HP 8133A Service Manual page 136

7-4 Theory of
Operation
Power Control Board
This board contains the regulators. The power main board supplies
this board with:
The control power + U B
The voltage and current sensing signals.
It is responsible for
:
Generating the required reference voltages and gate control signals.
This enables the power main board to carry out voltage regulation
(with foldback current limiting) and selection of secondary winding
taps.
Supplying the reference current for the fan control circuit on the
power main board.
Power Outputs
The power supply provides the following outputs:
-4.5 V, 3.5 A
-5.1 V, 2.5 A
A
-15 1.1 A
+15 V, 1 . 8 A
fan( +) & (-)voltages
HPSV (High Power Supply Valid): This is a signal for the
Microprocessor indicating that the Power Supply is stable (Power
Fail Detection)
0.05 mA at + 5 . 1
4.85 V
4.85
V V