Samsung MM-28 Service Manual page 24

6-1-3 Tuner Malfunction (FM/AM)
IZD1 Voltage ok?
Yes
Check TUNER IC(LA1836)
pin no.10 ; 7.6V
pin no. 14 ; 6.5V
AM ; 0V?
Yes
FM VT
LC72131 pin no.20
1.7V 7.5V?
Yes
AM VT
LC72131 pin no.20
0.9V
Yes
Check HIC1
pin 20?
Yes
LPF(IL1,IL2)
output ok?
Samsung Electronics
No
Check IZD1 (8.2V),IR1
No
HIC1 (LC72131) FM/AM BAND
No
No
7V?
No
Yes
Check TDA7430 function ok?
HZD1 (5.6V) Voltage ok?
Switching ok?
Check the LC72131
Control ok?
Check the LC72131
Control ok?
1) Power settion defective?
No
2)LC72131 Oscillator(HZ1 :
7.2MHz) ok?
3)System line ok?
Yes
Check for µ-com IC
No
Replace LC72131
No
Check FEP interior
Yes
pattern, and any line
disconnections
Troubleshooting
No
6-3