Circuit Explanation - Haier 29FV6 Service Manual

Circuit Explanation

11. Circuit Explanation
A
. Electric circuits
1. Power
The FAIRCHILD power supply layout is applied and the switch transformer has four circuit
outputs: +B (130V), +15V, +32V and +7.5V
+B output:
Voltage produced by the transformer pin 10 shall after being rectified have four
circuits. Circuit 1 provides +B voltage through R810 to line output transformer.
Circuit 2 provides feedback voltage to controllable silicon through R815 and R815A.
Circuit 3 provides voltage to VM board. Circuit 4 provides tuning voltage to tuner
through R811.
+15V output
Voltage produced by the switch transformer pin 14 and rectified shall have the
following circuits. Circuit 1 provides audio amplification voltage to TDA6111Q.
Circuit 2 provides +12V current to optical coupler. Circuit 3 provides +15V voltage
to N804(KA7630). Circuit 4 provides +12V voltage through V804. Circuit 5 provides
input voltage to line driving transformer. Circuit 6 provides voltage to VM.
+32V output
Switch transformer pin 16 provides rectified voltage to accompany sound amplifier
N602（TDA7497）through VD807.
+8V output
+8V Voltage produced by N804 (KA7630) has 4 circuits. Circuit 1 provides power to
decoder board. Circuit 2 provides power to N701 (LV1116) through L701.
Three sources of +5V output
First source is (+5V) provided by pin 9 of N804 to CPU and decoder board. Second
source is (+5V) provided by N101 (KA78R05) to N102 (LA75503) and tuner AGC.
Third source is (+7.5V) from pin 18 of the switch transformer, and the voltage is
inverted to (+5V2) through V801 (2SC3852A) and then provided to the decoder
board.
Forward and flyback voltage +16V/+16V is provided to N301 (TDA8177) by pin 6 and
7 of FBT after being rectified; pin 3 provides 205V to audio frequency amplification
after being rectified.
2. Signal channels
TV signals are received, mixed, amplified and produced as 38M intermediate frequency
signals by the tuner. The 38M intermediate frequency signals shall be enter quasi
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