XOCECO LC20Y19, Service Manual

Page: 21 / 50

19
Troubleshooting charts
This series models adopt built-in power. The power to the main board may be different when the unit
adopts different panels or whether the audio amplifier is located on the main board or not. The following
is the detailed power in different cases.
Model Audio amplifier
Power socket
number on the
mainboard
Definition of the pins (as follows, PBIAS refers to
backlight ENABLE, PWM refers to backlight
brightness control signal.)
LC-20Y25
LC-20Y15 AN5277, locates on
power board, Vcc=18V X702
8 pin 1, 2: +12V 3, 4: GND 5: +3.4V
6: GND; 7: PBIAS 8: PWM
LC-15Y3 TPA1517, locates on
mainboard, Vcc=12V
X701
6 pin 1, 2: GND 3, 4: +12V
5: PBIAS 6: PWM
LC-23Y25 AN5277, single audio
amplifier, Vcc=18V
X702 1, 2, 3: +20V; 4, 5, 6: GND
7: STANDBY 8: +3.3V
LC-20Y3 AN5277, locates on
mainboard, Vcc=18V
X702 1,2: +12V 3, 4: GND 5,6: +18V
7,8: GND 9: PBIAS 10: PWM
1. No raster, no picture and no sound
When the main power is turned on, the unit’s indicator lights up in red (red indicator is controlled by
+3.3VSTANDBY), use the remote control or the unit’s STANDBY to lights up the blue indicator.
Whether the IR board’s
red indicator lights up?
Power board’s +3.3V
is abnormal
Whether the blue
indicator lights up
when press the
STANDBY button?
Confirm the IR
sensor and its power
supply is normal
Indicator damages or blue
ind9V power is
abnormal (check +9V circuit)
Whether the
backlight lights up?
Whether the voltage
of the panel is
normal?
8125 is abnormal without
signal output or the output
signal is abnormal
Whether the backlight
power or PBIAS pin is
l
Backlight board damage or protection.
Replace the backlight board
Whether the
backlight power or
PBIAS pin is normal
Check power circuit or whether the 8125
PBIAS signal is normal
N
Y
Y
Y Y
Y
N
Y
N
N