This is another sight I got at an auction, it took me a while to figure it’s the first model of the Knights Armament PVS-22.
It powers on and then you can see through the tube if you are in a bright room, or if you look at street lights at night, but otherwise it doesn’t work as a night vision.
The gain knob does make it even dimmer when turned down, but cannot make it actually work in the dark.
I contacted Knights Armament by email, but so far they have not responded.
I’ve had a few night vision devices and I’ve never seen this problem - they either work or not, never kinda maybe a bit.
I was hoping that there is something about this in the manual but it just says to turn the gain knob to dim it if needed.
What is causing this problem - the tube or the board?

bump, but I dont have an answer.

Second for reaching out to Jay, he knows I2 clip ons extremely well

I will give them a call tomorrow.
I opened the lid and peeked inside. There’s no board, just the switch. One set of wires comes in from the battery (3 in the picture) compartment, and two sets of wires go out. One attached to a ribbon (1) and the other one is just two solid wires(2).
When the ribbon is disconnected, the tube still powers on but turning the gain switch doesn’t affect it.
It’s hard to measure the voltage but I was getting very low voltage - 0.26 volts getting to the ribbon. The other set of wires was getting 2.84 volts.
I’ve only had PVS-7 units and never dealt with tubes that have ribbons - why does this thing have two sets of wires to power it?
I can’t figure how to remove the knob from the switch and maybe then remove the switch to check it, there’s no set screws or anything like that, and you have to pull it hard to turn it on.