Wavetek 188 Instruction Manual page 32

Table 6-10. Trigger Logic (Continued)
Indication:
Generator
trigger
and
gate
mode
problems
Check
9.
Check
U9
pm
1
for a
TTl high.
10.
Check
U10
pm
10
for
a
TTL
high.
11.
Check
U10
pm
9 for
TTL
low
1 2.
Check anode
CR6
for
approximately
-
1
,5V
1
3.
Check
cathode
CR6
for
approximately
-
0.7V.
14
Check
omutor
Qi
i
for
0 Vdc
*
100
mV
1
5.
Connect an
external TTL
signal lo
TRIG
IN connector;
check
for
the inverse
of
that signal at
UlOpin
10.
16 Pross
TRIGfGATE
switch
and check
lor an approximate
20
ns negative
pulse
at
U10
pin 10 following the low-tomigh
transition of
the external
signal (increasing the frequency
of the
external generator makes
this
pulse
more
visible)
1 7.
Remove
the external signal
and
verify that
U
10
pm
5
goes from high
to
low
when
the
MAN
TRIG
switch
is
held
depressed
18
Release
the
TRIG/GATE
switch
(gated)
and check
that
U10
pin 10 goes
from
high
to
low
when
the
MAN
TRIG switch
is
pressed
19 Monitor 50Q OUT.
triangle function, for
0
Vdc
baseline
20
Press
MAN
TRIG
switch
and
check
50Q
OUT
for a continuous
triangle
while
the
switch
is
held.
Depress TRIG/GATE
switch
(triggered)
and
verify
a
single
cycle output
each
time the
MAN
TRIG
switch
is
depressed
Corrective
Procedure
a.
U9
b.
R73.
-
5V
supply.
a. U9.
b
U10.
a.
U10.
b
Q8
a.
CR15. 08.
R78.
b.
CR6.
a.
U5.
b.
U6
a
R81
adjustment.
b.
09-011
circuitry
a
E25. E26.
b
CR13, CR14.
c.
U9.
SW10
a
U9.
SW10.
b
C29
a
SW11
b. U10.
SW9.
R81.
R112
adjustments.
a.
UlOor
clock
signal
loUlO
from U7.
b.
C29
(pulse too narrow).