HP 8340b User Manual

17.
Press
[SHIFT]
[EXT].
If
REF is
flashing,
the
DUT
is
incorrectly
indicating
a
REP
unlock,
proceed
to
step
18.
If
REF is
not
flashing,
the
reference
loop
is
operating
properly.
18.
Switch the DUT
to
STANDBY
and
install
the
A29
assembly
on an
extender
board. Remove
the
A59
digital
interface
assembly
from
the
DUT
and
connect
the
frequency counter's
FREQ
STD
OUT
to
the
DUT's
INT FREQUENCY
STANDARD
input.
Switch the
DUT
ON
and
measure
the
voltage
at
A29P1
pin
7.
The
voltage
should be
approximately
—0.7V
(note:
if
the
voltage
is
0V,
the
feedthrough
capacitor
on
the
reference
loop
—
M/N
motherboard
may
be
shorted).
If
the
voltage
is
incorrect,
replace
A29.
If
the
voltage
is
correct
proceed
to
step
19.
19.
Switch
the
DUT
to
STANDBY
and
reinstall
the
A59
digital
interface
assembly.
Switch
the
DUT
on
and
measure
the
voltage
at
A29P1
pin
7.
If
the
voltage
is
no
longer
approximately
—0.7V,
remove
the
A59
digital
interface
and
check
the
motherboard
connector,
A62XA59,
for bent
pins.
If
none
of
the
pins
are
bent,
replace A59.
If
the
voltage
at
A31P1
pin 26
is still
approximately
—0.7V,
trou-
bleshoot
the
A59
assembly
for
a
false unlock
indication.
HP 8340B/41B
Reference Loop
Assembly-Level Troubleshooting
B-ll

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English