Mitsubishi Electric LT-3280 Service Manual page 31

4 . 4 . 4 . 4 . 4 . Protection Circuit Protection Circuit Protection Circuit Protection Circuit Protection Circuit
LT-3280D and LT-3780D has two protection circuits and some fuses.
If the protection circuits work, The LCD turns to stand-by mode.
The protection operation can be confirmed by the blinking of the blue power LED.
And the content can be confirmed by the number of blinking within one cycle.
The following table shows the content of the operation.
Protection Circuit:
Name
Short1
Short2
Fuses:
Part No. Rated
F9A1
F9G2
F9G3
F9G4
F9G5
F9G6
F9G7
F9G8
F910
MODELS: LT-3280D/LT-3780D
Number Fault Location
of blinks
POWER-SUB1 or
1
Panel
POWER-SUB2 or
Panel
2 POWER or MAIN or
Panel (Only 18V or
P5V)
PCB
Value
6.3A
POWER
500mA
1A
500mA
1.6A
4A
1A
500mA
1A POWER-SUB1
Cause
Excessive current
on the 120V line.
The 24V line on
the POWER-SUB2
is low.
The voltage on any
of the following
output lines is low.
18V
P5V
AMPVCC （ 17V ）
4.5V
A3.3V
D3.3V
AD3.3V
D2.5V
A1.8V
Remark
AC line
S8V line ,S8V line for S5V
24V line for S8V and S5V.
24V line for S3.3V and D1.8V.
24V line for AMP VCC.
24V line for 18V.
24V line for P5V.
24V line for 4.5V.
IC920 is broken.
Page 31
Remark
Only LT-3780D
Only LT-3280D
Check the fuses
on POWER board.
(F9G2,F9G3,
F9G5~F9G8)