dead or not.
2 Check the board is working or not
2.1 Check the board power
With the board powered on, the lower left LED lights will light up. If not, then check the fuse on the board. You can measure the voltage of the two sides of the fuse, if there is a big difference then the fuse is dead.
For GT2560, board power usually is 12V, and 5V for the mainchip. For GTM32 on M201, main power is 24V and 3.3V for mianchip.
2.2 Check the mosfet
Manually heat up the hotbed and extruders, if the LED lights under the hotbed and extruder slots all lighted up, then the mosfet that controls the heating is good. If not, the mosfet might be dead. You can check the mosfet as follows:
For GT2560, use the multimeter to measure the voltage between pin 2 and pin 3 of the mosfet, when heated up it is 0V,and when not it is 12V. The type of fuse and mosfet are as follows:
name specific type parameter
fuse SMT 5*10 0154010.DRT 10A/125V
fuse SMT 5*10 0154015.DRT 15A/125V
mosfet TO-220 STP55NF06LTO
For GTM32, measure the voltage between the pin1 and any of the other pins(GND), when heated up it is 0V and when not it is 24V. 2.3 Check the resistance of the heating cartridge and hotbed
Measure the resistance of the heating cartridge and hotbed.
The resistance of the hotbed ranges from 1-2ohms. When shorted out it is less than 1ohms and when open circuit it is infinite.
The resistance of the heating cartridge is about 3.6ohms. Also when shorted out it is less than 2ohms and when open circuit it is infinite. If there is a short circuit or open circuit, check the wiring or the component itself. You can also use a good one to verify it. Measure the resistance as follows.
Note: For GTM32, cause the mainpower is 24V, so the resistance of the heatbed should be about 5ohms and 12.1ohms for the heating cartridge.
Measure the resistance of heater.
1)unplug heating wire from mainboard.
2)turn the multimeter to Ω.
3)put the red probe of multimeter on one end of heating wire ,put black probe on another end.please let probe tips touch metal carbonyl conducting layer inside insulation material. Measure the resistance of hotbed.
3. When heating up the hotbed, the temp cannot reach 85℃ or it takes a long time to reach 100℃
Generally, the hotbed can be heated up to 70 ℃ in about 2-3mins, and it takes about 40mins to reach to the preset temperature. This is because compared to hotend, the hot bed area is too big and dissipates quickly, while a fan or air conditioner will also enhance the heat dissipation. The role of the hot bed is to keep the printings from bending. If you use ABS, with a temperature of 75-85 degrees and use some sprays on the hotbed, you’ll also get it work.