Fluke 8050A Instruction Manual page 64

TEST
AND SYMPTOM
POSSIBLE
CAUSE
MAINTENANCI
!N!T!ALTURN 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
overrange
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
Reading
is
out of
tolerance on 200^2 and
2 k$2
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
open
Power
supply
(Q6),
power
switch, interconnect,
microcomputer U17
Touch and
Holdon,Ql1,Q12
Q17, Power On
Reset
{U17
pin
8)
No
drive
(50
Hz
squarewave, TP12) U10,
interconnect,
U17
U16, U17,
interconnect
U16,
range switch input to U1
U10-16,
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, Q7,
Q8
Function switch input to
U17
U17, U31, U22, Q7,
Q8
AC
V
is
out of calibration
Fuse
FI,
F2
R16, R17,R18,
U6, U28,
CRT
R3
U1, check
190V
dc
calibration
RV1
,
RV2,
RV3
overheated
from
severe
overload
RT1,
C39
PCB
is
contaminated,
see
cleaning procedure
in Section 4