HP 3455A - Page 144

Section
VIII SERVICE
GROUP B
Model 3455A
b. If unable to repair the Auto-Cal failure,
Table
8-8-6
may be helpful
if applicable. The dc in-
operative section paragraph
8-B-18
in
this service group may also be
helpful.
8 B-1B. DC
Inoperative (Schematic 1).
8-B-I9.
When
the dc
function of thO 34SSA is
inoperative,
it can also
show
up as
an Auto-Cal
failure.
These failures should be
serviced
using the information
in paragraph 8-B-3 to 8-B-lS in this
service group. Some of dc and Auto-Cal
failures may be serviced by using the
following procedures.
Table 8-B-7. Possible Aute-Cal Failure Causes.
Cal Constants Failed
3455A Display Possible Cause
13 12 1
1
10 9 8 7 6 5
4
3 2
1 Shorted A14U1d
12 10 5 4 3 0
.0757 Open A1 4C2
12 9 5
4 3 A10Q36
Shorted
1
1
10 9 8 7 6 5
4
3 2
1
0
.0007 Gate Bias
1
1
10 9 8 7 6 5
4
3
2 1 0 .0000 DC
Pre-amp
1
1
10 9 8
7
6 5
4 3 2 1 0 .0074 DC
Pre-amp
11 9 8
7 6 5 4 3 2 1 0
9.8438 A10Q4 Shorted
1
1
10 7 6
.0000 A10Q19 Open
1
1
9
8 3 2
A10U3
10 9 5 3
9.7650 A 10Q 16 Shorted
10
5 0 .0000
A14Q3 Open
10 9 3 0
A10Q15 Shorted
10 6 5
1 0 A10Q18
Shorted
10 9
5 0 9.5703
A10Q2 Shorted
10
2.5026 A10Q4 Open
10
9
8 3 2
A10Q21 Shorted
A 1002 Open
9 7 6 5 4 3 1 0
A10U18 or A10037
9 7 6 5
4
3
1
0
Reference
Supply
9 7 6 5
4
3
2 1 0
A
1002 9
and/or A 10031 Shorted
9
5 3 0
A 1003 9 Shorted
9 3
A10U3 or Open A100A18
9 3
0 A10035
Shorted
9
A10Q27 Open
9
8 5
4 2 1 0
A10027 Open
A 10021
Open
7
5
4 0 A
1002 7 Shorted
7 5 4
A10O15 Open
7
6
4
1 0
A10Q3 Shorted or A10K5 Open
A10O16 Open
5
4 0 A10Q28
Shorted
5 0
A 1 002 2 or
A
1
00
1 9
Shorted
5
A10035 or A10K6 Open
5
6.7542
A 1 0033
Open or A
1 0038
Shorted
A14 Board or A10034 Shorted
X.XXXX
Where X is any number
go
to Service
Group 6
B-6-20.
Leakage and Other Various
Malfunctions.
8-B-21.
The following quick leakage test may be used to isolate most
leakage failures.
a.
Set the 3455A to the
DCV
function 10
V
range,
with Auto-Cal off.
b. Short and then
open the input terminals of the instrument and note the change
in readings on
the display.
8-54