RELEASED: 10/2/2006
Page 34
COMMUNICATI0NS
HSD SERIES OPERATION AND MAINTENANCE
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VSWR overload latch circuit, as was described above, may be reset by depressing
switch S2 or by a command from the remote control board.
The Control Board uses +5 volt regulator U14 to provide a stable voltage supply to
the circuits on the Control board and to the Display Board.
J12 provides 12VDC for the cooling fans in the up-converter.
Finally, the J4 connector provides an interface to the up-converter power supply
pro/- 12VDC. The -12 volt input from the up-converter power supply on J4
pins 3 and 4 is bussed out to the power amplifier modules on J1 pins 14-17 and J2
pins 14-17. The -12 volt is also fed through J10-1 to the metering circuit on the
Display Board, through J9-9 to the 1
st
IF module, through J11-13 to the Remote
Control board, and through J7-2 to the Driver Amplifier. The +12 Volt input provides
all of the positive voltage requirements for the up-converter.
3.7 Display Board:
P/N 50527000
Schematic Diagram 50527002A, D1PC1
The Display Board contains the LED status indicators, the meter display circuit, and
the switches for Operate/Standby and AGC. Status inputs from the control board
are connected thru J1 pins 7-12 to the LED circuits. J1 also connects the switches
out to the control board.
The Operate/Standby indicator (DS4), a bi-color LED, works as follows. When the
unit is in Standby mode, there is a low (coming from the control board) on the gate
of Q4, making the drain high (open) thereby causing both the red and green LED
segments of DR4 to turn on which causes the LED to glow yellow. When the Q4
control board input goes high in Operate mode this causes a low on the drain of
switching FET Q4 turning off the red segment of DS4, resulting in a green indication
for the Operate mode.
The circuits for DS1, DS2, DS3, DS5, DS6, and DS7 are the same. When the
control board input status is high this causes a high on the gate of the associated
active device for the display LED. This in turn causes the drain of the device to go
low, grounding the cathode of the LED and turning the LED on.
There are two switch circuits on the display board. Switch S1 controls the AGC
on/off function, and toggles to ground for AGC on. The second switch (S2) controls
the Operate/Standby function and this switch toggles to ground for Standby. The
switch outputs are connected through J1 pins 13 and 14 back to the control board.
Both switches are the push/push type.
