Sony KD-34XBR2 Training Manual page 41

A
1
A
11
A11 = CLOCK
DESC. PATH
CONN.
A
= MID BUSY
2
=
B BOX RST
2
=
M16 RXD
A
11
= M16 TXD
B
11
Loss of RXD/TXD Communications
Symptom 1 - Loss of RXD/TXD Communications between the Q box and the Main Micro results in a white
screen with no sound as if there is a break in the video path. This is because the Q box has no instructions
(communications) to configure the video ICs within the Q box so there is no active video output.
During this RXD/TXD Communications failure, the B and S data/clock communications is still active as long as
the TV is ON. This means main TV micro still communicates with the NVM ICs and TV operation ICs so the
TV deflection stages are working even though there is no audio and video.
Symptom 2 - If the power to the Q box is removed, the TV responds to the power ON/OFF button but the
screen is dark with no audio. The B and S data/clock communications is still active without the Q box power.
S data and clock bus
This data bus is bi-directional with the video processor on the A board (and AD board in the RA-5A projection
TV chassis), but unidirectional with the remainder of the ICs in the TV. The clock signal comes from Main
Micro IC001. Both data and clock signals are 4Vp-p and are always present as long as the TV is ON. This
output drops to 2Vp-p if the Q box power was removed (CN7001 unplugged).
B
1
B
11
CN8801
CN8601
A10 = DATA
B
A
1
1
10
CN005
11
B
A
1
1
(RST)
2
CN004
(R)
(T)
11 11
A BD.
TUNERS
FIGURE 10-3 - RA-5A CHASSIS COMMUNICATIONS
Q BOX
IC7205
DIG
PROCESS
IC8902
MID MICRO
CN007
S DATA, CLK
B CLK,
IC001
DATA
MAIN
MICRO
STBY
5V
CN002
A20 2
A25
B19
B25
CN1601
1 20
CN1602TO
CONV.BD.
38
10. Communications
S COMMUNICATIONS
CN005
CN007
CN002/
CN3022
B BD.
CN1602
IC004
B COMMUNICATIONS
NVM
CN002/
STBY
CN3022
5V
CN3022
1
CLOCK
IC13013
DATA
NVM
1 6 7
20
DATA CLK
A10 A11
1 13
A20
B19
2 1
DATA CLK
1
2
4Vp-p PRESENT
WHEN
TV IS ON
53TVP12 1365 9/6/01