Wavetek 188 Instruction Manual page 30

Table
6-8.
Symmetry
Indication:
Waveform symmetry
problem
Check
1.
Set controls
to
initial
positions
(refer to
paragraph
6.4).
2.
II
symmetry
problem appears on
x
1.
x
10.
x
100 ranges
only,
problem
may
be R90 adjustment
<x
go to table 6-9
3
Perform
steps 5 through 12
of table
6-7.
then return to
this
table
4,
Verify
RUN
signal at
cathode
CR6
*
approximately
+3
5V
5,
Verify
U6
pin 4
and
U6
pm
15
vary
from
approximately
-
10
to
-
15V as
dial
is
rotated from
4
0
to
004.
6.
Verify
amplitude
of
SOR
signal at
cathode CfliO
is
approximately ± 2V
7.
Check
U5.CR6
Table 6-9. Capacitance
Multiplier
Indication:
Problem on bottom
frequency ranges
only.
Check
1 .
Set controls to initial
positions (refer to
paragraph
6.4).
2.
Check
for
0 Vdc
at
Ui
1
pms
2 and
6
3.
Check
for
approximately 0 Vdc
at
Ull pin 12
4.
Check
for
0 Vdc ± 5
mV
at
Ui
1
pin
10.
5.
Select
x 100 range, check Ui
1
pin
10
for
heavy
oscillations.
6.
Check that the signal at
U
1 1
pin
2 is
ampif
red
by
approximately 6
at
pin
1
(within
saturation
limits).
7.
Check
for
the
same
signal at
Ui
1
p«ns
6
and
7
as
at the emitter of
01
8.
Ensure
that
R93 and R94 are shorted
in
the
x
100 range
If
Faulty, Check
Check
for
normal operation
a
R49
adjustment.
b.
R45
adjustment.
Go
to table 6-10.
UI. U6. R52. R53.
a
07
circuit
b
U7
circuit.
c.
+ 5V supply
H-
—
Corrective Procedure
Chock
for
normal operation
on
x
IK range
SW2
-
SW4.
U11
circuitry
a
R90 adjustment,
b.
U11
circuitry.
C46. U11.
Ui
1
circuitry.
SW4.
U11
circuitry.
SW4.