How do you break open wall warts and brick type PSUs?

[dog80]

I've recently repaired a "wall wart" type PSU from a Netgear router and a brick style PSU from a Philips TV. Both repairs were very easy, just a bad cap replacement.

But the problem was getting the damn things open. After a lot of trying to pry them open with a screwdriver, I ended up sawing the plastic housing along the "seam" in the middle using a hand saw. When I was finished, I used tons of hot glue to patch them back up together.

Although they both work now, the end result is ugly and messy and I fear the hot glue might come apart eventually. I wonder, is there a better way to crack these PSUs open?

[Monkeh]

Grab opposite corners in a vice and tighten until you start to hear the glue crack. Grab the other corners, do the same. Then it should pop open easily enough. Superglue down the edges and secure in the vice to seal it up again (and be gentle with it afterwards).

[mariush]

Now that I know, I would probably try the vice and tighten the sides until they crack.

I used to get get a razor blade and pliers and go in the kitchen. Grabbed the razor blade with the pliers, heat up the razor blade tip in the fire until it's red hot, then drag the blade across the seam/margin/whatever.
It looked ugly, the plastic smells a lot... wouldn't do it today.

[digsys]

Another method I use is to - secure it to a hard surface, place a hard sharp metal strip along one seam-line. Whack it with a hammer,
start light first. Try to determine which half has the lip, the idea is to hit it at the seam. The plastic is a bit flexible, the glue isn't as much.
You can lightly heat the seam as well, first.
PS: DO all 4 sides

[Bored@Work]

Some cheap wall warts still have a screw. Typically it is hidden behind the sticker with all the fake safety marks and exaggerated rating.

[Psi]

For laptop powerpacks they're often quite thick and glued very well around a solid metal cage.
I normally dremel a 2mm grove around the seam on all sides and then use a large flathead screwdriver to crack the glue by twisting it inside the grove.

Once the repair is done i fill the grove with hot glue and a few loops of black insulation tape.

[SeanB]

What works well is to heat it with a hot air gun until it is at around 70C, then gently prise the case apart. The heat softens the glue or solvent welds used so that they will fracture easily. Then while the plastic is still hot smooth the marks back to a smooth finish.

[kripton2035]

this works fine, eventually with a hammer to open really hard cases.
http://dx.com/p/stainless-steel-metal-spudger-for-opening-watches-and-electronics-19279

[cwalex]

this works fine, eventually with a hammer to open really hard cases.
http://dx.com/p/stainless-steel-metal-spudger-for-opening-watches-and-electronics-19279

I 2nd that. I have several this and they are great for when you can't get a plastic spudger to do tho job with breaking the plastic spudger.

[mikeselectricstuff]

The method I use is to get a medium sized screwdriver with a lumpy handle, like this

Hold it near the end of the blade, hold the victim loosely in the  other hand and repeatedly hit it at the join, working all the way around, gradually increasing the force until you hear the sound change, indicating the seam has cracked. Once you get the first crack you can then usually progressively open it up using with  the  same method.
Most times this will seperate the two halves cleanly at the join, and they can be glued back again afterwards if required. .

 This method also works well on most battery packs.

[firewalker]

Most of the time I use an adjustable cutter (the ones with safety). Just couple of millimeters of the tip. I find very effective across the seam.



Something like the one below could be also effective.



http://www.instructables.com/id/PCB-cutter-tool/

Alexander.

[saturation]

Many of them use thermoplastic welds that are too soft to pry apart.  I find a dremel tool with a cutting wheel makes the best cut, works on nearly all variants of wall wart construction and gives the user best control.  The old ones  made with much more brittle plastic and those were easy to pry open, but rather than figure it out the dremel will zip through any of them.

[steve30]

I just use a combination of screwdrivers and knives to force them open.

Something like a dremel would probably be a lot better.

[G7PSK]

Use a Stanley knife blade held onto the seam with a pair of pliers and tap the top of the blade with a hammer, work all around the seam until the unit pops open.

[mikeselectricstuff]

Many of them use thermoplastic welds that are too soft to pry apart. 

This is why my hitting method works - the sudden impact fractures the weld.

[saturation]

I've seen that impact method somewhere on youtube, is quicker and easier, but any concerns of destroying items inside the PSU, assuming its for repair rather than salvage?

Many of them use thermoplastic welds that are too soft to pry apart. 

This is why my hitting method works - the sudden impact fractures the weld.

[mikeselectricstuff]

I've seen that impact method somewhere on youtube, is quicker and easier, but any concerns of destroying items inside the PSU, assuming its for repair rather than salvage?

Many of them use thermoplastic welds that are too soft to pry apart. 

This is why my hitting method works - the sudden impact fractures the weld.

I've never seen internal damage - the trick is to deliver a fast shock to the plastic, not a heavy blow. The plastic will absorb much of the force by deflecting slightly. Something like a screwdriver handle is lighter than, say, a hammer, and also doesn't mark the surface.

[Jon Chandler]

Be sure to check for screws before you try to crack/break/cut it apart. <== (voice of experience!)

[saturation]

Thanks mike, here's what I think I saw and he uses a vise or slip joint pliers and the case fractures along the weld lines:

I've seen that impact method somewhere on youtube, is quicker and easier, but any concerns of destroying items inside the PSU, assuming its for repair rather than salvage?

Many of them use thermoplastic welds that are too soft to pry apart. 

This is why my hitting method works - the sudden impact fractures the weld.

I've never seen internal damage - the trick is to deliver a fast shock to the plastic, not a heavy blow. The plastic will absorb much of the force by deflecting slightly. Something like a screwdriver handle is lighter than, say, a hammer, and also doesn't mark the surface.

[ftransform]

Most of the time I use an adjustable cutter (the ones with safety). Just couple of millimeters of the tip. I find very effective across the seam.



Something like the one below could be also effective.



http://www.instructables.com/id/PCB-cutter-tool/

Alexander.

I cut my hand bad doing this. Now I just use a hammer.

[Psi]

Speaking of box cutters.  I think china have moved to the laser sharpening method for even cheap blades.

Last month we found 5 cheap looking box cutters included inside the box of an RC plane a mate bought from hobbyking.
He didn't buy the cutters, they just came for free in the box.

But... DAMN they are sharp. I mean really sharp. like a top quality razor blade.

We both accidentally cut ourselves a little just by making slight contact with the blade.

[Monkeh]

Thanks mike, here's what I think I saw and he uses a vise or slip joint pliers and the case fractures along the weld lines:

That's exactly the method I use. Funnily enough, taught by the same old geezer on IRC.