Sangean DT-120 Service Manual page 14

( 3 ) Weak sensitivity on AM mode
Check whether the sensitivity is
recovered if antenna is directly
connected to the pin29 of IC1.
Yes
Check whether the IF waveform is
normal.
Yes
Check whether the tuning voltage is
normal.
Yes
Check whether the corresponding
RF tank circuit is normal.
( 4 ) PLL does not work
Check whether the D8 exceeds
12V DC.
Yes
Check whether the circuit of LPF is
normal.
Yes
Check whether the local oscillator
circuit is normal.
No Check the antenna wire and Q1
circuit. Then replace the abnormal
parts.
No
Check the IC1 circuit.
Then replace the abnormal parts.
No
Check the local oscillator circuit.
Then replace the abnormal parts.
No
Then replace the abnormal parts.
No
Check the DC-DC converter circuit.
Then replace the abnormal parts.
No
Check Q4.
Then replace the abnormal parts.
Yes Check whether IC3 and pin18 of IC1
is normal. Then replace the
abnormal parts.
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