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Chassis Service Adjustment Procedures
All service adjustments are factory preset and should not require adjustment unless controls and/or
associated components are replaced.
Note: Connect the (-) lead of the voltmeter to the appropriate ground. Use IC803’s heat sink when the HOT ground
symbol ( ) is used. Otherwise, use COLD ground (
) — Tuner shield, IC451’s heat sink or FA2.
MOMENTARILY CONNECT A JUMPER FOR ENTERING SERVICE MODE (FA1 to FA2 )
131.0V B+ Voltage Confirmation
1.
Set the Bright and the Picture to Minimum by
using the Picture Menu.
2.
Connect the DVM between C809(+ side) and cold
ground (
).
3.
Confirm that B+ voltage is 131.0V ± 2.5V. This
voltage supplies B+ to the Horizontal Output &
Flyback circuits.
Source Voltage Chart
120V AC line input. Set the Bright and the Picture to
Minimum by using the Picture Menu. Use cold ground
(
) for the (-) lead of the DVM.
C572 (+)
+5.0V ± 0.25V
TPD9
+13.0V ± 2V
C552(+)
+8.0V ± 1V
TPD8
+27.4V ± 2V
IC551 pin3
+9.0V ± 0.5V
CATHODE OF D554
+220.0V ± 15V
Adjust Picture Menu for normalized video adjustments.
B+ 5V Source Voltages
Volatile 5V:
C572, + side = IC552 pin 3, Tuner BP, IC101 (IF 5V).
MPU 5V:
Emitter Q002 = IC001 (V
DD
, AV
DD
).
Stand-by 5V:
IC001 (key in 1), I
2
C EEPROM (IC002), Remote
Receiver.
B+ 9V Source Voltage
IC551 pin 3 = IC101 (IF 9V), Tuner (BM).
B+ 12V (Stand- by)
Note: +16V when power is on
Cathode D001 = RL801 (on-off relay), Q002 (+5V
Reg).
High Voltage Check
1.
Select an active TV channel and confirm that
horizontal is in sync.
2.
Adjust Brightness and Picture using Picture Icon
menu so video just disappears.
3.
Confirm B+ 131V is within limit.
4.
Using a high voltage meter confirm that the High
Voltage is 28.30kV ±1.25kV.
T
U
N
E
R
IC 101
1
52
26
27
IC 001
1
64
32
33
IC 002
D554
C809
IC 803
IC 451
FOCUS
SCREEN
F801
HOT ( )
COLD ( )
FA1
DATA TP15
CLK
FA2
A11
SP
IC 551
RL801
TP
IC 6501
A31
A32
IC 2302
A61
IC 2321
IC 552
Q501
IC 4402
A7
A8
A-BOARD
Q551
C552
TPD8
TPD9
Figure 3. A-Board
Main Components
and Test Points
Summary of Contents for 27GX01B-501
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