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8-320.
HP-IB
Interface Assembly
(AS
Board)
Troubleshooting
8-321.
At
Power-Up,
the
HP-IB interface
is
tested.
An
ERROR:
1/0
message will appear
on
the
display
if
the test
did
not
pass.
If
the
test
passes,
the
address
of
the interface
will
appear
on
the
display.
NOTE
If
all
the
switches
on
the DIP switch,
ASS1,
are
set
to
1 (open
or
upward) the
error
message
will
appear
on
the display.
8-322.
If
the
1/0
address diagnostic fails and
the
counter
passes
all
other
diagnostics, verify that
the
ribbon
cable
ASW1
is
properly
seated in its
mother-
board
connector
A 1]8.
8-323.
Verify
the
following
voltages
on
the
AS
board
assembly:
SIGNAL
NAME
TEST
POINT
RANGE
+S
volts
+S
volts cmc
+S
(TP1)
U2,
pin
24
±0.2 volts
±0.2 volts
8-324.
Verify
that
a
3.S
MHz
(nominal)
clock
signal
is
present at
US
pin
2.
8-32S.
A signature analysis
mode
is
available
for
the
AS
board assembly. This
technique
is
helpful
to
determine
failed
components
on
the
AS
assembly.
For problems
involving
a particular
controller,
it
is
recommended
that
an
HP
S9401A
Bus
Analyzer and
logic
analyzer be used
to
determine
the cause
of
the
problem.
As
an
initial test, verify
that
the
interface
responds
properly
to
the HP-IB test program
found
in
Section IV. Also verify that the
controller
interface
is
functioning
properly.
An
HP-IB test tape (HP part
Number
S9300-10002,
Revision
G)
is
available
for
use
with
the
HP8S
desk
top
controller.
8-326.
To
perform
signature analysis
for
the
AS
assembly, proceed
as
follows:
a.
Remove the
ac
power
cord
from
the
rear panel
of
the
counter.
b.
Remove
the
HP-IB assembly
from
the counter.
c.
Set
all
of
the
switches
on
the
DIP switch,
ASS1,
to
1 (open
or
upward).
d.
Connect
+S
volts and
ground
to
the
AS
assembly. The
+S
volts source can be
either
the
+S
volt
supply
in
the
counter
or
a separate
+S
volt
supply that
has
as
good
or
better
regulation than that
of
the
counter's
power
supply. If the
counter
is
used
as
the
+S
volt
source,
it
is
convenient
to
clip
on
to
TP2
on
the
motherboard
for
the
+S
volts and
TP10
for
the
ground.
On
the
AS
board,
+S
volts may be
connected
to
the
lead nearest W1.
Ground
may be
connected
to
HP
S384A
and
HP
S38SA
Service
the lead
of
C4
nearest
to
W1.
(Do
not
use ]3
pin
8
for
a
power
supply
connection.)
e.
Connect
a signature analyzer such
as
the
HP
SOOSB
to
the
AS
assembly
as
follows:
TIMING
POD
TEST
POINT
START
/ST/SP (green lead)
ST
(TP2)
STOP/QUAL (red lead)
SP
(TP3)
CLOCK (yellow lead) CK
(TP4)
(black lead)
(TPS)
f.
Make
the
following
settings
to
the
HP
SOOSB:
CLOCK negative slope
START
negative slope
STOP
negative slope
g.
Connect
a test lead between
PAT
(TP1)
of
the
AS
assembly and
ground.
If
the
counter
is
used
as
a
+S
vol~
supply
for
the
AS
assembly, reconnect
the
line
cord
to
the rear panel and switch
the
counter
on.
h. Remove the test lead
from
the
PAT
test
point.
The microprocessor checks this line at
Power-Up
and
then
goes
into
the signature analysis
mode.
The
PAT
point
must be
grounded
on
Power-Up
to
generate
START
and
STOP
signals,
however,
a valid signature
can
only
be taken at this
point
with
the
grounding
clip
removed.
All
other
signatures
on
the
AS
board should
remain identical regardless
of
the
status
of
PAT
(TP1).
i.
After
verifying the characteristic signatures,
Vee
and
ground,
verify
the
signatures shown
in
Figure 8-
50.
It
is
recommended
that
signatures
on
the
HP-IB
microprocessor,
US
be checked first
as
this
is
where
the
signal activity
is
generated.
8-327. The signature analysis
routine
does
not
verify
the
REN
line
and the
1/0
lines between
the
AS
microprocessor and the main microprocessor on the
motherboard.
Install
the
AS
assembly
into
the instru-
ment
and reset the
ASS1
Dl P switch
to
its orignal
setting. Enter the
following
program
into
an
HP8S
and
connect
the
HP-IB interface
to
the counter.
Note
that
for
line
10
in
the
program,
the
appropriate
address
for
the
counter
should be entered
(714
is
used
for
example only).
10 Remote 714
20 Local 7
30
Go to 10
40
End
8-328.
Run this program and verify activity at
ASUS(27).
If
there
is
no
activity at this
point,
trace back
through
U4D, U4A, and U2
to
locate
the
fault. Also,
verify activity on
US,
pins
3,
4,
S,
6,
16,
17, and
18.
If
there
is
no
activity
on
these lines, a
problem
may exist
in the interface
between
the
A 1 Microprocessor
assembly and
the
AS
HP-IB Interface Assembly.
8-43
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