Thread: PC Power supply
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Posted to uk.d-i-y
Paul[_46_] Paul[_46_] is offline
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Default PC Power supply

Martin Brown wrote:

If you are feeling brave you could probably replace the fan in the
current unit even though officially there are no user serviceable parts
in them. To bench test a PSU check for the instructions online.

You will find a square fan inside. The fan will be of
conventional design. The outer dimensions are industry
standards, like 80mm, 120mm, 140mm. The thickness
would be 15mm (slim), 25mm (normal), 35mm (deep).
The added depth (the 35mm one) is only when huge
CFM numbers are expected, like designing a vacuum
cleaner or something.

Fan classes are low, medium, high, ultra.
Low and medium are typically used for general
computer tasks. Medium would be a choice for the
rear cooling fan on a PC (roughly 35CFM say).

The connector within the PSU, for the fan, can be
similar to a PC fan header. And you can disconnect
the fan cable from the PSU PCB relatively easily,
without touching any HV circuits in the PSU.

A replacement can be done, assuming you can match
the fan with a suitable replacement. Even the current
consumption value of the fan printed on its hub (150mA)
may hint at what class it is. For example, I have a
120x120x35mm fan that runs at 12V @ 1000mA, and
it moves 110CFM and you cannot put up with that noise
for more than a few seconds. It would be considered
an "Ultra", but that isn't printed anywhere on the
labeling. And at 35mm deep, there is no way that
would fit inside any PSU.

On ATX PSUs, there is usually a sticker over one of
the four screws in the lid, labeled "warranty void
if removed". Usually when a fan needs replacement,
you're outside the warranty, and removing the screws
is then not such a big deal. On some PSUs, the warranty
is worthless (such as when all company representatives
leave the country, and the chances of making a warranty
claim are slim).