Canon D78-5311, Service Manual

Page: 69 / 122

1.2 No Picture
The possible causes of No Picture are listed below. Please check following and refer to
video signal processing diagrams in the figure opposite.
1) No picture from Video source
●
Composite video input
• Check composite video signal at pins 45 and 46 of K3U on the Main Board and
K10U on the AV Board.
• Check Y, C signals at pins 7 and 9 of IC2101.
• Check Y, C signals at pins 5 and 7 of IC1101
●
S-video input
• Check S-video signals at pins 39, 40 (Y), 41, 42 (C) of K10U and K3U.
• Check Y, C signals at test points TP11SC and TP11SY.
• Check Y, C signals at pins 43 and 44 of IC1101.
●
Component input
• Check component signals at pins 49, 50 (Pb), 51, 52 (Pr) of K10U and K3U.
• Check component signals (Y, Pr, Pb) at test points TP11CV, TP11PR and TP11PB.
●
All of video signals
• Check component signals (Y, Cb, Cr) at pins 21, 22 and 23 of IC1101.
• Check component signals (Y, Cb, Cr) at pins 69, 68 and 67 of IC4101.
• Check component signals (Y, Pb, Pr) at pins 75, 74 and 73 of IC4101.
• Check Sync signals (AV_HSYNC, AV_VSYNC) at pins 4 and 9 of IC1101.
• Check Sync signals (AV_HSYNC, AV_VSYNC) at pins 65 and 66 of IC4101.
• Check RGB signals at pin 39, 37 and 35 of IC4101.
• Check RGB signals at pins 15, 4 and 14 of IC3101.
• Check blanking signal at pin 9, 10, 11 of IC3101.
• Check RGB signals at pins 1, 3 and 5 of IC5241.
• Check Sync signals (AV_HSYNC, AV_VSYNC) at pins 2 and 12 of IC6261.
• Check AV/PC switching signal at pin 22 of IC5241 and pins 10 and 11 of IC6261.
AV: Low, PC: High
Part 4: Troubleshooting
4-4