Sony HCD-VX77 Service Manual page 16

VIDEO CD COLOR-BARS MODE
On this mode, the data of the color-bars signal as a picture signal and the 1kHz sine wave signal as a sound signal are output by the
mechanism control microcomputer (IC502) for video CD signal check. When measurement of the voltage and waveform on the VIDEO
board, perform it in this mode.
For reference, the color-bars signal can be observed at J302 (VIDEO OUT) and the sound signal can be observed at J101 (VIDEO/MD
(AUDIO) OUT) using an oscilloscope.
1. Connect the lead wire to both ends of the land of SL503 of the VIDEO board.
2. Turn the power on. Press CD button to select CD.
3. After 2 or 3 seconds later, connect the lead wire.
4. After measuring, remove the lead wire connected.
[VIDEO BOARD] (SIDE A)
SL501 SL502
TEST MODE
[VIDEO BOARD] (SIDE B)
SL503
TEST
SL502
MODE
SL501
16
SL503
CT503
VIDEO
FREQUENCY
IC502
IC505
IC507