Introduction: Improving a Standard Wall-wart Power Supply.

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About: I'm mainly interested (with occasional digressions!) in working with music technology (crossing over into audio), whether acoustic, electric or electronic. I particularly like upgrading and repurposing basic o…

This idea is so simple that I'm not sure it really counts as an Instructable! However, as plug-in power supplies are used for so many things, both in the Instructables realm and in general, I thought it might be worth sharing.

While this suggestion can be applied to any such unit, including those used for phones, low-voltage lighting etc. I've parked it on the Music channel because (a) that's where I usually operate and (b) anyone making music involving electronics, from guitar effects to a synth/studio setup, will probably be using more wall-wart PSUs than most people and will equally probably have been in a situation where one of them stops working or suddenly only works intermittently, due to wear and tear and/or the unit being too cheaply made for its purpose (even high-end items of equipment are often shipped with shoddy generic PSUs).

The most frequent issue is a broken connection either within the molded barrel plug or at the other end of the cable inside the unit's casing. This is tiresome enough in the studio but can be a total evening-wrecker during a gig.

There are remedies, of course, if you happen to be handy with a soldering iron and a screwdriver. Molded plugs can't be repaired, but solderable replacement plugs can be sourced and some wall-wart casings can be dismantled to repair internal connections. This is, however, fiddly and tedious, so as often as not the whole unit is simply discarded, which is both wasteful and environmentally undesirable.

Instead, then, we're going to make some minor, non-destructive external modifications to such a unit that will prolong its useful life by making the connections at both ends of the cable much less vulnerable. While we're at it we can prevent the cable from becoming tangled in storage and we'll also attach a label to the unit. The latter is useful given that such items usually look pretty similar but are rarely interchangeable and can be hard to identify when separated from their parent devices (particularly unhelpful during the inevitable pre-gig setup scramble).

Supplies

This is all you need!

  • The PSU you want to modify. This technique will work with most models (you'll easily work out whether yours is one of the few exceptions).
  • Two narrow nylon cable zip ties (the examples shown are 1mm wide, which is ideal).
  • A plastic tag of the kind often used for identifying keys.
  • A single Velcro cable tie of suitable size. The lightweight design shown here is best, being the least bulky.

All of the mod items are obtainable from suitable suppliers (eBay will provide if you can't source them locally) for next to nothing.

The only tool you'll need is a pair of cutters or similar to snip the zip ties to length.

Step 1: Applying the Modifications.

These are so easy that we may as well deal with them all at once:

  • Remove the key ring from the tag and write the name of the PSU's designated device on the label (which I've not bothered to do here!).
  • Thread one of the zip ties through the key ring hole on the tag.
  • At the plug end, make a small loop in the cable, then use the other zip tie to attach the loop to the plug's strain relief grommet as shown.
  • Do the same at the other end of the cable, which will allow the zip tie to both grip the other strain relief grommet on the PSU's case and hold the label tag.
  • Attach the Velcro tie just above the second loop as shown.

That's it!

Step 2: Reflecting on What We Just Did!

What we've done here, of course, is redistribute the stress caused by yanking and flexing the cable in such a way that much of it is diverted to the cable loop/zip tie assembly and thus to the exterior of the strain relief grommets at both ends, rather than just relying on the grommets' molded grip on the cable sheath and hoping for the best.

The label tag idea is, I find, much more useful than the usual sticky labels, which can either come off (many plastic finishes resist label adhesive) or become scuffed to the point of illegibility. The fact that these tags come in several bright colors is also a great aid to quick identification.

I've been working my way around all my wall-wart PSUs with this procedure with very satisfactory results. In an ideal world there'd be an enterprising manufacturer producing super-rugged, gig-friendly aftermarket wall-warts, but until that happens...

(Oh, and finally, you weren't going to assume that this mod is so dramatic that it allows you to disconnect the PSU by pulling on its cable just like the manual tells you you shouldn't, were you? Thought not. : ) It does, however, reduce the chance of the cable being unplugged accidentally by partially absorbing and redirecting the force of an accidental tug, which is a useful secondary benefit.)