2. Service
Top-Level Diagnostic Tree (Diagnostic Section 1)
46
1.1.3 Tube PROM Test
1 Remove power from the instrument.
2 Disconnect A2P3 from A2J2.
3 Apply power to the instrument.
4 Verify presence of +5 V (
±
0.5) at pin 1 on A2J2 to chassis
ground.
5 Use a digital storage scope or logic analyzer (trigger set to 2.5V,
DC coupled, timebase to 50 us/div., no auto trigger) to verify the
signals are toggling at A2J2 pins 2 and 3 following activation of
the reset button on top of A3. The pulse levels should be
approximately 4.0 Vp-p. (Refer to the A2 connector pinout
diagrams at the beginning of the A2 diagnostic trees opposite
procedure 3.1.1.1.0.)
QUESTION: Is there +5 V at pin 1 and a toggling signal present on
pins 2 and 3 of A2J2?
If Yes: CBT ROM may be defective: contact Symmetricom for assistance.
If No: Remove power, replace A2, and retest.
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: ......