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3-7. PROMPT VIDEO Cable Compensation System Adjustment
3-7-3. RX PROMPT VIDEO Demod. Adjustment
Rank:
C
Note:
Perform the adjustment only when
replacing 1LV2 (PROMPT RX
FREQ) or 1LV3 (PROMPT RX
TUNE)/DM-94 board.
When adjusting this step, the length
of triaxial cable is required less than
500 m.
Adjustment of BVP-700/700P must
be completed.
Equipment:
Oscilloscope, Video signal generator
(SWEEP, 10 STEP signal)
To be extended:
DM-94 board
Preparation
• S4 (CCU → CAM/CAM → CCU)/
MD-83 board (BVP side) → "CAM → CCU"
• Remove the green harness of MPX filter from CN35
(PROMPT) connector on DM-97 board (BVP side).
And connect its harness to CN27 (PROMPT
REVERSE)/MB-430 board (BVP side).
• S5 (TX← → RX)/
DM-94 board (CCU-700A/700AP) → "RX"
• S6 (TX← → RX)/
DM-94 board (CCU-700A/700AP) → "RX"
• S1 (MODE AUTO/MAN)/
DM-94 board (CCU-700A/700AP) → "AUTO"
• Feed the SWEEP signal from the video signal generator
to PROMPTER connector (CCU rear panel).
Test point:
pin D34 (GND: pin C34)/
1LV2 (PROMPT FREQ)/
Adjusting point:
1LV3 (PROMPT RX TUNE)/
Adjustment Procedure
1. Observe the waveform monitor screen and adjust
1LV3 (PROMPT RX TUNE)/DM-94 board so that
the video waveform is appeared.
2. Adjust 1LV2 (PROMPT FREQ)/DM-94 board so that
the frequency response at 6 MHz portion is minimum.
3-36
extension board
DM-94 board
DM-94 board
6MHz
3. Change the output signal of the video signal generator
to 10 STEP signal.
4. Re-adjust 1LV3 (PROMPT TUNE)/DM-94 board so
that the "A" portion at video waveform is flat.
(Note:If not met, Re-perform "3-7-3. RX PROMPT
VIDEO Demod. Adjustment" after performing "3-7-4.
RX PROMPT VIDEO RF AGC Adjustment".)
A
Note: After the adjustment, set the switches as follows.
• S4 (CCU → CAM/CAM → CCU) switch/
MD-83 board (BVP side) → "CCU → CAM"
• Return the green harness of MPX filter to CN35
(PROMPT) connector on DM-97 board (BVP side).
• S5 (TX← → RX) switch/DM-94 board → "TX"
• S6 (TX← → RX) switch/DM-94 board → "TX"
• Remove the BNC cable from the PROMPTER
connector/CCU rear panel.
Flat
CCU-700A
CCU-700AP
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