Canon D78-5532, Service Manual, Page: 69 / 119

Part 4: Troubleshooting
4-7
1.4 No Picture
Check following steps.
No picture with all of
input sources
Check signal processing stage and LCD driving stage;
Check RGB S&H signals at test points TPVIDEOR,
TPVIDEOG, TPVIDEOB.
Check power supply circuit 15.5V and peripheral circuit.
Check ICs IC501, IC531, IC561, IC3501, IC3531, IC401,
IC301 and peripheral circuits.
Check PC source input stage;
Check IC5201<PC1/PC2 RGB-SW> and peripheral circuit on
the AV board.
PC1/PC2_SW signal (PC1: L) is output from pin 19 of
IC1804<Output Expander> and applied to pin 26 of IC5201
through IC5371<Buffer>.
The RGB output signals of IC5201 are sent to IC8201<A/D>.
No picture with PC1
[RGB] input source
No picture with PC1 [RGB
(SCART)] input source
Check PC source input stage;
RGB (SCART) signals are selected in IC5201 by
PC1/PC2_SW signal (PC1: L) and sent to IC101<Video
decoder>.
Check IC5201<PC1/PC2 RGB-SW>, IC101 and peripheral
circuit.
CV_SCART signal for sync is sent to pin 72 of IC101.
Check CV_SCART signal and test points TPVHS/TPVVS.
Check PC source input stage;
Check IC5201<PC1/PC2 RGB-SW> and peripheral circuit on
the AV board.
PC1/PC2_SW signal (PC2: H) is output from pin 19 of
IC1804<Output Expander> and applied to pin 26 of IC5201
through IC5371<Buffer>.
The RGB output signals of IC5201 are sent to IC8201<A/D>.
No picture with PC2
[RGB] input source
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Yes
Yes
Yes
No
No
No
No
Yes
Check PC/AV source selecting stage and processing stage;
Check IC5201<PC1/PC2 RGB-SW> and IC201<A/D
Conversion> and peripheral circuit.
PC1/PC2_SW signal (PC2: H) is output from pin 19 of
IC1804<Output Expander> and applied to pin 26 of IC5201
through IC5371<Buffer>.
Check IC4011<Sync-sw> IC4071 and peripheral circuit.
No picture with all of
computer input sources
Yes
No