Gallery, Projects and General > How do I??

Can the auto-darkening filter be replaced in a welding helmet?

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dwc:
So it turns out it's actually quite easy to bodge in a new battery pack.

It took me a while to figure out how the batteries were wired up as I wasn't going to risk prying the circuit board out and the power traces are on the back I think (it's all hot glued in). Eventually I figured out the batteries are in series and the top two connections provide power - my knowledge of electronics is only marginally greater than my knowledge of welding.

A little hole in the case, some bodge wires, a battery carrier and connector later and we have the frankenshade. It works better than new.

After some experimentation I've noticed that when powered by batteries the shade comes in much much faster. I was testing it against an old halogen lamp and under battery power there's no perceptible flash when the light switches on. Under solar power you get a blinding flash and then the shade cuts in, presumably this is the circuits powering up / booting as there's a surprising number of chips on this thing.

I don't know for sure but I strongly suspect the shade wasn't coming in with the old batteries present because they were forming a circuit which causes the solar panel to be disabled. I noticed when I had it hooked up to my bench power supply that the shade wouldn't come in on solar even if the power supply was off - today I also learnt that there's a path through the bench power supply, presumably through the transformer.

Anyway, thanks for your help.

Muzzerboy:
This has been an interesting thread. I didn't realise they used little rechargeable cells internally like that. I guess it helps to hang the masks in daylight rather than store them in a cupboard for instance.

I have several of these auto darkening things now. My first was one of the generic Chinesium ones that cost peanuts. I couldn't adjust it to do anything helpful, as the darkening simply seemed to shift around the window. When I got a Miller branded one at work, I realised how a proper one should behave. I then bought myself a Miller one and soon after a Lincoln one which both work as they should. I seem to have picked up another Chinesium one along the way - not sure where it came from but it works reasonably well although it doesn't seem to have the same adjustment range.

The best enhancement I made to the helmets was the purchase of the magnifying lenses. These are optional extras which fit on the inside of the window and work rather like reading glasses or those magnifying headsets. It's not so transformative for MIG work but for TIG you need a clear, closeup view of the weld zone and they made all the difference.

awemawson:
Plus one for the 'helper' magnifying lenses - a great aid!

mattinker:

--- Quote from: Muzzerboy on May 23, 2021, 08:24:08 AM ---This has been an interesting thread. I didn't realise they used little rechargeable cells internally like that. I guess it helps to hang the masks in daylight rather than store them in a cupboard for instance.

--- End quote ---

I think they charge when in use, I may be wrong but I have a feeling I read that somewhere.

Cheers, Matthew

dwc:
It's possible there are some models that recharge their battery when in use. I certainly read that while I was looking into what was wrong with mine but I also read that the batteries last about three years, there's an amazing amount of low quality information out there.

In mine the cells I pulled out where marked CR2032. As far as I can see no one makes a rechargeable cell with that marking. If they were rechargeable they would have a variety of other prefixes. Either way the cell that had gone reverse voltage was never coming back.

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