GC150AT/ATA
2.7.4 OVP : If +5V goes up too much, the induced voltage on pin 4 of T802 becomes large also. Suppose that it is
over 18 volts, ZD801 conducts, pin 3 of I801 is pulled up over 1 volt. The pulse train at pin 6 goes down to
zero, shutting Q803 off immediately.
2.7.5 SCP : If output terminal is short to ground, photo transistor does not conduct, hence Q806 does not conduct
either. Then oscillation of I801 is stop, shutting Q803 off immediately.
GC150AT/ATA Power Board Block Diagram
Rec.
Line FilterPowerOutput Rec. & Filter
&
Transformer
Filter
PWM Driver
FB
3. On-screen circuit (Circuit diagrams Main PWB)
I306 (gmZAN1) Embeded function.
On-screen menu screen is established and the resultant data are output from I306 (Circuit diagram MAIN PWB
, gmZAN1).
4. Video input circuit (Circuit diagram MAIN PWB)
The AC-coupled video signal is used to clamp the black level at 0V).
5. Definition converter LSI peripheral circuit (Circuit diagram MAIN PWB)
I306 gmZAN1 is the definition converter LSI.
The analog R, G, B signal input entered from the video input circuit is converted into the digital data of video
signal through the incorporated A/D converter. Based on this conversion, this device performs interpolation
during pixel extension. The source voltage for this device is 3.3V and the system clock frequency is 20MHz.
The withstand voltage level for the input signal voltage is 3.3V and 5V.
6. System reset, LED control circuit (Circuit diagram MAIN PWB)
6.1 System reset
System reset is performed by detecting the rising and falling of the 5V source voltage at I301.
6.2 LED control circuit
Green / amber is lit with the control signal of the LED GREEN and LED AMBER signal pin 32, 33 from I302
(Circuit diagram MAIN PWB).
2
7. EPROM for PnP (Circuit diagram MAIN PWB)
Page 2Circuit Description |
ACEC
