Liquefier Temperature Control The liquefier T/C connects to the controller board through the power distribution board. The T/C generates a variable low level current that depends on the temperature of the T/C. This analog signal from the T/C is amplified by the head distribution. It is then sent down the umbilical cable to the PDB, and then to the controller board. An A to D converter in the ColdFire chip converts the analog signal to digital. In order to improve temperature resolution, this signal is biased. The lowest reading possible is 109.5 ° C. The highest reading is 330 ° C. The liquefier temperature is maintained at: Model: 310 ° C, Support:
300 ° C Temperature control is accomplished using “pulse wide modulation” (Figure 3) . Figure 3: Pulse Width Modulation (PWM) Actual power to the liquefier heater is supplied by the PDB, which is controlled by the controller board. The head heaters are turned off and on 1000 times a second (pulses). The duration of the 120 VDC pulse determines the average power being supplied to keep the liquefier at temperature. Temperatures can be read using a volt meter at test points TP5 for model, and TP4 support on the PDB (10 mV per degree C). Actuators, Switches & Optical Sensors The input and output signals are passed through the PDB and then processed by the controller board.
The non-motor actuators on a uPrint system are 24 volt solenoids. The 24 volt power is supplied by the PDB which -9