— 14 —
SERVICE HINTS
Block Diagram (Power Fail Lines)
32
IC801 (CPU)
D663
Main
Main
R655
R656
5VTV
6.5V
14VTV
IC662
D661
21V
D664
R655
R656
9VTV
D665
31VTV
IC661
D654 D659
3.3VDM
14VDM
IC652
Front
K1901 (5)
K9FRB (5)
D618
D615
D621
21V
T601
K4D (2)
K6PDD (2)
P/D
TJ7
15
D652
D631
35V
21
D649
D623
D656
-15V
16
Q642
(Switching)
D486
D481
200V
T402
4
D429
D482
D428
9
Hold Down
(Circuit)
(FBT)
R487
R488
K5B (8)
K6PDB (8)
Q851/Q825
IC651
KG (21)
14
Power ON/OFF
Q1611
RL601
(Main Relay)
Video
IC2501
12
(CRT Driver)
K10G (21)
Q2320
POWER FAILURE DETECTOR
This unit is equipped with a Power Failure Detector function
included in the CPU which checks for an abnormal condi-
tion in the chassis power supplies, including the power
supply derived from the Horizontal Output Transformer.
If, while the power is on, a failure is caused by any of the
following that results in a low voltage supply, the CPU will
turn the unit off in 1.5 seconds to prevent further damage:
•
Failure within the power supply circuits.
•
A short circuit in the load side from the supply.
•
Stoppage of the Horizontal Output Oscillator caused by
the X-Radiation protection Hold-Down Circuit.
If, while the power is off, the power is switched on and any
of these failures remains uncorrected, the CPU will shut off
the power within three seconds.
Check the following if the unit is turned off by the power
failure detector.
1. Disconnect the AC power cord (120V AC line) for at least
10 seconds.
2. Connect a DC Voltmeter to the circuits shown below.
3. Press the Power key and check for the proper voltage
supplies.
4. If any of these voltages is low, the power failure detec-
tor should turn the unit off within three seconds.
5. Check all circuits shown below.
Note: This unit is equipped with a Power Surge Protection
feature included in the CPU. If power failure occurs
three times within 15 minutes, the CPU will automati-
cally stop functioning to help prevent secondary
damage. (TV will not turn on by pressing the power
key.) To reset the operating programs within the CPU,
disconnect the AC power cord for at least 10 seconds.