Fluke II Series Service Manual page 36

Maintenance
TROUBLESHOOTING
1.
Turn meter on
Does
meter
power up?
NO
YES
2.
Meter powers
up, but
does
not
come
out of
self-test.
YES
NO
1
3.
Meter comes up
with
missing segments.
YES
NO
X
4. Switch meter
to
V
and NO
-
apply
3V
dc.
Does
meter display 3
VDC?
YES
r-J
5.
Does meter autorange
NO
correctly?
YES
CHECK:
a
Power
supplies
TP1 -3.1Vdc+/-0.1V
TP3-
1.5V dc
U1 pin
48 -
-6V
dc (Battery voltage
-
TP
IV)
(If
any
of
these voltages are
high,low.
or missing,
replacement
of
U1
is
usually
necessary)
b.
For loose
pins
on U1/U2
c.
Battery Voltage
d.
SI
for
bad
contacts
e.
VR1
lor
1.2Vdc
f.
Shield for short to
Q3
g.
For solder
debris/shorts
CHECK:
a.
For Loose
pins
on U1.
U2
b.
For shorted C5,
6, 7,
or
8
c.
Contacts
of
SI
d.
For shorted pins
on U1/U2
e.
Y1 Frequency
@
32.768 kHz
CHECK:
a
LCD
for
cracks
b.
For contaminated display interconnects or display
contact areas
c.
For loose pins
on U2
d.
For cracks
in
U2
package
e.
Junction
of R11
&
12
for
1.6V
dc.
PROBABLE CAUSE:
a
R1 open
b.
RV1
or
RV2
shorted
c.
SI Contacts bad
d.
Z1
Open
or out of
tolerance
e.
U1
bad
f.
U1 locsa'sborted pins
PROBABLE
CAUSE:
a
U1 bad
b.
SI bad
PROBABLE
CAUSE:
Apply
3V@
500
Hz.
Does meter
display
3
VAC?
NO
a
U1 bad
(also
check
for
loose or shorted
pins)
b.
SI bad
c.
C9. C11 shorted —
-J
7.
Switch meter
to
£HK
Apply
100 ohms. Does
the meter
display 100&?|
NO
YES
x
8.
Switch meter
to A.
NO -
Apply
300
mA
dc.
Does
meter
display
300DC? YES
i
9.
Switch meter
to
Does
beeper sound
when
leads are shorted?
NO
PROBABLE
CAUSE:
a
R1 open
b.
El shorted
c.
Si bad
d.
Q1.
02
shorted
e.
Loose
pins
on U1
,
U2
f.
U1 bad
PROBABLE
CAUSE:
a
FI,
F2 open
b.
Si bad
c.
R7open
d.
Open
land patterns
in
current path
CHECK:
a
Connector
contact points
b.
For correct signal at contact points.
Should be
4.1
kHz
waveform.
(If
above checks
are
good. LSI
replacement
is
necessary.)
Figure
3-3.
Troubleshooting Tree
3-10