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POWER FAILURE DETECTOR
This unit is equipped with a Power Failure Detector function included in the CPU which checks for an abnormal condition 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.
Block Diagram (Power Fail Lines)
IC801 (CPU)
14
Q851/Q825
39
Power ON/OFF
K9FRB (5)
K1901 (5)
Front
Q1611
RL601
(Main Relay)
Video
D2302
9V
D2303
5V
(CRT Driver)
IC2501
12
3. Press the Power key and check for the proper voltage supplies.
4. If any of these voltages is low, the power failure detector should turn the unit off within three seconds.
5. Check all circuits shown above.
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 automatically 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.
SERVICE HINTS
D663
5VTV
IC662
D662
5VIP
IC663
D661
IC661
9VTV
D664
R655
R655
21V
R656
R656
D665
31VTV
D654 D659
3.3VDM
D676 D653
2.5VDM
K8VBD (19)
K23VBD (19)
IC2303
14V
14V
IC2304
6.5V
Hold Down
(Circuit)
k23VDA (15)
K8VDA (15)
D1281
Main
6.5V
D7103
IC651
14VTV
KG (6)
K10G (6)
K6PDD (2)
K4D (2)
D622
D649
IC652
14VDM
D652
IC653
DAF
D4365
IC4304
12V
D4366
IC4305
5V
K4DF (9)
K43B (9)
Main
K5B (8)
K6PDB (8)
— 18 —
IC1281
9V
14V
R7112
5V
Q7101
D7102
IC7103
2.5V
D7101
P/D
D509
D508
D510
Vertical
Output
D621
21V
TJ7
D623
D656
Q642
-15V
D631
35V
D486
D481
R487
200V
R488
D429
D428
D482
Hold Down
(Circuit)
AV
IC7102
3.3V
(V Out)
3
IC501
(Switching)
15
T601
16
21
(FBT)
4
T402
9
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