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LED doesn't light up
CN701(43)-(44) : 5V?
OK
IC501(5) : 3.3V?
OK
IC502(Vo) : 1.5V?
OK
IC201(2) 3.3V-pulse output?
(at power-on)
NG
X201 oscillating?
3.3VD 3.3VA 1.5V
u-COM
CN701
44
43
42
41
Power on
Check item
NG
• 5V power short
• PC power cable
• PC power supply
NG
• IC501
• 3.3VD power short
NG
• IC502
• 1.5V power short
OK
• IC201(2) - CN401(8) - CN402(8) - Q461 - LED -
R480
NG
• X201
• IC201
OK
• IC201
• IC202
IC201
2
8
LED
CN401
IC501
3.3VD
5
3.3VA
6
IC502
1.5V
Vo
5V
Note : When circuit number is written, check parts and soldering
including a nearby circuit.
When two or more pin mumbers are indicated by the party,
check signal-line including a nearby circuit.
Q461
LED1
8
or
LED2
CN402
CN701 (44) : 2V/div DC
IC201 (2) : 2V/div DC
LED1-R480 : 2V/div DC
0.5 s/div
5V
R480
45
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