Sangean DPR-25+, Руководство по обслуживанию

Страница: 21 / 46

( 3 ) Weak sensitivity in FM
Check whether the sensitivity is Yes Check the antenna wire and BPF
recovered if antenna is directly circuit.
connected to the pin 2 of IC12. Then replace the abnormal parts.
Yes
No
Check whether the IF waveform is
normal.
Check the IC12 circuit.
Then replace the abnormal parts.
Yes
No
Check whether the tuning voltage
is normal.
Check the L4 local oscillator circuit.
Then replace the abnormal parts.
Yes
Check whether L8 and TC2 the No
corresponding RF tank circuit are Then replace the abnormal parts.
normal.
( 4 ) PLL does not work
No
Check whether the C53 exceeds
15V DC.
Check the DC-DC converter circuit.
Then replace the abnormal parts.
Yes
No
Check whether the circuit of LPF
is normal.
Check Q2 and Q3.
Then replace the abnormal parts.
Yes
Yes
Check whether the local oscillator
circuit is normal.
Check C121 and D11.
Then replace the abnormal parts.
21