user22946: I bought this Chinese Arduino Mega 2560 16AU.
This was the first time to deal with Arduino boards. When I try to upload a sketch I always get this error:
stk500v2_getsync(): timeout communicating with programmer
I successfully burnt a bootloader to it using an Arduino uno,
but the same error is there.
Finally I discovered the the loop test is not working, and only the LX LED flashes once  when I enter a letter in the serial monitor. 

user4143: It's our old friend the CH340G again, isn't it? 
You've been sold a dud, I'm afraid. The USB chip used there is dead. It happens a lot with those cheap Chinese boards. You should still be able to use the board with an external FTDI adapter by wiring it in to TX->RX, RX->TX and DTR->RESET (via a 100nF capacitor) with power and ground connected of course.
There is also a slim chance that the CH340G may interfere with the TX/RX pins, in which case you may need to remove it. Simply cutting the pins on it with an xacto knife then removing the stumps with a soldering iron and tweezers would do the job.

22946: <p>I bought <a href="http://www.aliexpress.com/item/MEGA-2560-R3-ATmega2560-R3-AVR-USB-board-Free-USB-Cable-for-Arduino-2560-MEGA2560/32437126167.html" rel="nofollow">this Chinese Arduino Mega 2560 16AU</a>.</p>

<p>This was the first time to deal with Arduino boards. When I try to upload a sketch I always get this error:</p>

<p><code>stk500v2_getsync(): timeout communicating with programmer</code></p>

<p>I successfully burnt a bootloader to it using an Arduino uno,<br>
but the same error is there.</p>

<p>Finally I discovered the the loop test is not working, and only the LX LED flashes once  when I enter a letter in the serial monitor. </p>
 4143: <p>It's our old friend the CH340G again, isn't it? </p>

<p>You've been sold a dud, I'm afraid. The USB chip used there is dead. It happens a lot with those cheap Chinese boards. You should still be able to use the board with an external FTDI adapter by wiring it in to TX->RX, RX->TX and DTR->RESET (via a 100nF capacitor) with power and ground connected of course.</p>

<p>There is also a slim chance that the CH340G may interfere with the TX/RX pins, in which case you may need to remove it. Simply cutting the pins on it with an xacto knife then removing the stumps with a soldering iron and tweezers would do the job.</p>
