12 Volt Power Supply Adapter Failure

This is about switching power supplies and adapters of sizes from the very large to the quite small.  These convert mains and car electricity into the correct voltage and current you need to run today’s high tech devices. These adapters power cell phones, tablets, laptops, and desktop computers.  Indeed, they power just about any IT tech gadget.  All of these gadgets need power conversion of some form to work.  But when the supply fails, look out for strange errors or no function at all.  Here we describe our experience with a 12 volt power supply adapter failure on an external hard drive. When the supply failed, the drive did not shut down all the way.  No.  It still ran, but behaved like it was going bad.

12 Volt Power Supply Adapter Failure Intro

Switching power supplies, while quite good at performing very tight voltage regulation and current overload protection, often fail; probably more so in the home electronics realms than the traditional linear, transformer-based supplies.  They contain more complicated designs and components; which is likely why their regulation is superior to linear models.  But it’s also why they’re more prone to premature breakdown.

Often, when these switch mode adapters do fail, the symptoms of the problem can appear quite strange and misleading.  Attached devices may give wrong error messages.  They could make strange noises, heat up too much, charge more slowly, and function in erratic ways.  Lights may blink or flicker, instead of simply going out.  Or, their motors may hum or whine.  In short, the device itself may seem to have broken. But in fact, it’s the power supply that’s causing the weirdness.

External hard disk drives often have power adapters. Indeed, these can fail, and can show unusual behaviors.  Here’s a scenario that happened to us some years back.

12 Volt Power Supply Adapter Failure: The Symptoms

The external hard disk drive (HDD) that we keep attached to the home PC began cycling on and off.  You could hear it spinning up and slowing down. Plus, the LED pilot lamp on the front grew brighter, then dimmer, then brighter again. Further, the drive no longer showed up in Windows Explorer. Further, it gave off these strange clicking sounds.

The Diagnosis

We have many external HDDs for our disc jockey business. Now we can’t afford to go down at a gig due to a bad power supply.  So, where affordable, we keep a few spare power supplies as well as extra HDDs. Now the power supply was the cheaper of the two devices to “swap out”. Thus we found one of the several spare 12V 2A 24W supplies in our stash.  Then, upon touching the original supply, still plugged into the power strip, it felt very warm. Excess heat is another hint that this adapter might be faulty.

So we took out the old adapter and connected up the new. Then right away, the drive spun up in a healthy fashion. Plus, the pilot lamp came on with a solidly bright glow.  Thus, we concluded that the power supply was indeed the culprit.

12 Volt Power Supply Adapter Failure: The Cure

We replaced the switching power supply thus.  At that time, we realized that we only had a few of these left.  So we decided to order a few more on eBay.

One nice thing about switching power supplies these days, is that they’re relatively inexpensive, particularly in online web sites.  So if you’re into IT type devices like us, it’s a good idea to stock up on these supplies.  Switching supplies (outside of those found in computers) have failed often here in the shop.  But perhaps over time, the technology will improve. Then, these adapters will get as reliable as the old-style, transformer-based adapters and wall warts.

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