Troubleshooting guide (h/s)

1.

GT-9720A H/S
TROUBLESHOOTING
GUIDE(H/S)
1. WHEN TRANSMISSION(TX) IS NOT
OPERATED
2. WHEN RECEIVING(RX) IS NOT
OPERATED
3. WHEN LCD IS NOT
OPERATED
CHECK POWER
CHECK POWER
ON
NO
CHANGE X1
IS X1
OSCILLATING?
OFF
CHECK BATTERY AND
SWITCH
ON
CHANGE X1
NO
IS X1 OSCILLATING?
OFF
ON
CHECK POWER
OFF
CHANGE X1
CHECK BATTERY
AND SWITCH
NO
CHANGE BATTERY OR
CHARGE BATTERY
IS X1 OSCILLATING?
YES
YES
CHECK C19
NO
IS PIN15
OF U6
OSCILLATING?
YES
CHECK C19
NO
YES
INPUT SIGNAL TO MIC
(1KHz,10mV)
NO
CHANGE U6
IS SIGNAL
OUTPUT AT
PIN6 OF U6?
IS PIN15 OF U6
OSCILLATING?
YES
INPUT SIGNAL FROM SIGNAL GENERATOR TO
ANTENNA
(904.5125MHz,FM:2KHz,AUDIO:1KHz,LEVEL:60dB
uV)
CHANGE RF MODULE NO
OF H/S AND CN1
IS SIGNAL OUTPUT
AT PIN16 OF CN1?
IS V1 EXISTS?
NO
CHECK BATTERY
AND SWITCH(SW1)
YES
IS V2 EXISTS?
NO
YES
IS V3 EXISTS?
NO
YES
YES
YES
NO
CHECK CN1
IS SIGNAL
OUTPUT AT
PIN8 OF CN1?
CHECK U6
NO
IS SIGNAL OUTPUT
AT PIN21 OF U6?
YES
YES
SET IS CORRECT
CHECK U7 AND CN3
NO
IS SIGNAL OUTPUT
AT RECEIVER?
YES
SET IS CORRECT
IS LCD CORRECT?
YES
SET IS CORRECT
NO
CHANGE LCD

2.

TROUBLESHOOTING
GUIDE(B/S)
1. WHEN DIALING IS NOT
OPERATED
2. WHEN RING IS NOT
OPERATED
CHECK POWER
CHECK POWER
OFF
ON
CHANGE X4
NO
IS X4
OSCILLATING?
WHEN YOU ARE NO
DIALING,IS X1
CHANGE X1
OSCILLATING?
YES
CHANGE X3
NO
NO
CHANGE X4
NO
YES
IS X3
OSCILLATING?
IS TONE
NO
OUTPUT AT PIN12
CHANGE U5
OF U5?
YES
CHANGE U13
ON
CHANGE X3
NO
YES
IS TONE
OUTPUT AT PIN3
OF U13?
CHANGE U12
IS RING
NPUT AT PIN1
OF U4?
YES
YES
IS X3
OSCILLATING?
NO
IS RING
OUTPUT AT PIN3
OF U12?
NO
IS RING
OUTPUT AT PIN5
OF U3?
YES
IS TONE
NO
OUTPUT AT EMITTER
CHANGE Q10
OF Q10?
YES
IS TONE
OUTPUT AT TIP
AND RING?
IS X4
OSCILLATING?
CHANGE U3
YES
NO CHECK BD1 AND
CHECK POWER
ON
CHANGE X4
NO
NO
CHANGE X2
NO
CHANGE U13
CHANGE U6
NO
NO
IS SIGNAL
OUTPUT AT PIN3
OF U13?
YES
NO
CHECK U22
CHANGE Q10
IS SIGNAL
OUTPUT AT EMITTER
OF Q10?
YES
CHECK BD1 AND NO
AR1 AND L3,L4
IS SIGNAL
OUTPUT AT TIP
AND RING?
NO
CHECK T1 AND
CN1 AND SPK1
5. WHEN RECEIVING(RX) IS NOT
OPERATED
CHECK POWER
OFF
CHANGE U19
CHANGE U22
NO
IS SIGNAL
OUTPUT AT PIN1
OF U22?
CHECK U1 AND U2
INPUT SIGNAL FROM SIGNAL
GENERATOR
(814.5125MHz,60dBuV
FM:2KHz,AUDIO:1KHz)
CHECK RF MODULENO
OF B/S
NO
IS SIGNAL
OUTPUT AT PIN6
OF U11?
CHANGE U11
NO
IS SIGNAL
OUTPUT AT PIN14
OF CN4?
YES
SET IS CORRECT
NO
IS SIGNAL
OUTPUT AT PIN20
OF U11?
NO
IS SIGNAL
OUTPUT AT PIN7
OF U22?
NO
IS RX
RECEIVED SIGNAL?
YES
CHANGE U22
YES
YES
CHECK CN4
IS SIGNAL
OUTPUT AT PIN4
OF CN4?
YES
YES
CHANGE U11
OFF
ON
INPUT SIGNAL TO MIC
(1KHz,312mV)
NO
YES
NO
IS X2
OSCILLATING?
YES
YES
IS SIGNAL
OUTPUT AT PIN1
OF U6?
IS X4
OSCILLATING?
YES
YES
IS USER OGM
RECORDED?
IS SPK RINGING?
4. WHEN TRANSMISSION(TX) IS NOT
OPERATED
INPUT SIGNAL TO MIC
IS SIGNAL
INPUT AT PIN15
OF U12?
YES
SET IS CORRECT
CHECK U1 AND U2
YES
CHANGE U4
YES
OFF
IS USER OGM
RECORDED?
IS RING
NO
OUTPUT AT PIN6
OF U4?
AR1 AND L3,L4
YES
ON
AR1 AND C13,R7
YES
SET IS CORRECT
3. WHEN USER OGM IS NOT
OPERATED
CHECK POWER
NO CHECK L3,L4 AND
YES
IS TONE
NO
OUTPUT AT PIN1
CHANGE U6
OF U6?
YES
OFF
CHANGE RECEIVER
YES
SET IS CORRECT
CHECK U1 AND U2