30
8. Protection Block (HA-3 Chassis)
Standby light blinks six times – TV Shutdown
Refer to Figure 8-9 for this circuit and testing.
Circuit – IC001/pin 43 monitors the Q6.5Vdc from the Primary power supply (A Bd) to the Q box (QM and QI
boards). A short or excessive voltage on the Q6.5Vdc line will cause IC001 to shut off the AC relay (IC001/pin 69
goes LOW).
IC001
MAIN MICRO
M306V2MF
Q6004
Q6006
AMP
IC6001
T6002
PRIMARY
P.S
Q6005
OCP
2
1
43
50
69
STBY
5V
D6016
R6031
R6029
D6015
7.5V
D6021
R6043
R6032
10k
D6024
D6020
4.7V
LB
ERROR
Q6.5V
SOURCE
AC RELAY
RY6501
(DBd)
STBY LED
(BLINKS 6X)
CN7001
D 1.8V
D 3.3V
A BD.
B BD.
QM BD.
IC7002
DC-DC CONV.
C24
CN3020/
CN001
8/30/01
14TVP12 1332
FIGURE 8-9 - SHUTDOWN - 6X INDICATION
Testing – Unplug power to the Q box (CN7001) and power On the TV. If the TV does not shut down, the problem
is in the Q box. If the TV still shuts down, the problem is in the primary power supply. Measure “Q6.5Vdc” at
CN6005/pins 1 or 2 on the A board at power ON. A high of 8Vdc will trip the protection latch and shut down the TV.
The TV will not display A/V without the Q box (dark screen).
Standby light blinks seven times – TV Shutdown
There are two +135V OCP monitoring circuits. The first circuit will cause the Standby light to blink two times and
the second will cause the light to blink seven times. Both sensing and output circuits are on the D board, but the
indicating circuit is on the B board.
Circuit - Refer to Figure 8-10. The second OCP circuit consists of Q5004, Q5018, and IC5007 on the D board. It
monitors the +135V current through R5013 to the PWM Output (Q5003, Q5011) circuitry. This output circuitry
supplies B+ voltage (regulated 102Vdc) to the H. Output transistor Q5030. When there is excessive current
drawn by the Horizontal Output stage, OCP transistor Q5018 turns OFF, permitting IC3101/pin 34 to rise to a
threshold of 1.2Vdc (D board - CN5505/pin 8).
Y/C CRT Drive IC3101 immediately blanks the picture to prevent a CRT line burn and sends instructions (data) to
IC001/pin 31 to stop the AC relay voltage, which shuts down the TV.
Normally at power ON, Protect Mute Q3111 on the A board is turned on for five seconds to ground IC3101/pin 34
(CN3103/pin 8). This permits OCP comparator IC5007 (D board) time to stabilize, preventing premature blanking
and shutdown at power ON.
Summary of Contents for KD-34XBR2 - 34" Hdtv Fd Trinitron Wega
Page 77: ...74 RA 5A Chassis Board Layout ...
Page 108: ...APPENDIX ...
