Reviving an AutoDarkening Welding Helmet

Next solder the 2xAA battery holder leads. Red lead to the positive marked lead where the CR3023 battery was connected.

Then do the same procedure with the Black lead to the minus(gnd) marked lead where the CR3023 battery was connected. Cut a slot in the LCD case so that the holder leads can be routed outside the case. Hot glue the wire leads, slot, and glue cutout cover plastic you saved back into place. To break the suspense, I thought I was done at this point, but after tossing in batteries and welding, I found that the darkening attenuation at the dark-most setting of the lens was not what it used to be.

Short_tangent_rant: At this point I got on the internet and did a search to see if anyone else had tried this. I like to reason out and try things first before resorting to Google. This way I have to use my own creative muscles first, before using another person's brain power. This can be both good and bad in that often you can learn from others trial and error before doing a task, but if you always resort to others to tell you how to do things, you don't work through the "eureka" discovery process that can often lead to new and novel ways of doing things. End_Of Short_tangent_rant.

I found some links where people had found a 2nd battery on opposite side of the lens, but they couldn't explain its purpose or why it usually still had reasonable life in the battery. I can clear this up. The first battery powers the analog circuitry( op-amps etc ) that process the light levels an then control the drive to the LCD of the lens that darkens. The 2nd battery is the contrast voltage for the LCD and is responsible for how dark the lens can go. Contrast voltage to LCDs are extremely low current draw so this battery is often still usable.

Contrast voltages are sometimes negative with respect to the other circuitry and this is the case here. The two coin batteries are wired in series, with the first battery's negative connecting through the PCB to the 2nd battery's positive. This creates a bipolar supply +3vdc/-3vdc for both the analog processing and contrast circuits.

So after dremeling the case to expose and remove the 2nd battery, using the same procedure as the first battery revamp, I put in the 2nd set of AA's into the 2nd holder and mounted them inside the helmet above the lens.

I recommend to use Velcro with really good adhesive that wont slide off over time. Liquid Nails item called "Perfect Glue" in a tube is one of the best clear adhesives around. It's not Vinyl bases, but like stiffer silicone on steroids. I used coated Romex wire in a pinch to wrap them in place.