TM 11-6525-586-45
CAUTION
Depending upon the nature of the operational
symptoms, one or more of the localizing proce-
Before connecting the signal generator
dures will be necessary. When trouble has been
to a power source, read the CAUTION
localized to a particular stage, use voltage and
preceding paragraph 21.
resistance measurements to isolate the trouble to
The test equipment connections vary from test
a particular part (para 27).
to test. Remove the signal generator from its case
b. Use of Troubleshooting Chart. When an ab-
normal symptom has been observed in the equip-
below.
ment, look for a description of this symptom in
a. Power Supply Connections. There are no
the "Symptom" column and perform the correc-
external power supply connections required ex-
tive measure shown in the "Corrective Meas-
cept for prime excitation power. All power sup-
ures" column. If no operational symptoms are
plies are in integral part of the signal generator.
known, begin with the Preventive Maintenance
b. Test Equipment. Connect the test equipment
and Services Charts (TM 11662558612 ) and
as specified for the particular tests. All test con-
proceed until a trouble symptom appears.
nections vary from test to test.
c. Conditions to Tests. All checks in the chart
are to be conducted with signal generator con-
nected to a power source as described in para-
2-5. Localizing Troubles
graph 2-4.
a. General. In the troubleshooting chart below
d. Troubleshooting Chart.
procedures are outlined for sectionalizing trou-
bles to the power supplies, modulator, RF oscil-
NOTE
lator, or meters, and for localizing troubles to a
Perform the operations in the equipment per-
stage within the various sections. Parts locations
formance check list (TM 11-6625-586-12) before
are indicated in figures 21 through 221. Volt-
using this chart, unless trouble has already been
localized.
age measurements are given in paragraph 212.
Correction
Probable Trouble
Symptom
Check that input ac voltage is
No ac power is being supplied.
1. OPERATE and STANDBY
available.
indicators do not light when
Replace fuse. If replaced fuse blows,
Open fuse F1 or F2.
OPERATE-OFF-STANDBY
check for shorts. Refer to figures
switch is turned to OPERATE
2-2 and 6-8(1).
and STANDBY, respectively.
Repair or replace defective part.
Switch S3, switch S4, capacitor C36 or
Refer to figures 2-2 and 6-8(1).
capacitor C37 defective.
Repair or replace defective part.
STANDBY indicator DS2 or lamp
2. STANDBY indicator does not
Refer to figure 6-8 (1).
socket defective.
light when OPERATE-OFF-
Repair or replace defective part.
Resistor R63 or R65 defective.
STANDBY switch is turned
Refer to figures 2-2 and 68(1).
to STANDBY.
Repair or replace defective part. Refer
Transformer T1 defective.
3. OPERATE indicator and two dial
to figures 2-1 and 6-8 (1).
illuminating indicators do not
light when OPERATE-OFF-
STANDBY switch is turned to
OPERATE.
Repair or replace defective part.
OPERATE indicator DS5 or lamp
4. OPERATE indicator does not
Refer to figure 68 (1).
socket defective.
light when OPERATE-OFF-
Check and replace if necessary.
Resistor R68 defective.
STANDBY switch is turned
Refer to figure 2-8 and 6-8(1).
to OPERATE.
Check for +44 volts dc at TP1 (fig
25-volt power supply defective.
5. OPERATE indicator lights but
all signal generator functions
bridge rectifier CR5 through CR8
are inoperative.
check for +25 volts dc, at TP2. If
no voltage is present, check transistors
Q9 and A5Q10 through A5Q13. Repair
or replace defective part. Refer to
figure 6-8 (1).
Check for +18 volts dc at TP3 (fig
12-volt power supply defective.
23). If no voltage is present, check
bridge rectifier CR9 through CR12
2-3
