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TM 11-5820-890-30-5
17-9. OPERATIONAL CHECK. Continued
Step 1. INPUT POWER CHECK.
Action
Response
a. Connect equipment as shown in figure 17-2.
a. No response.
b. Set 28 V: ON.
b. DMM reads -1 to 1 V dc. If not, the
Read DMM.
ON/OFF switch (CB1) is bad.
c. Jumper test adapter TEST POINT 4
c. DS1 lamp lights. If not, go to chart 1.
and TEST POINT 5.
CB1 switch does not trip. If it does,
Set LS-671/VRC ON/OFF switch
go to chart 2.
CB1: ON.
DMM reads 26 to 29 V dc. If not,
Read DMM.
go to chart 3.
Step 2. VOLUME CONTROL CHECK.
Action
Response
a. Set CAL: FCTN GEN.
a. A 1-kHz tone is heard over speaker.
FREQ: 1000 Hz (900 to 1100 Hz)
If not, go to chart 4.
LEVEL: 3.4 V p-p (3.2 to 3.6 V p-p).
Set FCTN: SINE.
Set CAL: OFF.
Set STIM SEL: FCTN GEN.
b. Adjust speaker VOL control setting.
b. Volume varies. If not, the speaker
case/flexible cable assembly is bad.
c. Set RESP SEL: S1.
c. Scope CH1 displays a 1-kHz sine wave.
Set LOAD: 1.
If not, go to chart 5.
Set TEST EQPT SELECTOR: SCOPE.
Adjust speaker VOL control setting until
Read scope.
scope displays an 800 mV p-p, 1 kHz
sine wave.
NOTE
Do not change VOL control setting
again until after step 2 l.
d. Set CAL: FCTN GEN.
d. A 400-Hz tone is heard over speaker.
FREQ: 400 Hz (360 to 440 Hz)
If not, go to chart 6.
LEVEL: 3.4 V p-p (3.2 to 3.6 V p-p).
Scope CH1 displays a 400-Hz sine
Set FCTN: SINE.
wave at same amplitude as in step c.
Set CAL: OFF.
If not, the rear cover assembly is bad.
Read scope.
17-5
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