DAYTEK LC1508NT, Service Manual

Page: 8 / 17

Trouble Shooting
Key IC list
Item Type Maker Package Circuit No. Qty.
1 TDA15001H1 Philips QFP128 N401 1
2 MST518 MSTAR PQFP160 N501 1
3 24LC32A MICROCHIP SOIC-8 N402 1
4 24LC21A MICROCHIP SOIC-8 N302 1
5 MP1410ES-SOIC-8 MPS SOIC-8 N801,N802 2
6 FDS9435A FAIRCHILD SOIC-8 N803 1
8 TDA1517 PHILIPS SIL9MPF N200 1
FSAV330 FAIRCHILD 9
(only for
KLC-1521US)
TS5V330 TI
TSSOP-16 N301,N303 2
11 1117-3.3V 1117 serial SOT223 N804,N806 2
12 1117-2.5V 1117 serial SOT223 N805 1
14 Tuner AFT1/L301 Qingjia N100 1
Start order
：
1)Verify the state of TV set.Please switch the TV on ,then verify the LED color. Red is
standby state and green is working state.
2)Checking Supply Power.If the color of LED is yellow,the power supply for signal board
。
N801 supply 5V and N802 supply 3.3V(KLC-1508US,KLC-1521US),N804 、 N806 supply 3.3V
power(Test the PIN 2).N805 supply 2.5V(Test the PIN 2),D803 supply 8.3V,V401 and V402
supply 1.8V. All these are for main IC N401,N501.
3)After turning on the power, if blank screen appears (no back light lamp), just
press POWER button several times, if blank screen still there.Check if the voltage of
every power supply is normal.
4)Check if the crystal oscillator X501(14.318180MHz) X401(24.576MHz) oscillate or not,
and oscillate frequency is right or not.
5)Back light control signal (BKLON) of XS801 has high level (about 2.5V)
or not, if not, check whether fault soldered or short circuit happened
。
6) If back light lamp is on while there is no display,check N407 and N501
’
s reset circuit
and the output of the oscillator to confirm the CPU and SCALER are working or not.If RGB
is abnormal,check N501;If RGB is working correctly and the other channel is
abnormal ,please check N501.
Turn on the
power
N401 RESET and
IO port initialize
N501
electrify,
reset, initialize
Turn on back
light lamp
Successful start
and LCD display
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