38
10. Communications
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).
IC13013
NVM
IC004
NVM
IC001
MAIN
MICRO
IC8902
MID MICRO
IC7205
DIG
PROCESS
CN002
10
11
11
B
1
A
1
2
11
B
1
A
1
13
1
(RST)
(T)
STBY
5V
STBY
5V
CN007
S DATA, CLK
(R)
A10 = DATA
A11 = CLOCK
CN8801
CN8601
Q BOX
B CLK,
DATA
B BD.
CN005
CN004
BOX RST
M16 RXD
M16 TXD
B
2
A
11
B
11
=
=
=
CONN.
DESC.
PATH
A
2
=
MID
BUSY
A20
2
B19
1
6 7
1
20
A
1
B
1
A
11
B
11
TUNERS
CN1601
CN1602TO
CONV.BD.
A BD.
CN3022
FIGURE 10-3 - RA-5A CHASSIS COMMUNICATIONS
53TVP12 1365
9/6/01
1
20
CLOCK
DATA
4Vp-p PRESENT
WHEN
TV IS ON
A25
B25
S COMMUNICATIONS
DATA CLK
CN005 A10 A11
CN007 1 13
CN002/
CN3022
CN1602 2 1
B19
A20
B COMMUNICATIONS
DATA CLK
CN002/
CN3022
2
1
Summary of Contents for KD-34XBR2 - 34" Hdtv Fd Trinitron Wega
Page 77: ...74 RA 5A Chassis Board Layout ...
Page 108: ...APPENDIX ...
