akira 21BHS3/CE, Service Manual

Page: 9 / 24

9
Model No: 21BHS3CE
Version 1.0
Pin 1 Standby control, “1” is on, “0” is off.
Pin 2 SCL
Pin 3 SDA
Pin 4 Tuning PWM output
Pin 5 Auto AV control SW, connected with the SCART 8
th
pin. Input. The rising edge or
the falling edge operates.
Pin 6 Key board input.
Pin 7 Volume
Pin 8 Mute control, “1” is mute, “0” is off.
Pin 9, Pin 12,
Pin 18, Pin 30,
Pin 35, Pin 41,
Pin 55 GND
Pin 10 BAND 1 control output.
Pin 11 BAND 2
Pin 13 SECAM PLL, connected with a capacitance (no use in this type).
Pin 14 +8V power source supply
Pin 15 Using a capacitor of 220n in series to GND. This pin decouples the internal digital
supply voltage of the video process and minimizes the disturbance to the sensitive
analogue parts.
Pin 16 Phase-2 control loop, this pin requires a capacitor at 2.2nF © in series to GND.
Pin 17 Phase-1 control loop filter connected to pin 17 is suitable for various signal
conditions like strong /weak and VCR signal. This is achieved by switching of the
loop filter time constant by changing the Phase-1 output current.
Pin 18 GND
Pin 19 Bandgap decoupling, the bandgap circuit provides a very stable and temperature
independent reference voltage. This reference voltage (4.0V) ensures optimal
performance of the analogue video processor part of the OM8370 and is used in
almost all functional circuit blocks.
Pin 20 East-west pillow signal output.
Pin 21, Pin 22 Vertical drive output.
Pin 23, Pin 24 IF input.
Pin 25 Reference current/ This pin requires a resistor to ground. The optimal reference
current is 100mA which is determined by this resistor. The 100mA reference
current should not be changed because the geometry processor is optimized for this
current. Furthermore the output current of vertical drive and EW are proportional to
this current.
Pin 26 Vertical sawtooth. This pin requires a capacitor to ground of 100nF.
Pin 27 AGC output. This output is used to control (reduce) the tuner gain for strong RF
signals.
Pin 28 Audio de-emphasis.
Pin 29 Sound decoupling. This pin requires a capacitor connected to ground. The pin acts
as a low pass filter needed for the DC feedback loop.
Pin 30 GND
Pin 31 Sound loop filter.
Pin 32 AVL filter
Pin 33 Horizontal drive signal output, needs a resistor in series to +8V.
Pin 34 Sandcastle output /flyback input.
Pin 35 External audio input, this pin should be grounded in this chassis.