TM 11-5805-356-34-1
Position
Control
(2) Connect the TS-2/TG signal output to either
ON-OFF . . . . . . . . . . . . . . . . . . . . . . . . .. OFF
SEND jack of the TH-22/TG.
Position corresponding to power
115V AC-230V AC-26V DC
(3) Operate the TS-2/TG controls to generate an
source being used.
undistorted Y character.
4W-2W-TEL . . . . . . . . . . . . . . . . . . . . . 4W
(4) Connect the AN/USM-281 signal input to
VF-20~ . . . . . . . . . . . . . . . . . . . . . . . . . 20 ~
(2) Interconnect the TH-22/TG 4WS TEL and
test point TP3 on send card 1A1.
2W-4WR terminals, connecting E3 to E5 and E4 to
(5) Connect the AN/USM-281 trigger input to
E6.
test point TP1 on send card 1A1.
(3) Connect the TH-22/TG to a power source.
(6) Operate the AN/USM-281 controls so that
(Use connector P1 for ac power, connector J5 for dc
sweep is triggered externally by a positive-going sig-
power.)
nal. Operate the sweep controls to provide a 1 milli-
(4) Operate the ON-OFF switch to ON.
second per centimeter sweep speed.
(5) Operate RING switch and note that the audi-
(7) Connect the TH-22/TG to a power source.
ble alarm sounds.
(Use connector P1 for ac power, connector J5 for dc
i. Break-in Circuit Sensitivity Test.
power.)
(1) Operate the TH-22/TG front panel controls
(8) Operate the ON-OFF switch to ON.
as follows:
(9) See that the waveform displayed on the oscil-
loscope is delayed 5 to 8 milliseconds.
NOTE
g. Receive Circuit Sensitivity Test.
A control for which no position is specified
(1) Operate the TH-22/TG front panel controls
may be left in any position.
as follows:
Position
Control
NOTE
ON-OFF . . . . . . . . . . . . . . . . . . . . . . . .. OFF
Position corresponding to power
115V AC-230V AC-26V DC
A control for which no position is specified
source being used.
may be left in any position.
4W-2W-TEL . . . . . . . . . . . . . . . . . . . . . 2W
Control
Position
NORM-REC-SEND . . . . . . . . . . . . . SEND
ON-OFF . . . . . . . . . . . . . . . . . . . . . . . . . .. OFF
(2) Connect the AN/USM-181 output to
115V AC-230V AC-26V DC
Position corresponding to power
1A1TP4.
source being used.
(3) Adjust the AN/USM-181 output to supply a
4W-2W-TEL . . . . . . . . . . . . . . . . . . . . . 4W
1180-Hz frequency at a 0-dbm level.
(2) Connect the AN/USM-181 output to the
(4) Operate the ON-OFF switch to ON. After
TH-22/TG 2W-4WR terminals.
approximately 2 seconds, note that the audible alarm
(3) On receive card 1A3, note the SENS strap-
sounds.
ping used. When the following steps use more than
(5) Insert open telephone plug into the SEND
one value, use the first value given if the strapping is
jack and remove.
H. Use the second value given in parentheses, if the
(6) Adjust the AN/USM-181 output to 0.
strapping is L.
(7) Measure continuous 1235.5 Hz 2 at
(4) Connect the TH-22/TG to a power source.
1A1TP4.
(Use connector P1 for ac power, connector J5 for dc
(8) Depress the RESET switch.
power.)
(9) Measure 1A2TP4 for no signal.
(5) Operate the ON-OFF switch to ON.
(6) Adjust the AN/USM-181 for a 1232.5 Hz
output frequency (ring frequency) at an output level
of 40 dbm (-- 18 dbm). After 1 second note that
a. General. Procedures are outlined in the trouble-
TH-22/TG alarm sounds.
shooting chart (b below) for localizing troubles to the
(7) Slowly reduce the AN/USM-181 output level
individual circuit or component. The procedures are
until the THRESHOLD indicator lights and the
initiated as a result of failing to obtain the indicated
alarm stops. Note the output level. It must be less
results when performing the operational tests (para
than 45 dbm (22 dbm).
3-6). When the procedure results in tracing the trou-
h. 20-Hz Signaling Tests.
ble to a pc board, replace the board. If the trouble is
(1) Operate the TH-22/TG front panel controls
traced to a stage on the chassis, use voltage and
as follows:
resistance measurements, as required, to isolate the
NOTE
trouble to a defective part. In the chart, the compon-
A control for which no position is specified
ent reference designation indicates its physi-
may be left in any position.
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