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Old 05-17-2006, 12:11 PM
KlondikeGeoff KlondikeGeoff is offline
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Life of AC adapter power supplies

Looked at howstuffworks.com, googled, etc and got a wealth of information about these, but not a hint of the dreaded MTBF (mean time between failure).

When I have these for printers, PDA, cell phones, etc always think that if the damn things burn out, and the device is old, probably won't be able to get a replacement, and there goes a perfectly good thing.

So, for my printers and some others, just plug them into a power strip and turn it off when not using the device.

Is this overkill? As they are nothing but transformers/converters, I think, do they really have along life?
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Old 05-17-2006, 12:41 PM
spingears spingears is offline
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Quote:
Originally Posted by KlondikeGeoff
As they are nothing but transformers/converters, I think, do they really have along life?
Probably as long as the device each one powers, barring manufacturing defects.
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Old 05-17-2006, 01:00 PM
FatBaldGuy FatBaldGuy is offline
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Also, if you have the specs from the old unit (usually printed on the unit) you should have no trouble getting a generic replacement.

There are 3 main things to consider when replacing a power supply:
  • Output voltage (usually somewhere between 6 - 12 V DC)
  • Size and shape of the power connector
  • Polarity of the power connector (positive center terminal or negative center terminal)
Many places such as Radio Shack sell transformers that have a switch to select the voltage, and have multiple adapter ends with switchable polarity.
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Old 05-17-2006, 01:38 PM
Rico Rico is offline
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Quote:
Originally Posted by FatBaldGuy
There are 3 main things to consider when replacing a power supply:
  • Output voltage (usually somewhere between 6 - 12 V DC)
  • Size and shape of the power connector
  • Polarity of the power connector (positive center terminal or negative center terminal)
No!

There are Four main things to consider when replacing a power supply:
  • Output voltage (usually somewhere between 6 - 12 V DC)
  • Size and shape of the power connector
  • Polarity of the power connector (positive center terminal or negative center terminal)
  • Current Draw (expressed in Amperes, i.e. 1.2A). Get one with insufficient current and you'll likely have a puddle of plastic goo as the adapter melts.

And NO ONE expects the Spanish Inquisition!

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Old 05-17-2006, 02:03 PM
FatBaldGuy FatBaldGuy is offline
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You're right, Rico. My bad.
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Old 05-17-2006, 02:09 PM
Kevbo Kevbo is offline
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If you have a supply with an oddball connector, you can splice the connector end of the old cord onto the cord of the new supply. Unfortunatly, one of the common failure points is right at the connector.

Proprietary connectors on such things are a pet peeve of mine.
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Old 05-17-2006, 04:59 PM
Nanoda Nanoda is offline
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I've only ever seen one burnt-out transformer, and it was due to the issue Rico reminds us about: current draw.

I was repairing a printer someone at my office was throwing away, and neglected to note that the 1.2A it required was far more than the 500mA maximum my variable transformer was capable of supplying. Now that I think about it, someone on this board mentioned mixing up transformers between speakers and external HD or something when re-assembling their PC and blowing the adapter, so I expect that might be the source of most problems here.

Like Kevbo says though - in such an unlikely event, you could splice the end on to a similar transformer with little difficulty.
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