Note

Because the Cal Oscillator circuitry on the A4 assembly is such an integral

 

part of the IF adjustment, always check this assembly first, before checking

 

the rest of the IF Section. A faulty Cal Oscillator can cause many apparent

 

“faults” in the rest of the IF Section.

 

 

Troubleshooting Using the TAM

When using Automatic Fault Isolation, the TAM indicates suspected circuits that need to be manually checked. Use Table 8-l to locate the manual procedure.

Table 8-2 lists assembly test connectors associated with each Manual Probe Troubleshooting test. Figure 8-l illustrates the location of A4 and A5 test connectors. Figure 8-2 illustrates the levels and paths through the IF Section.

Note

HP 85629B Test and Adjustment Modules with firmware revisions A through

 

F cannot make valid measurements on test connectors A4J9, A4J10, or A4Jll.

 

 

 

 

 

A 5 I F

A 4 L O G A M P

39

 

 

 

 

 

/Jg

 

 

 

 

 

37

J5

 

 

 

 

 

JIO

J5

 

 

 

 

 

 

J8

 

 

 

(REVISION

 

 

 

(REVISION

 

 

 

 

C O N N E C T O R

 

C O N N E C T O R

 

 

 

 

 

 

 

 

 

 

37

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Jll

34

 

 

 

 

 

 

J6

J4

 

 

 

 

J3

 

 

 

 

J3 /

 

 

 

 

 

 

 

S K 1 7 0

Figure 8-1. A4 and A5 Test Connectors

IF Section 8-3