Service manual

64 Principles Of Operation
Output Circuits
The output circuits include the following circuits:
• Chassis mounted components.
• Two power transformers, T900/T901.
• Two inductors, L900/L901.
• Two rectifiers, D900/D901.
• Output capacitors.
• A7 Snubber board mounted to the heat sink.
• A8 Fast Sense board.
• A9 Slow/Downprogrammer board and output bus bars.
Each combination of power transformers, T900/T901, and rectifiers, D900/D901, couples the output pulses from the A3
FET board. The output of each transformer/rectifier combination is connected in parallel before being applied to the output
filter. The output filter assembly consists of bus bars with the filter capacitors bolted to them. The filter chokes, L902
through L906, consist of ferrite cores enclosing the bus bar. The current-sense resistor, R900, is part of the positive-output
bus bar.
RFI
FILTER
LOWER
1
2
3
AC INPUT
BOARD
DC RAIL
BOARD
+RAIL
-RAIL
FET
BOARD
P/O SNUBBER
BOARD
P/O SNUBBER
BOARD
FAST
SENSE
SLOW SENSE
DOWN PROG
R900
BIAS
BOARD
ON\OFF
DISPLAY
KEY PAD
FRONT PANEL
BOARD
FRONT
PANEL
ASSY
UPPER
FRONT
PANEL
ASSY
GPIB
BOARD
GPIB
CONTROLLER
SERIAL
DIGITAL
CONTROL
LINK
+24V
AUX BIAS
TRANS.
T900
T901
FAN
SECONDARY
INTERFACE
CT/CC
CONTROL
SWITCHING
DP
CIRCUITS
CONTROL
CONTROL BOARD
+S
-S
Vp
Ip
I
MON
Figure 4-3. Agilent Series 669xA Power Supply, Block Diagram