Mitsubishi SL1U Service Manual page 34

Power source system 1
The product does not
enter the stand-by mode.
Has the FUSE (F901)
blown?
PCB-INLET
YES
Does the thermal
protector work?
YES
Is the lead wire
to the RB
connector cut?
YES
Is the pin No. 8
of the SF
connector 5V?
PCB-MAIN
YES
Replace the PCB-
MAIN and check if the
product enters the
stand-by mode.
YES
Malfunction of PCB-MAIN.
Using the shielding case as GND is allowed when checking the voltage waveform or terminal voltage on the secondary side.
LED is not lit.
Check STBY5.
NO
NO
NO
Replace the lead wire.
Remove the
NO
SF connector
from the PCB-
MAIN.
NO
Malfunction of MEMBRANE
switch.
Replace MEMBRANE switch.
Check the failure on the PCB-
POWER, then replace the parts.
Reset the thermal protector
and check the dust on the
filter.
PCB-POWER
Is the pin No. 9
of the RF
connector 5V?
YES
Replace the PCB-
MAIN. Check that the
product enters the
stand-by mode.
NO
Replace the PCB-
TERMINAL. Check that
the product enters the
stand-by mode.
NO
Replace the PCB-
AUDIO. Check that the
product enters the
stand-by mode.
NO
Replace the PCB-
PREAMP. Check that the
product enters the stand-
by mode.
NO
Malfunction of MEMBRANE
switch. Replace MEMBRANE
switch.
- 2 -
thermal protector : on the lamp box
Check the circuit around
NO IC950, IC951 and PC950,
then replace the parts.
IC950 : Primary side SW-IC
PC950 : Photo coupler for feedback
IC951 : Shunt regulator for feedback
Z954, Z955 : Circuit protector
YES
Malfunction of the PCB-MAIN.
Malfunction of the PCB-TERMINAL.
YES
YES
Malfunction of the PCB-AUDIO.
Malfunction of the PCB-PREAMP.
YES