Allbot VR408 power supply issue



I probably have a power supply issue with my allbot VR408. I am using the Arduino code supplied by Velleman and 4 new Energizer alcaline batteries. The robot is working correctly only when the USB cable is connected to my laptop. When it is not connected, the arduino Mega board misbehaves and restarts all the time. Voltage measurement shows that the 12V boost voltage drops down to 4V when servos switch on and the 4 blue leds light decrease, which explains the Arduino board misbehaviour. Also, the 5-6V battery voltage drops down to 2.5V.
Could you help me with that?


I did additionnal measurement and what I said before was not exactly true. I did test with both an Arduino Uno and an Arduino Mega. The 12V boost voltage is measured at 11,9V when the VRSSM board is unplugged from the Arduino board. When connected, this voltage drops down to 4V, not enough for the Arduino board to work correctly.
There might be a problem with the voltage boost system.


Can you post a picture of the boost circuit?





The circuit looks fine