2. Service
Assembly/Module Diagnostic Trees (Diagnostic Section 3)
116
A18 Diagnostic Tree
(A/M Subsection 8)
This subsection describes the A18 9.2 GHz PLL Module diagnostic tree.
3.8.1.0 A18 Module Power Check
1
Check the +12V, -12V, and +5V terminals on A18 with a DMM.
2
12V is b12 and +12.5V to chassis.
3
5V is between 5.25 and 5.5V to chassis.
4
Verify -12V is between -12V and -12.5V to chassis.
QUESTION:
Are power supply voltages correct?
If Yes:
Go to, 3.8.2.0.
If No:
Go to, 2.1.1.1.0 (Power-supply diagnostic tree).
3.8.2.0 A5 87.368230 MHz Input Signal Test
1
Disconnect coax cable from A18J1.
2
Connect free end of coax to the 50
Ω
input of an oscilloscope.
(If a 50
Ω
input is absent, use the high-impedance input with a
50
Ω
coaxial-feedthrough terminator at the scope end of the coax).
3
Verify the presence of an ~87 MHz sine wave with at least 0.4 Vp-p
amplitude.
4
Reconnect free end of coax to frequency counter input and verify that
signal frequency is 87.368
±
1 kHz.
5
Reconnect cable to A18J1.
QUESTION:
Does the signal comply with the characteristics
described in step 3 and 4?
If Yes:
Go to, 3.8.3.0.
If No:
Go to, 3.8.2.1.
Summary of Contents for 5071A
Page 2: ......
Page 40: ...1 Performance Tests Verifying Specifications 5071A Complete Performance Tests 24 ...
Page 48: ...2 Service Pre Troubleshooting Information 32 Figure 2 1 Instrument Top View ...
Page 168: ...3 Theory of Operation Functional Block Descriptions 152 Figure 3 5 Power Supply Block Diagram ...
Page 173: ......
Page 194: ...5 Replaceable Parts How To Order A Part 178 ...
Page 197: ......