Sony KV-32XBR400 Training Manual page 81

Then use your scope to examine the signal to the cathode. Go to CN9001/
pins 1, 3 and 5 to see if there is a signal coming into the C board. Next
check the signal at the CRT cathodes. If they are present, check the IK
signal from CN9001/pin 8 of the C board. You should see three pulses
and be able to change the level of the signal with the G2 control. If you
get about 1Vp-p pulses at pin 8, this is the normal output from the CRT/C
board so the problem is on the A board about IC201.
Shutdown - Standby light blinks six times
Circuit - IC701/pin 43 monitors the Set 5V supply from the power supply
on the A board. This voltage feeds almost all the boards. A short on the
Set 5V line will cause IC701 to shut off the AC relay (IC701/pin 69 goes
LOW).
Testing - At power ON, measure the "Set 5V" at regulator IC6007/Output
on the A board. The trip voltage is 3.7Vdc. If this voltage remains low at
power ON, unplug the B board within the A board and power ON again.
Shutdown - Standby light blinks seven times
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 A board.
Circuit - The second OCP circuit monitors the current through the PWM
Output (Q5001-3) that supplies B+ voltage to the H. Output transistor
Q5030. When there is excessive current drawn by the Horizontal Output
stage, Q5018 turns OFF, permitting IC201/pin 34 to rise to a threshold of
1.2Vdc. IC201 blanks the picture to prevent a CRT line burn and sends
data to IC701/pin 30 to shut down the TV.
Normal Operating Voltages
Location
IC5007/pin 8 0.07V
IC5007/pin 9 3V
IC5007/pin 1 2.6V
Q214/base 5V for 5 seconds
At power ON Operating
0V
3V
2.6V
0V
77
Q214 is turned on for five seconds at power ON to permit comparator
IC5007 time to stabilize.
Testing - If the Standby light blinks two or seven times, the problem is
most likely on the D board where the sensing and Horizontal Output stages
are. On the D board, if the Horizontal Output (Q5030), PWM (Q5003)
transistors, and video output ICs (C board) are good, suspect the compo-
nents in the sensing circuit (same board). The sensing parts are Q5004,
IC5007 and Q5018.
Verify that this circuit is causing the shutdown by disconnecting the H.
Output Transistor Q5030 and monitor the voltage at CN5505/pin 8 as you
power ON. If this voltage rises above 1 volt, this +135V OCP circuit is
responsible. Suspect Q214 on the A board and the following main parts
on the D board:
R5013, Q5004, IC5007, delay cap C5006, Q5018.
Bridge Connectors
CN6505
6 1
CN6501
CN6504
CN6506
CN5503
D
Board
CN5505
CN5501
10
1
CN6006
1
8
6
CN702
CN6005
1
11
IC
CN703 60
07
1
10
A
CN201
Board
1
10
IC6007
CN203
O
1
8
CN706
1
I O G n/c
Back of TV
Hot
Ground