## Troubleshooting ### 1) General The program writes information to a log file, which might contain helpful information. It is located in the cache directory, usually in `~/.cache/cpdctrl-gui`. ### 2) The Arduino/LEDD1B does not work 1) Make sure the Thorlabs LED is plugged in, turned on (turn the dial to a non-zero value) and that the switch is in the **TRIG**er position 2) Reset the Arduino by pressing the white button on the top and restart the program 3) Unplug and replug the Arduino and restart the program 4) Re-upload the code (see section "Technical Information/Arduino Code")