HP 85108, System Manual

Page: 111 / 136

b1 IF Signal P ath Check
Step Connections/setup Conclusion
(if the problem is corrected)
1 Sw ap cables W50 & W51. If the problem w as in the ref. (a1 & a2)
path, replace W50. If the problem w as
in the test (b1 & b2) path, replace W51.
2 Mo v e W51 on A2J2 to A2J6.
Mo v e W50 on A2J6 to A2J2.
Mo v e W54 on A16J1 to A16J3.
Mo v e W47 on A16J3 to A16J1.
Mo v e W43 on A16J2 to A16J4.
Mo v e W48 on A16J4 to A16J2.
Go to step 3.
3 Do this step only if the problem w as
corrected in step 2.
Sw ap cables W47 & W54.
Sw ap cables W48 & W43.
If the problem w as in the ref. (a1 & a2) path,
determine whic h cable is bad (W43 or W54) and replace it.
IF the problem w as in the test (b1 & b2) path,
determine whic h cable is bad (W47 or W48) and replace it.
4 Sw ap cables W5 & W49. If the problem w as in the ref.
(a1 & a2) path, replace W5.
If the problem w as in the test
(b1 & b2) path, replace W49.
5 Put in a kno wn go o d A16 b oard. replace A16.
6 Put in a kno wn go o d A17 b oard. replace A17.
7 Return to the pulsed-RF troublesho oting o w c hart.
Procedure 5: A6 Clock 20 MHz Output Check
1. Disconnect the cable W5 or W54 at A6J9 or J8 and connect an oscilloscop e to A6J8 or J9.
The output should t ypically b e ab out 1.8 v olts p eak to p eak in to the 1 M oscilloscop e
input imp edance. The output v oltage drops to ab out 1.2 v olts p eak to p eak when
connected to the pulse detector via W5 or W54.
A6J7 connects to the 20 MHz output on the rear panel and pro vides the same signal lev el.
2. If the signal is missing or greatly diers b et w een J8, J9, and J7, replace the A6 Clo c k
b oard.
System Service and Troubleshooting 6-19