Audio Troubleshooting - Mitsubishi Electric LT-2220 Service Manual

MODELS: LT-2220 / LT-2240 / LT-3020 / LT-3040 / LT-3050
3. No audio output generated.(It applies both LT-30XX and LT-22XX)
Notes) This model is enabled to set up an audio input terminal for each video input terminal. No
audio output is available unless the input terminal of displayed pictures (example:VIDEO1)
coincides with that of audio (example:PC). Therefore, analysis for troubleshooting should be
carried out after the displayed video input terminal (example:VIDEO1) has been made to coincide
with the input terminal according to the instruction manual.
Enter a signal input AUDIO in.
Volume level is not 0. And MUTE is off.
YES
Is "TV speakers" setting on?
YES
In case of TV input, is "Listen To:" setting set
to Stereo or Mono?
YES
Is voltage the same before and behind F870
and F880?
YES
Are the specified voltages available at the
pins below? (Power source check)
CN
Name
S5V J303
A5V J8A0
A9V J8A0
A8V C733
AMPVCC IC711
SAMPVCC IC712
Psave2* J712
Psave3** J712
*control signal of A9V, A8V, A5V
** control signal of AMPVCC, SAMPVCC
YES
NO
NO
NO
NO
NO
Pin No. Voltage
12 5Vdc
1 5Vdc
10 9Vdc
- 8Vdc
1 7~9Vdc
1 8~12V
dc
6 3Vdc
7 3Vdc
Raise volume level. And MUTE is turned off.
"TV speakers" setting is on.
"Listen To :" setting is set to Stereo
or Mono.
It replaces the PWB-SET(SUB).
(Fuse have blown out. )
Problem is in the following
circuit (and peripheral
circuits) .
Voltage with PWB
problem including
the circuit
in problem
S5V SET(SUB)
A5V SET(SUB)
A9V SET(SUB)
A8V SET(SUB)
AMPVCC SET(SUB)
SAMPVCC SET(SUB)
Psave2 MAIN
Psave3 MAIN