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6-25. X20 a JXS
Tsst
H i s test checks the circuits shown in the signal path in Figure 6-17. In particular, the X20
and X5 Amplifiers of channels A and B are tested. Hie same signal sources are used in this
test as were used in the previous test. An -hp- 3455A Multimeter is connected to the output
of each 50kHz Lowpass Fdter to check rolloffs. The voltmeter is connected to Channel A
and B Outputs to check for proper gain of the the amplifiers and the proper peaking in the
XS Amplifiers. The results of the test v e printed.
Initializing the Test
With the Low Frequency Menu displayed, press SFK K4 to initialize the test. After initializa
tion, follow the instructions displayed on the computer.
What if the Test Fails?
Assuming the previous tests have passed, the most likely cause of failure would be the 50kHz
Lowpass Fdter, the X20 Amplifier, or the X5 Amplifier of either channel. Isolation of the
failure should be straightforward because each test checks the operation of only one block.
Use "SWITCH" to check the operation of the switches. Refer to Service Group One for
schematics, component locators, and circuit descriptions.
SetUp
10 MHZ REFERENCE
D
O
35601
J
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rlo
OSCILLOSCOPE
□
C H A
C H B TRIG
tl
JW kHz Low Pass Filter Shape 10
-hp-JSHMChatmeJAandB
TP401 TP402
f
at
— s s= . — " " A - * - U
U
HsI
* # * - -
BUS, i f f ? ,- S3
Figure 617. X20 and X5 Amplifiers Test
X20 and X5 AmpUfiers Test
6-39
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