HP 3562A Service Manual page 464

S E RV I C E
4. To verify the device decoder PAL and buffer, use a logic probe to check the fol lowing
s ignals are the correct TTL leve l :
U303 p i n
5 . Press the H P 3562A keys a s fo l lows:
R E T U RN . . . . . . LOOP
6. Use a logic probe to verify the fol lowing signals are the correct TTL leve l :
U303 p i n
7 . U s e a l og i c to verify the D S data l i nes are togging ( F R E N D I NT F C E i n loop mo de).
Some of the l i nes w i l l toggle s l owly. Use the fol lowing test locations:
U406 p i n s 1 and 11 through 1 9
U405 p i n s 1 1 through 1 8
8. Press A2 S1 . After the powe r-u p tests are com plete, verify the fol lowing s ignals are
the correct TTL leve l :
Test lo cation
U203-2
U304-6
U304-9
U302-4
9. I f the fault has not been found, go to part E.
8-1 4
1 2 Togg l i n g
U401
1 3 Togg l i n g
1 4 Toggl ing
1 5 Togg l i n g
1 6 Togg l i n g
1 7 H igh
1 8 Togg l i n g
1 9 Togg l i ng
O F F
LOOP
ON
1 2 H igh
1 3 Togg l i n g
1 4 H igh
1 5 H igh
1 6 Togg l i n g
1 7 Togg l i n g
1 8 Togg l i n g
1 9 Toggl i n g
Signal Name
T E ST
N RSTL
BRST
R E S E T L
p i n 2 Togg l i n g
Togg l i n g
7
1 0 Togg l i ng
1 1 Togg l i n g
T E S T
S O U R C E
TT l leve l
Low
H igh
H i gh
H igh
MO D E L 3562A
FR E N D
I N TFCE