If I had three words to say, it would probably be just my luck. On 20th February this year, the Linksys PAP2T ATA that provides VoIP phone service to the house went down because of a power supply failure. Knowing that bad things can happen, I always had a spare device, but I didn’t know until I examined it closely, that my spare device was a counterfeit. Oh well, I thought. At least I can still use the power supply – so I plugged it in and the line came back up.
I always thought that this would be trouble, as people complained their counterfeit PAP2T’s error out on a red power indication, so I prudently ordered a spare power supply only for it to be lost in the mail after a few months of waiting.
Then, yesterday, the inevitable happened. The counterfeit supply decided to give in, and the PAP2T gave out the dreaded red power LED indication after a few boot loops. Another bad power supply!
Taking it Apart
This unit came with a counterfeit PAP2T, so I’m going to presume it’s a counterfeit power supply. It had a US two-blade power input which I forcibly bent to accommodate Australian sockets.
This photo was taken after the case was forcibly cracked open, showing the exterior and model number.
Well, if the cause isn’t already clear, it failed because of the same reason as the other supply – a failed capacitor on the output side. While it is potentially repairable, the case suffered quite a bit of damage in opening, and I don’t have much faith in the quality of the other components in the design. A KSD branded primary side cap? Never heard of them.
A side profile shot shows you just how shoddy the parts can be – the input filter inductor (at least they had one) has a band at the top which is badly glued out of place. Other than that, some of the rest looks okay, as it’s fused on the primary side.
A look at the underside shows the primary to secondary isolation is good as well. However, the unit was quite hot as I removed it from service, so I can’t help but think that the capacitor failure may have caused stress to the other components, so lets just bin this and buy another. Power adapters are easily exchanged …
The failed cap was a Teapo (rhymes with cheapo). While Teapo doesn’t have a stellar reputation, I’ve personally not had that many issues with Teapo caps, which leads me to believe that some of the bad caps we see venting are actually not solely a result of poor capacitors. For example, using a capacitor which was under-specced for the expected ripple current or with a lower than necessary temperature rating will overstress the capacitor, causing it to heat up, and slowly boil away.
Of course, there definitely are off-brand capacitors which are questionable on a lifetime basis, and counterfeit components as well which emulate the markings and design of quality components but without the same level of performance.
This year hasn’t been a good year for my VoIP gear – now the home PAP2T is running from the supply pinched from the SPA112 while I try to source two decent replacements without breaking the bank. I do have another PAP2T with an identical power supply to the first that failed … bought at the same time … so maybe make that three …