Video Troubleshooting - Mitsubishi Electric LT-2220 Service Manual

MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050
2. No picture displayed and picture errors (It applies both LT-30XX and LT-22XX)
Note ) It applies when there is no screen display or an unusual screen is outputted, although
power supply is turned on and the back light is turned on.
Before checking, perform the initial setup. (Input before the initial setup is channel 3 of TV.)
* Input source changes in following order with DEVICE UP button of remote control or
DEVICE
button of front switch.
TV
2-1. No picture displayed and picture errors of PC signal.
Enter an input of WXGA(60Hz) gray scale
in D-sub connector(J2A1), and select PC INPUT.
(Push the device UP button 5 times.)
And then, perform AV reset by front switch.
The video level inputs above 0.7Vp-p.
Is all harness connected correctly?
(especially between PWB-MAIN
and LCD PANEL (J4A0-LCD))
YES
NO
Is OSD available?
YES
2-1-1 (P*)
Component1 Component2
DVI
NO
Poor harness connection or
defective cable.
Problem is in IC300 or IC4A0 or IC4A1
(and peripheral circuits). Are the
specified voltages available at the
connectors below?
CN
Name
S5V J303
S3.3V J303
D3.3V J190
Psave1* J712
* control signal of D3.3V
YES
2-1-2 (P*)
Input1
PC
NO
Pin No. Voltage
12 5Vdc
13 3.3Vdc
7 3.3Vdc
5 3.3Vdc
Input2
0.7Vp-p
Problem is in the following
circuit (and peripheral
circuits) .
Voltage with PWB
problem including
the circuit
in problem
S5V SET(SUB)
S3.3V SET(SUB)
D3.3V SET(SUB)
Psave1 MAIN