Microprocessor Troubleshooting; Data Bus Lines Troubleshooting - HP 3456A Operating And Service Manual

Service
mended integrated circuit(s) in the given order. Replace
the one on the left first and then replace the one next to
it, if the signature was stit! bad.
NOTE
Re /er to Section V II ( Backdating) 0 / this
manual/or the signatures in steps h, j, m,
0,
and I f the 3456A is equipped with ROMs
having part numbers 18/8-1367 , 1818-1368,
and 1818-1369/ or A4U5, A4U7, and A4U8,
respectively. ROMs with these numbers may
be installed for instruments with serial
numbers 2015A-03070 and below.
I.C. Pin #
Signature
AJU4 1 1 1 1 80
A3U4 10 0000
AJU4 1 2 1 1 80
A3UI4 1 5 1 1 80
AJUI2 J 892F
A3UI2 5 P26J
1 1
AJUI2 1J02
AJUI2 1 4 8547
A3UI2
I J 8547
A3U7 3 COlA
AJU7 5 C532
A3U7 1 1 HA6P
A3U7 14 2A22
A3U7 I J 2A22
A3U8 3
2A22
A3UI4 IJ 8547
i. Plug the HP-IB SA Module I (-hp- Part No.
5061-1 153) into the 3456A's rear HP-IS Connector. Do
nOt remove Module IJ.
j . Check the following signatures and if any are bad,
replace the recommended Integrated Circuit in the given
order:
I.C. Pin # Signature
AJU8 5 FFSA
A3U8 1 1 421U
A3U8 I J 3501
AJU8 6 FF8A
A3U8 10 421U
A3U8 14 3501
A3UI4 2 FF8A
A3UI4 6 421U
A3UI4 10 3501
k. Turn the 3456A Off and remove both HP-IS SA
Module I and Il.
I. Insert the HP-IB SA Module III (-hp- Part No.
5061 - 1 1 55) into the socket of A3U9 and turn the 3456A
On.
m. Check the following signatures and if any are
bad, replace the recommended Integrated Circuit in the
given order:
Replace
AJU4
AJU4,U8
A3U12,U7,U8,U4
AJUI4
AJUI2
AJUI2
A3UI2
AJUI2,UI4
A3UI2
A3U7
A3U7
AJU7
A3U7,U8
AJU7
AJU8
AJUI4
Replace
A3U8,UI4
A3U8,UI4
A3U8,UI4
AJU8
A3U8
A3U8
AJUI4
A3UI4
A3UI4
I.C. Pin # Signature
0000
A3U4 10 1 1 80
1 2
A3U4
1 5
A3U8 1 1 80
A3U8 5 892F
A3U8 1 1 P26J
A3U8 I J 1J02
A3UI4 1 3 8547
n. Plug the HP-IB SA Module I (-hp- Part No.
5061-1 153) into the 3456A's rear HP-IB Connector. Do
not remove Module Ill.
o. Check the following signatures and if any are bad,
replace the recommended Integrated Circuit in the give
order:
I.C.
Pin # Signature
AJUI2 3 892F
A3UI2 5 P263
AJUI2 1 1 1J02
A3UI2 1 3 8547
A3UI2 2 892F
A3UI2 6 P26J
A3UI2 10 1J02
A3UI2 14 8547
A3U7 2 892F
A3U7 6 P263
A3U7 1 0 1302
A3U7 1 4 8547
A3U8 2 8547
I
p. Remove Modules and
good, replace A3U9.
8·A·27. MICROPROCESSOR TROUBLESHOOTING.
8-A-2S. If the processor is presumed bad, try the
following before replacing it:
a. Make sure the PSR (Power Supply Ready) is high.
Replace A3UIS if incorrect .
b. Make sure the RST line is high. If the line is low,
replace A4U14. If the line is high and UI4 is suspected
of being bad, temporarily short the processor's pin
ground. When the short is removed, the pin should go
high and turn on the processor. Replace U 14 if it hap­
pens.
c. Make sure the NMI line (A4U15 pin 6) is high.
This line can be held low by the HP-IB chip (A3U9).
Remove A3U9 and try again.
d. Make sure the IRQ line (A4U 1 5 pin 4) is not held
low. A low line shows up as a Display failure.
8·A·29. DATA BUS LINES TROUBLESHOOTING.
8-A-30. Bad signatures on Data Lines DO to 07 with
Address Lines AO to A l 5 good, can be caused by many
different circuits. To help isolate the circuits, the
Model 3456A
Replace
A3U4,U8
AJUI2,U7,U8,U4
A3U8
A3U8
A3U8
AJU8
A3UI4
Replace
A3U12,U7
A3U12,U7
A3UI2,U7
A3UI2,U7,U8
AJUI2
A3UI2
A3UI2
A3UI2
A3U7
AJU7
A3U7
A3U7
A3U8
Ill. If all the signatures are
40
to
-