Main Board Power On Checking - Sony KDL-43W7 C Series Service Manual

Troubleshooting
3-3-3. Main Board Power On Checking (for Main SP Lch & Rch) for BMX board only
No Checking Item
1 Check
IC7751 side-terminal of
L7751,L7752,
L7753,L7754
2 Check F7751 MainSP
(for BMX XM-H board
only)
3 Check F7751 MainSP
(for BMX XM-A, XM-AT
and XM-DT only)
4 Check IC7751 (Pin 5) at
R7879
(for BMX board only)
5 Check R7876, R7877,
R7878
6 Check R7736, R7738,
R7739, and R7740
Note : Parts location refer BMX Board : Reference A and Reference B.
OK
Switching Freq = 384kHz or 768KHz
±20KHz
Vrms = don't care
V(before fuse) = 12.5V ± 0.5V
V(after fuse) = 12.5V ± 0.5 V
V(before fuse) = 19.5V ± 0.5V
V(after fuse) = 19.5V ± 0.5V
V(before R7879) = 3.3V ± 0.5V
V(after R7879) = 3.3V ± 0.5V
Vdc = 3.3V ± 0.3V
R7738 = 12.288MHz
R7740 = 3.072MHz
R7739 = 48KHz
R7736 = moving CLK
All Vp-p ≈ 3.3V
If  NG
NG
No switching Go to next checking.
frequency at
either one of the
CL
No voltage. Check fuse broken?
Check CN9000 Pin 16
&18 got 12.5V?
No voltage. Check fuse broken?
Check CN9000 Pin 16
&18 got 19.5V?
No voltage.
Vdc < 0.8V R7877 NG,
Check IC7751
If no frequency at If sound source OK, but
R7738, R7739, at R7736 = NG, Muffin IC
and R7740, (IC1000) NG.
Muffin IC
(IC1000) NG.
If no frequency
at R7736 make
sure sound
source OK.
If  NG
Change fuse (5A).
Check power supply
board audio VCC.
Change fuse (5A).
Check power supply
board audio VCC.
Check +3.3V_MAIN
supply.
R7876, R7878 NG,
Check IC1000
34