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 Post subject: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Sun 11, 2018 4:02 pm 
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Joined: Jan Fri 08, 2016 1:19 am
Posts: 150
Location: mapleton sd
One time I saw a posting here that suggested an easy way to open a wall wart or laptop
power supply. My recollection is that it was something like painting the seam with a chemical
such as acetone, letting it set and then prying the case apart. I have a laptop power supply
that needs its cord replaced so I tried painting acetone on the seam and nothing happened.
Whatever the suggestion was that someone made here worked a year or two ago because
I tried it then and it worked great. The two halves almost fell open. Does anyone remember (or know) what chemical will break down the glue used in laptop power supplies so a guy can get inside of one?


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Sun 11, 2018 6:04 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 14172
Location: S. Dartmouth MA 02748-1225 USA
If the acetone did't work, it is possible the seam was ultrasonically welded.

If so, a possible risk destructive opening can be tried. Freeze the unit, place in gloved palm, strike the seam with a medium sized ball pien hammer (not the round side) all around the seamed area. The combination of the cold and the impact should crack the seam as the plastic is fused differently at the seam.

Wear personal protection from possible flying plastic bits.

GL

Chas

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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Sun 11, 2018 7:01 pm 
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Joined: Sep Tue 15, 2015 1:16 am
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Location: 18424 PA
Vise.


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Sun 11, 2018 9:32 pm 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 3827
Location: Florida
I just carefully cut around the seams with a small hacksaw. Haven't destroyed one yet.

RRM


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Mon 12, 2018 9:05 am 
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Location: SoCal, 91387
Easier to just use a Dremel with the cut off wheel.

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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Mon 12, 2018 4:41 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 789
Location: Pasadena CA USA
I am with fifties on this. I cut in the seam and when i put it back to together just fill the seam with epoxy. If the seam is not recessed to begin with, take a file and file a groove to fill with epoxy to make the epoxy seam level with the rest of the case.


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Mon 12, 2018 7:45 pm 
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Joined: Jan Fri 08, 2016 1:19 am
Posts: 150
Location: mapleton sd
Chas wrote:
If the acetone did't work, it is possible the seam was ultrasonically welded.
If so, a possible risk destructive opening can be tried. Freeze the unit, place in gloved palm, strike the seam with a medium sized ball pien hammer (not the round side) all around the seamed area.


Thank you Chas. That did it. I froze the laptop power supply for several hours then tapped
around its seam with a light hammer and it split apart nicely. I did this a year or so ago with a cheap Chinese-crap power supply and the stark comparison to the insides of this Hewlett Packard PS were impressive. Once inside there was an entire second case surrounding the PC board etc constructed of sheet copper. Very nice quality.

Anyway I replaced the shielded power cable that the cat chewed and am back in business.

Thanks to all for your suggestions however I tried those techniques but am now reluctant to get too involved with razor knives and hacksaws. Prior to learning about the acetone trick (and now the freeze-n-whack trick) I nearly injured myself on other power supplies and wall warts. It just wasn't worth it.


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Tue 13, 2018 12:21 am 
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Joined: Dec Tue 06, 2011 3:31 am
Posts: 90
Location: Hamilton Ontario
I usually crack them like a walnut in the vise. Usually the skinny side, and usually just half in the vise, jaws just below the seam. I tighten until they bulge. At that point, most crack open, if not, I tap with a pair of electrician's pliers.

He-he. But first, make sure that the thing isn't just held together with screws hiding under rubber feet-dots.

David


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Tue 13, 2018 12:37 am 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 3827
Location: Florida
J. Hill wrote:
I am with fifties on this. I cut in the seam and when i put it back to together just fill the seam with epoxy. If the seam is not recessed to begin with, take a file and file a groove to fill with epoxy to make the epoxy seam level with the rest of the case.


I just tape them back together as neatly as I can. Since they're on 24/7 and I keep things forever the chances of needing to get back inside is non-zero and I don't want to have to cut into them again.

RRM


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Tue 13, 2018 2:43 am 
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Retired Radio Man wrote:
J. Hill wrote:
I am with fifties on this. I cut in the seam and when i put it back to together just fill the seam with epoxy. If the seam is not recessed to begin with, take a file and file a groove to fill with epoxy to make the epoxy seam level with the rest of the case.


I just tape them back together as neatly as I can. Since they're on 24/7 and I keep things forever the chances of needing to get back inside is non-zero and I don't want to have to cut into them again.

RRM

I've got two boxfull's of wall warts, so when I open one up, I chuck the case and if I don't end up using the transformer, I simply put it in the transformer box (not to be confused with the wall wart boxes).

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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Wed 14, 2018 5:27 am 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 3827
Location: Florida
Better grab the old ones when you find them, the new switchers are useless for the kind of super duper work we do here. Another thing to hoard. :D

RRM


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Wed 14, 2018 7:55 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 18545
Location: Albuquerque, NM 87123
I use a band saw to cut through at least one side of the plastic case, then use a flat blade screwdriver to pry it open. Epoxy to put them back together.


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Thu 22, 2018 6:14 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 9993
Location: Santa Rosa, CA
I've opened dozens of them to retrieve transformers for other projects. I concur with those who use mechanical means to open them.

Using acetone might just increase the adhesive seal. You won't find a solvent that loosens the glue unless it also softens the case material. If it's a welded joint, you have to cut it.

I use a sharp wood chisel and tap along the joining seam. If you can start to break the bond, then further prying may work. I am not usually trying to save the plastic case. It's a bit like cleaving a diamond... try to find the natural break line and keep working on it. A fine blade saw will also work. I wouldn't use a bandsaw for fear of carving up the internal works. A Dremel cut-off wheel clogs pretty fast with soft plastic. It will also melt the plastic, which then solidifies and the joint doesn't open.

Image

When I go to flea markets and ham swaps, I look for the largest, heaviest wall warts (usually from printers or lawn sprinkler controllers). Some of them actually have cases held together with screws! One can immediately tell a useless "switcher" but the light weight. You can harvest capacitors and inductors from switchers, but I don't trust the electrolytics.

Rich


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Nov Thu 22, 2018 8:05 pm 
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Posts: 32973
Location: SoCal, 91387
Rich, W3HWJ wrote:
A Dremel cut-off wheel clogs pretty fast with soft plastic. It will also melt the plastic, which then solidifies and the joint doesn't open.

That's where the speed control comes in handy; just use a lower RPM. I find that the softer the material, like plastic, the lower the rotation speed, and the harder, like metal, higher to highest speed.

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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Dec Wed 12, 2018 12:33 am 
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Location: Georgia, 30236
I put one of these on my Weller soldering gun to open sealed cases on wall warts and also have done so with battery packs. It doesn't abrade the things inside and cuts through the cases cleanly, leaving the removed plastic to allow welding it back together.


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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Dec Wed 12, 2018 10:18 pm 
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Location: Port Orchard, Wa 98366
You will never have that problem again if you throw the CAT in the freezer. Just Saying. :mrgreen:

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 Post subject: Re: Opening Wall Wart or Laptop Power Supply Question
PostPosted: Apr Sat 20, 2019 3:43 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 783
Location: dayton oh usa
i use a crap beat up pocket knife whose lock failed causing a nasty cut.
now it gets beat on to crack wallwarts and battery packs.
put the edge in the seam and smack sharply.
most will open neatly enough that after the repair a thin bead of ca and a shot of zipkicker will make it look like it was never worked on.
i mark them so i dont grab one i forgot about and preemptively open it up to replace the crap caps they come with.


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