|
2 , the mute circuit
Thanks CL8830A models , which is why different models of mute circuit is different, but all the actual Kim will drive only two mute circuit , only introduced in this one , see another "single chip DVD principle of maintenance . " Muting circuit diagram mainly by Q1-Q3, D1-D3, C1, C2 and so on. Boot VCC capacitor C1 through D2 to charge the same time by charging the capacitor C2 24K resistor , capacitor charging for a long time due to C2 , Q3 base period is extremely low , Q3 are partial conduction , VCC through D2 → Q3 → Q1, Q2 base pole , Q1 Q2 turns on, the audio signal through Q1, Q2 of bypass . To achieve the purpose of the boot mute after fully charged C2 , Q3 ended , Q1 Q2 ended , the audio signal flow. Shutdown, VCC may be considered , at this time C2 discharges rapidly through D2 , Q3 is turned on is forward biased , C1 charges to the voltage during playback by D2 → Q3 → Q1, Q2 base , Q1 Q2 is turned on , the audio signals through Q1, Q2 of bypass , to mute off purposes .
Five examples of typical fault repair
( A ) the effect of RF signals , resulting in " showed no disc, correcting poor Dudie long time ."
1 ) associated with the reference voltage CXD2550 C143, C177, C178; ( in parallel with several electrolytic difficult problems )
2 ) associated with the reference voltage BA6392A C151, C152;
3 ) tracking error filter capacitor C145;
4 ) Focus error filter capacitor C144;
5 ) radial error filter capacitor C146;
6) RF filter capacitor C127;
7 ) imbalance correction circuitry external filter capacitor C135, C136;
8 ) external phase-locked loop filter capacitor C134.
( B) the "flying saucer , when transfer stop, not forward, reverse, " and other related failures with the spindle
|