Fluke 8050A - Page 58

MAINTENANCE
TROUBLESHOOTING
Table
4-13. Troubleshooting Gulde
TEST
AND
SYMPTOM
INITIAL
TURN
ON
Display
Blank
Display
"stuck"
with a
constant
reading
Reads
overload
for
several
minutes
after
turn
on
DISPLAY TEST
All
segments on
All
or no decimal points
Decimal
point
in wrong location
1 or
more
digits missing
1 or more
annunciator
missing
LINEAR VOLTAGE TEST
Display reading
is
out
of
tolerance
Constant
overrar.ge
in
DC
V
Does
not
respond
to
input
voltages
Does
not
range
properly
in
AC
V
dB VOLTAGE TEST
Does
not
go into dB
Does
not
autorange
Display
reading
is
out
of
tolerance
CURRENT
TEST
Does
not
respond
to
input
currents
Display
reading
is
out
of
tolerance
on
1
or
more
ranges
RESISTANCE/CONDUCTANCE
TEST
4-14
Reading
is
out
of
tolerance
on
200rl
and 2
krl
range
Reading
is
out
of
tolerance
on
other
ranges
Readings are
out
of
tolerance
on
high
ohms
Readings are noisy on
all
ranges
Residual
reading with
test
leads
ooen
POSSIBLE CAUSE
Power
supply
(06),
power switch,
interconnect,
microcomputer
U17
Touch
and
Hold
on,
011,
012
017,
Power On
Reset
(U17
pin 8)
No drive (
50
Hz
squarewave, TP12)
U 10,
interconnect,
U 17
U 16, U
17,
interconnect
U16,
range switch
input
to
U17
Ul0-16,
interconnect,
U17
Out
of
calibration
A/D, Check
TP6,
7,
and
8
for
proper
waveforms,
U18, U19,
U20
R2 open, A/D
input
U17,U31,
U22,07,08
Function
switch
input
to
U17
U17,U31,U22,07,08
AC V
is
out
of
calibration
Fuse
Fl,
F2
R16, R17, R18,
U6, U28,
CR1
R3
U1,
check
190V
de
calibration
RV1, RV2, RV3 overheated
from
severe overload
RT1,
C39
PCB
is
contaminated
see
cleaning
procedure
in
Section
4