# What Reasons Lead to The LED's Error ?



## letters109 (Mar 10, 2017)

Hello~all
I have a trouble about led,can you help me?Let me state the problems clearly.
The LPC103 I use is this,and I control ten road LED by using IO port of ten road.The source of every road led is 12V while it connected the resistance of 680 ohm and four leds.The program control the base high/low level of NPN(this) triodes to realize that the leds can open and close.However,some LEDs send weak light and they can’t be closed.I don’t know what reason lead to this problems ! Because of some special request,here has four boards which two boards belongs to signal floors and the up and bottom is cables and covers. Do you know how to solve this problems? 
All your help will appreciated!Thank you !

PS: Actually I would like to upload the picture from my computer,but I don't know how to upload it?


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