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PostPosted: September 6, 2018, 3:27 pm 
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Joined: March 30, 2011, 7:18 am
Posts: 1450
Location: central Arkansas
Back in the mid '90s I bought a used Miller(?) auto-dimming welding helmet. I got many years out of it before it quit working. New batteries didn't help, and I needed one Right Now, so I bought a cheap Harbor Freight helmet. That one worked just fine for five or six years, then quit dimming. I replaced it with another, which made it another four or five years. A few weeks ago it quit, too. I bought a much more expensive, highly-rated hood off Amazon, which turned out to be defective (took maybe a half-second to dim no matter what the settings), so I sent that back and picked up another Harbor Freight unit.

It turned out I still had the view module from the first dead Harbor Freight helmet. It has a large solar cell in the front. I thought there might be some scavengeable parts in there (I'm slowly picking up some electronics), so I determined to get them out. The manufacturer had glued the whole thing together, so I employed "destructive disassembly." Got the cell, the LCD panel, a couple of what might be photodiodes, a potentiometer with knob and pigtail, and a few other items.

The surprise, though, was the pair of coin batteries sealed inside. They were spot welded to steel straps which were soldered to a circuit board; not replaceable. And I'd wondered how the "solar" thing worked... my best guess is the solar cell, if real, doesn't do anything at all. Five or six years is about right for most applications of that type of battery.

By then I'd wrecked things thoroughly, but I still had the newer helmet; I put it outside in the sun and it started working, briefly. So there's nothing wrong with the module other than dead batteries.

The plan is to open up the module on that one more carefully, cut the spot welded batteries out with the Dremel, de-solder the stubs from the circuit board, and solder on some pigtails to run to an external battery holder. Then I'll have a spare helmet that I can change batteries in.

The manual for the new HF helmet I bought last week actually mentions the batteries, says they're non-replaceable, and they should last for five or six years... I'm pretty sure the manuals for the other helmets had nothing to say about it.

When the new helmet dies, it'll get an external battery pack too...


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PostPosted: September 6, 2018, 3:32 pm 
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Joined: March 30, 2011, 7:18 am
Posts: 1450
Location: central Arkansas
As an aside, the defective helmet I sent back had one of the big viewports, twice as big as the cheap HF helmets. My welding bench is fairly low, so it's not uncommon for me to bump my helmet against my body trying to look down at what I'm welding. I had to close my eyes to strike the arc with the defective helmet, but after that the big window was WONDERFUL. If I didn't have a week-old small-window helmet in the drawer, I'd order another big-window one right now.


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PostPosted: September 7, 2018, 1:31 pm 
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Joined: May 25, 2016, 4:37 pm
Posts: 11
Location: Philadelphia, PA
Is it possible that the "solar cell" is actually being used as a light sensor, and not a power source?


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PostPosted: September 7, 2018, 2:52 pm 
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Joined: July 17, 2008, 9:11 am
Posts: 4805
Location: West Chicago,IL
I think my HF helmet is maybe 15-20 yrs old. It is the smaller viewing area It has no replaceable batteries. It still works just fine. Maybe I got lucky.

BTW, coin batteries with welded-on PCB leads can be purchased thru DigiKey.

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“Any suspension will work if you don’t let it.” - Colin Chapman

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