Opening a glued/welded wall-wart.

[G6Tanuki]

Had to do this on one recently, the flex having fatigued off at the point where it came out through the extremely hard moulded-on plastic grommet-thing.

The 2 halves of the case were welded together, but I managed to split the weld by squeezing the case in a rubber-jawed vice but with a piece of 1/4-inch diameter rod [old potentiometer spindle] laid along the weld-line on one side, so the pressure of the vice-jaws was concentrated just at the join on that side..

Tighten it up, a satisfying crack!

Swap the rod over to the other side, repeat the process, another crack! And the top cover then came off easily, allowing me to shorten the flex by a few inches, replace the grommet thing with a few layers of adhesive-lined sleeving [my nickname isn't 'Captain Heatshrink' without reason], reattach the wires, then superglue the cover back on the case.

Result! My little Vax 'Gator' cordless vacuum-cleaner, used for cleaning up wire-strippings and solder-splashes in the worskhop, is taking charge again.

[Bazz4CQJ]

Ah, those of us who worship at the shrine of high-speed minidrills would have reached for a slitting wheel to do that job.

I've done some amazing jobs with those wheels, normally about 30mm diameter. I have three minidrills, but my current favourite is the Parkside Li-ion rechargeable from Lidl; a strong contender for the position of "Best £16 I ever spent".

B

[60 oldjohn]

I have one of those old woodworking vices that slide open quick to maybe 8-10 inches. I will give it a go next time. The advantage over dremel is no material loss, and a lot quicker.

John.

[G6Tanuki]

I've got a "Middddle of Liiddle" handheld thingy with a slitting wheel, but have always found that on plastics it tends to work by melting them rather than cutting. Maybe I'm running it too fast?

The big thing about cracking the welds - as "60_oldjohn" notes - is that no material is removed/destroyed in the process, so the two halves of the case go back together cleanly with only the thinnest film of superglue along the join.

[TonyDuell]

I also like to crack them open as it minimises damage to the case. If I have to glue the case back together after the repair I normally solvent-weld the join with dichloromethane. But if there's room I'll use a plastic pillar and screws to hold the thing together.

Sometimes I re-house the 'guts' in a plastic project box, adding a mains lead and plug if necessary.

This is all for devices used in my own workshop, so approval requirements don't apply. I do make it as safe as possible, e.g. using a plastic case and/or pillar so a stray wire can't make accessible metal live.

[fetteler]

Yep, the squeezing in a vice trick works for me every time. Neat and quick.

Steve.

[Bazz4CQJ]

Originally Posted by TonyDuell

If I have to glue the case back together after the repair I normally solvent-weld the join with dichloromethane.

But surely, after using the "Middddle of Liiddle" minidrill and slitting wheel, the repair is completed using the "Middddle of Liiddle" glue gun (possibly, the best £3.50 I've ever spent) .

I've never had plastic melt on to slitting wheels, but it often seems to happen when using a burr or arbor.

B

[emeritus]

I shall try the vice method the next time I need to open a sealed unit. My usual method has involved exploring the seam with an old and rather blunt Stanley disposable craft knife to find a point where the seal is weak, followed by a couple of WWII- vintage army pen-knives to lever it apart.

[Terry_VK5TM]

I was shown that to do the vice trick, you put it in diagonally and apply pressure to opposite corners.

The result is the same though, a nice satisfying pop or crack when it seperates.

[paulsherwin]

If you don't have a suitable vice, you can often crack them open by thumping them with a rubber mallet.

[SiriusHardware]

This is my slightly more resource heavy version of Tanuki's method - two flat metal bars stuck, using double sided tape, to opposite upper right and lower left long sides of the PSU. It obviously works best on ones which are essentially rectangles, as a lot of laptop PSUs are.

Doing it this way ensures that a lot of the sideways shear force is exerted on the seam.

[Nickthedentist]

I threw a dead one into the corner of the garage where my makeshift WEEE pile is.

It hit the concrete floor and burst open... so I rescued it, repaired it (baked smoothing electrolytic) and glued it back together. Still working now (DAB radio in kitchen).

[TonyDuell]

Originally Posted by paulsherwin

If you don't have a suitable vice, you can often crack them open by thumping them with a rubber mallet.

Don't do this if the owner/customer is watching , but in an emergency you can often get into them by grabbing the leads about 30cm from the unit and swinging it onto a carpetted floor (!).

I repaired the PSU (not strictly a wall wart as it has a mains lead/plug) for a Sanyo dictating machine today. It was already coming apart and took little more force to crack it open. I then made a pillar with M3 tapped holes in the ends and drilled a hole in each case half to put it back togther again after replacing the dried-up smoothing capacitor.

[emeritus]

A couple of months ago I levered a dead Alcatel phone charger apart that had been intermittent before its demise. I had hoped it would be just a failed electrolytic, but I found an open circuit (fusible) resistor and a plastic transistor whose type I could not identify on account of the large hole in the side where the type code would have been printed. The board was charred so it went in the bin.

[winston_1]

Some interesting ideas there. I must admit I’ve always used a junior hacksaw along the seams but I shall try the vice idea next time.

[Refugee]

I normally work my way round the seam with the smallest hammer I have got with the blade from a broken flat blade screw driver.

[Phil__G]

I find sticking it in the freezer for 10 minutes makes the plastic crack more easily...