Chapter 2—Functional Descriptions2–8 Model 330, 340SC, and 370SC Service Manual2. +24V Standby and Arc Lamp power supplies turn on.3. When Arc Lamp lights (run voltage sensed by a window comparator in theSPS), SPS pulls /LAMPLIT line low.4. SCB senses /LAMPLIT low and awaits further instructions.Electronics only power-up:1. Upon receipt of Electronics-On command, SCB pulls /FANENBL and/LVPSNBL lines low.2. +24V Standby and Low voltage supplies turn on.3. SCB senses +5V supply at correct level and enters normal programsequence, lamp can be turned on at any time.Table 2-1 System Power Supply Voltage DistributionVoltageFanHVPS CRT SCB HDB VDB VPB RTG VABArcLamp/Ignitor+5v+5v Stb+6.3v+15v-15v+24v+24v Stb+48v+107v+170v
