MacNN is reporting on an ongoing issue with older Apple Time Capsules failing in unusual numbers. MacNN's source is the Apple public discussion forum, where there is currently an 18-page thread about the failing Time Capsules.
Courtesy of Apple
After reviewing the discussion, it appears that Time Capsules just suddenly fail with no outward indication. Essentially, they behave as if there is no power, which suggests that the power supply itself is the cause of the failure. A failed power supply may or may not be the real cause. Failed chips or circuitry in the Time Capsule unit could also cause a power supply failure.
Regardless of the cause, it's important to understand that the Time Capsule's hard drive, which contains your backups, is probably in good shape, and you can probably recover the data if you move the hard drive to another device. Keep in mind that if you take a non-functioning Time Capsule to an Apple Store or authorized repair facility, Apple won't repair it if it's out of warranty, just offer to sell you a new one.
Apple should instead, at a minimum, offer to transfer the data from the old hard drive to any new Time Capsule you purchase. And if these failures are the result of a design flaw or production problem, Apple should be replacing or repairing the affected units under an extended warranty.