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(a) Click on the second "Input Signal Select" box. You will see a
pull-down menu as shown in Figure 137, which gives a selection
of BITE ON (internal video signal) or BITE OFF (video channel 2
input).
PULL-DOWN MENU FOR MODULATOR CHANNEL 2 INPUT SELECTION
Figure 137
(b) Click on the "BITE ON" or "BITE OFF" of the pull-down menu. You
will hear a click (A8RL501) if the UUT operates correctly.
NOTE: The initial default selection is "BITE OFF". Selection of
"BITE OFF" also occurs at the end of the adjustment mode.
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(7) End of Adjustment Mode
Stop the adjustment mode and prepare the test setup for functional
testing as follows:
(a) Click on the "USER CONFIG" button if it is necessary to set the
user configuration on the UUT.
NOTE: If you do not click on the "USER CONFIG" button, the
frequency and input impedance values shown on the
"ADJUSTMENT MODE" window will become the user
configuration data of the UUT.
(b) Make sure that the frequency boxes show the user configuration
data for channels 1 thru 12, then click on the "END" button.
You will see the "POWER OFF" box (Figure 116B).
(c) Make sure that the RS232-RS485 selector switch is set to RS232,
then click on the "OK" button. You will see the "CONTINUE-END
SELECTION" box (Figure 116C).
(d) Click on the "CONTINUE" button. You will see the "LOG-IN"
dialog box (Figure 113) again with the "NEXT" button enabled.
(e) Put the test setup to the initial condition as follows:
Impedance Selector
SWITCH POSITION
Impedance selector 50W
VMU Tester
· The BNC Tee Adapter T1 (video signal source) is connected to
the VIDEO INPUT CH1 connector.
· The RFC1 cable (spectrum analyzer) is connected to the RF
OUTPUT RF1 connector.
· A BNC 50-W terminator is connected to each of the RF OUTPUT
RF2, RF3 and RF4 connectors.
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Oscilloscope
The VC4 cable (CH1 input) is connected to the BNC tee adapter
T1.
VMU Tuner
DISPLAY VALUE
CH 01
FREQ 151.25
(f) Go to step (3) of "A. Start of Tester Program, 4. Functional
Testing".
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PART NUMBER RD-AA5002 SERIES
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C. General Instructions for Fault Isolation
(1) DO NOT USE THE OSCILLOSCOPE FOR FAULT ISOLATION ON THE T1 AND T2
PRIMARY AND SECONDARY CIRCUITS. USE A DMM OR VOM FOR VOLTAGE
MEASUREMENTS ON THESE CIRCUITS.
The case and ground terminals of the oscilloscope are usually
grounded. If you touch the T1 or T2 primary circuit with the ground
clip of the oscilloscope, a primary short-circuit fault can occur.
The signal ground of the UUT connects to the chassis ground. If you
touch one of the T1 or T2 secondary windings with the ground clip of
the oscilloscope, a secondary short-circuit fault can occur.
(2) Use the oscilloscope to measure the DC and AC voltages and to
monitor the signal waveforms on the A1 thru A8 cards. The probe of
the oscilloscope must have a sharp point to go through the layer of
insulating compound.
(3) Signal Ground for Oscilloscope
The signal ground of the UUT connects to the chassis ground through
the A4 card and J1 connector. You can use a bare metal part of the
UUT as the signal ground for the oscilloscope
(4) Refer to "D. Fault Isolation Data" to find the possible problem area
and/or fault isolation procedure.
(5) Card Identification
For the printed circuit card assemblies installed in the UUT, we use
their designations only as their names. Refer to the table below.
DESIGNATION FULL NAME
A1 card CPU card assembly
A2 card Modulator card assembly
A3 card RF power card assembly
A4 card Power card assembly
A5 card Mother card assembly
A6 card Fuse card assembly
A7 card Connector card assembly
A8 card Video signal generator card assembly
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PART NUMBER RD-AA5002 SERIES
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There are twelve A2 cards installed in the UUT. Refer to (6) below
for their special identification.
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COMPONENT MAINTENANCE MANUAL Video Modulator Unit (VMU)(74)
