Samsung DVD-A500 Service Manual page 64

6-7-2 Audio 5.1 CH. Analog
The Analog signals D/A converted in the CS4226(AIC3 : CODEC) passes through a Low Pass Filter (BIC15,
BIC35, BIC55 peripheral circuit), which are Level Amplified (BIC17, BIC37, BIC57 peripheral circuit), and then fed
to the AMP Board.
On the other hand, the Sub Woofer signal that passed the BIC72 is sent to Line Out if the SUB WOOFER is "ON"
in the Speaker Setup Mode.
However, if the configurations are set to the CONFIG2 Mode (Front Speaker is Large, Center Speaker, Surround
Speakers are Small), and the SUB WOOFER is "OFF" in the Speaker Setup Mode, the CONFIG2 signal at the
Micom is set to "LOW", mixing the Sub woofer Signal at the Front Left, and Front Right.
6-7-3 Audio 2 CH.
This is the circuit for stereo signals output.
If the Control Signals (SEL_IN_A, SEL_IN_B) sent to the 4052(AIC6 : Analog Switch) from the Micom are "00",
the audio signal of the DVD is selected, "10" selects the VCR Audio, and "01" selects the AUX Audio, which are
sent to the output of 4052(AIC6 : Analog Switch) pin 3, 13.
The signals explained above are also sent to the CODEC IC CS4226 to be A/D CONVERTED, and are also sent to
the Line Out of the Rear Panel.
6-7-4 AMP.
1) Power Amp
The STK402-480, STK402-680 are Hybrid IC that amplifies the Analog signals.
The Left and Right of the analog signals are fed to pin15 and pin19 of the STK402-480, Center, Left Surround and
Right Surround signals to the pin15, pin19, and pin21 of the STK402-680. Left and Right Signals with 30dB gain
comes out from pin 9, 10, 11, 12 of STK402-480, and the Center, Left Surround, Right Surround signals with equal
gain outputs could be found in pin 9, 10, 11, 12, 22, 23 of the STK402-680, which could be heard through the
speakers.
2) Relay Operation
This operation is to protect the speakers from the power on/off pop noise and for the protect mode.
The L and R of Front passes the L251, Center the L551, and the Surround passes the L851, which is connected to
the speaker. The Relay of each connection is connected to the Base of Q251, Q551, and Q851 respectively, con-
trolled by the on/off signal from the micom.
3) Protection Circuit
ΠShort protection
1st. Speaker short occur (in case of user short "Right Front" Speaker)
2nd. Emitter and Base of Q111 turn into Ground.
3rd. Q111 turns on and Collector of Q111 turn into Ground
4th. Q411 turns on (Base of Q411 turn "Lower than Ground" into Ground)
5th. Collector of Q411 (AMP_DET signal line) turn "High" into "Low"
6th. Micom detects that short occur
7th. Micom turn Relay Control signal line (Relay_F, Relay_C, Relay_S) "High" into "LOW"
8th. Collector of Q252, Q552, Q852 turn "Low" into "High"
9th. All relays open
´ DC protection
When DC is occurred from the output of the I200 or I800, the Q413 TR connected to each channels is operated to
activate the AMP_DET signal to the Micom when the collector voltage turn 5V into "Low", which enables the
Micom to operate the TR of Q251, Q551, and Q851, open the Relay.
Samsung Electronics
All manuals and user guides at all-guides.com
Circuit Descriptions
6-19