5. Electronics
Figure 5-9. Switching Power Supply
• Switching Power Supply. This power supply rectifies and
filters the 120 VAC from the Isolation Power Transformer.
This board has an internal 3A/250 VAC fuse.
This power supply provides +5 VDC and ground for the digital
circuits, and +12 and -12 VDC and ground for the analog
signal conditioning circuits in all boards. Only the +5 and +12
VDC can be calibrated. (See Figure 5-9 for potentiometer
locations.) The +5 VDC should be calibrated to between +5.00
and +5.05 VDC. These voltages are fed directly to the
following boards (see Figure 5-10).
o Passive Backplane
o Peripheral Interface Board (this board distributes power
to the NIBP and PDC reader, see Figure 5-10)
o LCD
You may monitor these voltages easily using the UF-
Proportioning Power Board test points.
Note
The adjusting pots on the Switching Power Supply are extremely
sensitive, so make sure to turn them only very little every time.
157-1278-912 Rev A 5-13
November 2003
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