I recently resolved this issue for my friend who has a saber with
Obsidian Lite.
When swinging or moving the lightsaber, the batteries are prone to shifting in the battery pack. A quick and simple solution for this is to tape them in tightly with electrical tape. Some people also use a small piece of velcro to add some extra padding inside and stop battery movement, although with the soundboard attached there may not be enough room. This was the case for my friends Dominix v3; so we used electrical tape.
Now, for the saber turning itself off by itself, without any movement or touching... we experienced this. I found the issue to be with how the circuit is wired up; essentially the circuit was overloading the Obsidian Lite soundboard and triggering an automatic shutdown to protect itself. The issue was with the resistor provided; I fixed this issue by replacing the old resistor with a better one. (Picked up from Maplins for about 60 pence)
This is the replacement part that i fitted to resolve it -
http://www.maplin.co.uk/p/wirewound-3-watt-47-ohm-resistor-w4r7Obviously, this MAY NOT be the exact issue you are facing; but what you're describing sounds identical to an issue i fixed a little over a week ago.
If you're not confident in determining electrical faults, and soldering and repairing the electricals yourself, i'd strongly recommend contacting Ultrasabers (
and not voiding your warranty) to arrange repair for it.
Hope you can get this issue resolved!