Section V
Paragraphs 5-10 to 5-11
OTALHARMONIC
AUDIO
5-11. It is possible to detect many troubles in Signal
DISTORTION*
TOLERANCE
FREQUENCY
Generator SG-13/ARN without removing the instru-
(PERCENT)
(PERCENT)
(CPS)
ment from its case. The METER switch in conjunc-
tion with the meter on the front panel can be used to
6
2
30
check for the presence of input voltage to the signal
8
2
90
generator (LINE), +230-volt supply voltage (B+), and
8
2
150
r-f carrier level (CAR). Audio signals can be ob-
15
20
1000
served with an oscilloscope or an a-c vacuum tube
10
9960
voltmeter connected to test point
AUDIO OUT
Accuracy of r-f signal 0.0065%
jack J1408. Table VIII lists probably trouble symp-
Accuracy of r-f level 30%
Measured at
q
pin 2, V1508.
toms with causes and remedies.
0.75
VOR accuracy
POSSIBLE CAUSE OF
TEST
CONTROL
NORMAL
ABNORMAL INDICATION
POINT
STEP
POSITIONS
INDICATIONS
Fuse F1401 or F1402. No
Pilot lamp lights and meter
1
Turn SET LINE TO 21V
power from power source.
reads d-c voltage input.
control from OFF. Set
Connecting power cables.
METER switch to LINE.
Dynamotor D1401.
2
Meter indicates Bt voltage.
Set METER switch to B+
R-f chassis. Tubes V1501
Set NAV-GS switch to
Meter points to red line.
3
through V1506. Coaxial
NAV OUTPUT
NAV. Set METER
R-f output present at test
jack J1406
relay K1401. Cable W1401.
switch to CAR. Red
point.
line the meter with
CARRIER SET control.
Univerter chassis. Tubes
4
R-f output present at test
Set NAV-GS switch to
GS OUTPUT
V1510 through V1513.
point.
GS.
jack J1501
Cables W1501 and W1502.
Tubes V1408, V1507 through
Set AUDIO SELECTOR
Proper audio signal pres-
5
V1509.
to each of its nine
ent at test point.
AUDIO OUT
jack J1408
positions.
No 9960-cps signal. Tubes
Same as
6
9960-cps signal frequency
Set AUDIO SELECTOR
step 5.
V1406 through V1409. No
to VOR,
modulated by 30 cps pres-
LOC and
30-cps modulation: Tubes
9960 FM.
ent at test point.
V1401 through V1403.
I
Same a s
Tubes V1401 through V1403.
Set AUDIO SELECTOR
30-cps signal present at
7
step 5 .
to 30~VAR
test point.
No 90-cps signal Tube
8
Same as
Set AUDIO SELECTOR
90-cps and 150-cps signals
step 5.
to TONE LOC, GLIDE
present at test point in TONE
V1405. No 150-cps signal
LOC and GLIDE SLOPE.
SLOPE, 90~ and
Tube V1404.
150~.
90-cps signal in 90~ and
150-cps signal in 150%.
9
Perform a VOR accu-
VOR error should not ex-
30-cps oscillator off fre-
racy check (paragraph
ceed 0.75.
quency. See Section VI,
Audio chassis out of align-
10
Accuracy should meet re-
Perform tone localizer
and glide slope accuracy
quirements given in
ment. See Section VI,
checks (paragraphs 5-5
through 5-8).
