TM 11-5820-890-30-4
16-9. OPERATIONAL CHECK. Continued
Step 1. INPUT POWER CHECK.
Action
a.
b.
c.
Connect equipment as shown in figure 16-2.
Set 28 V: ON.
Read DMM.
Jumper test adapter TEST POINT 4
and TEST POINT 5.
Set LS-671/VRC ON/OFF switch
CB1 : ON.
Read DMM.
Step 2. VOLUME CONTROL CHECK.
Action
a. Set CAL: FCTN GEN.
FREQ: 1000 Hz (900 to 1100 Hz)
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.
c. Set RESP SEL: S1.
Set LOAD: 1.
Set TEST EQPT SELECTOR: SCOPE.
Read scope.
d. Set CAL: FCTN GEN.
FREQ: 400 Hz (360 to 440 Hz)
LEVEL: 3.4 V p-p (3.2 to 3.6 V p-p).
Set FCTN: SINE.
Set CAL: OFF.
Read scope.
Response
a. No response.
b. DMM reads -1 to 1 V dc. If not, the
ON/OFF switch (CB1) is bad.
c. DS1 lamp lights. If not, go to chart 1.
CB1 switch does not trip. If it does,
go to chart 2.
DMM reads 26 to 29 V dc. If not,
go to chart 3.
Response
a.
b.
c.
d.
A 1-kHz tone is heard
If not, go to chart 4.
Volume varies. If not,
over speaker.
t h e s p e a k e r
case/fIexible cable assembly is bad.
Scope CH1 displays a 1-kHz sine wave.
If not, go to chart 5.
Adjust speaker VOL control setting until
scope displays an 800 mV p-p, 1 kHz
sine wave.
NOTE
Do not change VOL control setting
again until after step 2 h.
A 400-Hz tone is heard over speaker.
If not, go to chart 6.
Scope CH1 displays a 400-Hz sine
wave at same amplitude as in step c.
If not, the rear cover assembly is bad.
16-5
