avrdude: stk500v2_ReceiveMessage(): timeout with ADDAC VCC I am getting the above error message uploading the ADDAC VCC, and the only thing that's changed I think is the patch is bigger.

Is there a fix for this or will I have to send it back? Hope my formatting is OK

Binary sketch size: 12,330 bytes (of a 258,048 byte maximum)
/usr/share/arduino/hardware/tools/avrdude -C/usr/share/arduino/hardware/tools/avrdude.conf -v -v -v -v -patmega2560 -cwiring -P/dev/ttyUSB0 -b115200 -D -Uflash:w:/tmp/build953252908946386724.tmp/comps.cpp.hex:i 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] 

avrdude: Version 6.0.1, compiled on Oct 21 2013 at 17:07:18
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2009 Joerg Wunsch

         System wide configuration file is "/usr/share/arduino/hardware/tools/avrdude.conf"
         User configuration file is "/home/luke/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyUSB0
         Using Programmer              : wiring
         Overriding Baud Rate          : 115200
avrdude: wiring_open(): releasing DTR/RTS
avrdude: wiring_open(): asserting DTR/RTS
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer

avrdude done.  Thank you.

avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14]
Your log is showing that communication is failing right away (avrdude never gets a proper response). This can mean that 


the VCC is not resetting
there is no bootloader installed 
there is some other defect


You can test case is by manually hitting the reset switch around the time that avrdude starts. If the necessary pins are available, you can exclude case 2 by installing a new boot loader with a programmer, which also tests scenario 3 a bit.