York 00497VIP manual Power Supply, Refer To Fig, Service

Service

POWER SUPPLY

(REFER TO FIG 47)

The Power Supply provides the DC power for the LCD Display and all the printed circuit boards in the Control Center. It receives a 100 to 250VAC input from an external power source and provides the following DC outputs:

•+12VDC

•+5VDC

•Ground

The +12VDC, Gnd and +5VDC outputs are applied to the Microboard. There, these voltages are applied to the circuits requiring the respective voltage. From the Microboard, the +12VDC and +5VDC are distributed to other system components requiring these voltages. These include the MicroGateway, LCD Display and Display Backlight Inverter Board.

As shown in Fig. 47, the Microboard contains two voltage regulators that create separate +5VDC and +3.3VDC supplies. The +5VDC supply is dedicated to all the Microboard Analog circuits and is labeled

as the +5VDC (Analog) supply. It is also routed to all Temperature Thermistors. This permits all Analog circuits to be powered by the same supply, eliminating any offsets caused by voltage regulator drift. The +3.3VDC supply is utilized by the Microprocessor, Flash Memory Card and other digital circuits. It could also be applied to the Backlight Inverter Board, depending on the Display manufacturer’s requirements as explained next.

Different Display manufacturers can require different supply voltages for their display and supporting circuits. To accommodate the different Display manufacturer’s voltage requirements, Microboard Program Jumpers JP2 and JP5 must be positioned to provide the required supply voltages to the Display and the Display Backlight Inverter Board. Either +5VDC or +3.3VDC, as determined by JP2, is applied to the Display. Either +12VDC or +5VDC, as determined by JP5, is applied to the Display Backlight Inverter Board. Refer to Table 2 “Microboard Program Jumpers”.

94 YORK INTERNATIONAL