HP 8340b User Manual

WARNING
|
When the
A19
power-on
safety
indicator
LED
is
on,
there
are
voltages pre¬
sent
inside
the
instrument
that
can
cause
personal
injury
or
death.
When
the
power
switch
is
set
to
STANDBY,
only the
A52, A53,
AND
A56
regulators
are
biased
«ff.
Never
short
a
capacitor
with
a
screwdriver
or
similar
direct
short.
Either
let
the
capacitor
bleed
off
via
normal instrument
loads
or
provide
a
discharge
path
by
applying
a
0.5W,
100^1
resistor
(via shielded
clip
leads)
across
the
capacitor
terminals.
y^w^ft^^if
{
CAUTION
j
To
protect
static sensitive
components,
troubleshoot
this
instrument
only
at
a
work
station
equipped
with
an anti-static
surface,
and
wear
a
ground¬
ing
strap.
When
handling
a
printed circuit
board,
hold
it by
the
edges;
never
touch
the
finger
contacts.
Use
low-static solder removal
tools
when
deso-
Idering
components.
Use only soldering irons
that
have
a
grounded
tip.
DO NOT
use
silicone based thermal
compound.
Silicone based
oil
migrates
past element
sockets,
switch
contacts,
or
printed
circuit
board
edge con¬
nectors,
raising contact
resistance,
or
electrically
isolating
the
contacts.
Silicone
based
thermal
compounds
disperse
into the
air,
depositing
them¬
selves anywhere
in
the
instrument.
Heat
increases
the
rate
of
dispersion.
Use
only rosin
mildly
activated
solder
when repairing
a
printed
circuit
board.
Rosin
activated
solder
can
cause
reliability
problems.
Cleaning solder
flux
from
a
printed
circuit
board after
replacing
a
compo¬
nent
causes
serious
reliability
problems.
When
you
replace
a
component,
solder
flux
remains on
the
newly soldered feedthrough
pads.
Solder
flux
contains caustic rosin
activating acids.
If
the
residual
rosin
is
left
on
the
board
undisturbed,
the
activators
remain encapsulated
(and
harmless),
but
cleaning
the rosin
off
(by
any
means)
releases
the
caustic rosin activators
and
spreads
them
over
the
printed
circuit
board.
The
caustic
chemicals
get under
trace edges
(all
printed circuit board
traces have undercuts along
the
edges
from
the etching
process)
and
can
not
be
washed
out.
In
time, these
chemicals
react
with
the
dissimilar
metals
in
the
trace
(nickel,
copper,
gold), slowly
dissolving
the
trace.
The
chem¬
icals
also
create
an
electrical path
between
traces,
causing
metal-ion
migration,
which
leads
to
high
impedance
shorts
and dendrite
growth.
NEVER
clean
PC
board
fingers
with
an
eraser.
NEVER
use tap
water
in
the
cleaning solution.
Chloride
contamination from tap
water,
from
salt
(skin
contact),
or
from
any
other
source,
can cause
reliability
problems.
Always
wear
a
ground
strap when
handling
any
internal
component
or
assembly.
HP
8340B/41B
Change
7
Assembly-Level
Service
Overall
Instrument
Troubleshooting
A-33

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English