Samsung MAX-805

6-1-3 Tuner Malfunction(FM/AM)
IZD1(8.2V) Voltage ok ?
Yes
Check TUNER IC(LA1836)
pin no.10 ; 8.2V
pin no.14 ; 7.2V
AM ; 0V ?
Yes
LC72131
CONTROL ok?
Yes
FM VT
LC72131 pin no.20
1.7V 7.5V ?
Yes
AM VT
LC72131 pin 20
Check the LC72131
CONTROL ok?
Yes
Yes
Check HIC1
pin 20 ?
LPF1,2
output ok?
Check BIC1 TDA7439 function ok?
Check FEP interior
pattern, and any line
disconnections.
 1) Power impaired
so repair defects.
2) LC72131 Oscillator
(HX1 : 7.2MHz) ok ?
3) System line ok?
No
Yes
Check for µ-com IC
Replace LC72131
No
HZD1 (5.6V) Voltage ok?
HIC1 (LC72131) FM/AM BAND
Switching ok?
No
No
No
No
No
No
No
0.9V 7V
?
Power section defective
RIC1(MC7812) Voltage ok?
OUT: 12V
Check the voltage ok ?
No
No
Samsung Electronics 6-3
Troubleshooting