HP 8340b User Manual

ASS
Digital
Interface
Assembly-Level
Troubleshooting
DIAGNOSTICS
The
A60
processor
responds
to
inputs
from
the
A5Q
assembly
using
the
processor
service
request
and
change
detector circuitry for
the following
conditions:
•
oven
or
unlock
changes
•
overmod
or
unleveled
condition
changes
•
external
reference
switch
changes
•
sweep
events
from
the
A57
marker/bandcross assembly
CHANGE
DETECTORS
Verify the
Change
Detector
Circuitry
1.
Connect
a
logic
probe
or
storage oscilloscope to A59TP8.
2.
Change
the
rear
panel frequency standard
INT/EXT
switch and
verify
that
this
generates an
active
low
pulse.
Verify
that the
front panel
EXT
REF
LED
lights
when
the switch
is in
the
EXT
position.
3.
Press
[CW]
and
disconnect
one
of
the
snap-on
cables
in
the
phase
lock
loop
(e.g.
A39W1
at
A40J3).
Verify that the
front
panel
UNLOCK
indicator
on
the front panel
lights.
Verify
a
pulse
at
TP8.
4.
To check
HOVC,
disconnect
the
instrument from
line
power
for
five
minutes,
then
quickly
recon¬
nect
line
power
and
turn
the
power
switch
on.
Verify
that the
OVEN
light
goes
on
for
a
few
minutes,
and then
goes
off.
SERVICE
REQUEST
Verify the
Processor
Service
Request
1.
Press
[INSTR PRESET]
[CW]
and
verify
that the
RUN
light
on
the
A60
processor
assembly
is
off.
If
not,
the
LSRQ
line
is
pulled
down,
and
the
reset
circuitry
is
faulty.
HP
8340B/41B
A59
Digital
Interface Assembly-Level
Troubleshooting
F-ll

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English