Power Supply Heatsinks & Grounding

[eat411]

I had a few questions regarding powersupply modding.

Does anyone know how units like the antec phantom work to cool the
heatsinks, without causing arcing? Are other components on the
computer to avoid being connected to the (grounded?) case?
Do heat pipe technology cooling systems, like the Zalman case, require
special precautions?

I ask because I was attempting to silence the powersupply by adding
heatsink and removing the fan. Ideally I was planning on attaching the
heatsink directly to the case of the powersupply, or the computer.
After carefully reading and disregarding the safety and warranty
information on the unit, i opened my power supply (200W?) I attached a
huge piece of aluminum to the existing heat sinks, and powered up the
unit. At this point I 'wiggled' the additional aluminum, to try for a
better contact, and had it touch the power supply case. This caused a
great arc, and a fry a PCB.

 

[kony]

I had a few questions regarding powersupply modding.

Does anyone know how units like the antec phantom work to cool the
heatsinks, without causing arcing? Are other components on the
computer to avoid being connected to the (grounded?) case?
Do heat pipe technology cooling systems, like the Zalman case, require
special precautions?

I ask because I was attempting to silence the powersupply by adding
heatsink and removing the fan. Ideally I was planning on attaching the
heatsink directly to the case of the powersupply, or the computer.
After carefully reading and disregarding the safety and warranty
information on the unit, i opened my power supply (200W?) I attached a
huge piece of aluminum to the existing heat sinks, and powered up the
unit. At this point I 'wiggled' the additional aluminum, to try for a
better contact, and had it touch the power supply case. This caused a
great arc, and a fry a PCB.

One of the heatsinks usually has a high voltage, the other
is grounded already.

Other components in a computer ARE connected to ground, that
is not a problem if/when that portion of the component is
meant to (or allowed to) be mounted to the case.

Generally speaking it's better to use a very low RPM fan
than no fan. If there is enough room in you 200W PSU to
attach longer pices of metal, it seems to be a full PS2
sized power supply, not a mATX or some other more
proprietary form-factor?

If it's full sized PS2 you might be better off simply using
a different power supply with higher capacity, THEN reducing
the fan RPM.

There are no special precautions necessary for a heat pipe
cooler, except the same as with non-heatpiped, that it's
metal and will conduct electricity so that must be
considered. I've not examined an Antec Phantom but suspect
that it simply doesn't have the heatsink connected to high
voltage and has electrically insulating pads, and washers on
the screws mounting the parts.

You might want to be more cautious inside a live power
supply, it is generally not a good idea to modify one if
you're not already aware of the issues.

 

[CBFalconer]

.... snip ...

I ask because I was attempting to silence the powersupply by adding
heatsink and removing the fan. Ideally I was planning on attaching the
heatsink directly to the case of the powersupply, or the computer.
After carefully reading and disregarding the safety and warranty
information on the unit, i opened my power supply (200W?) I attached a
huge piece of aluminum to the existing heat sinks, and powered up the
unit. At this point I 'wiggled' the additional aluminum, to try for a
better contact, and had it touch the power supply case. This caused a
great arc, and a fry a PCB.

Sounds like you need a schematic of the PS together with some
practical experience with electricity and the dangers therein.
These things are not lumps of plasticine. They will normally have
something like 250 V present, directly driven by the power plug.

 

[Guest]

I had a few questions regarding powersupply modding.

Does anyone know how units like the antec phantom work to cool the
heatsinks, without causing arcing? Are other components on the
computer to avoid being connected to the (grounded?) case?
Do heat pipe technology cooling systems, like the Zalman case,
require special precautions?

I ask because I was attempting to silence the powersupply by
adding heatsink and removing the fan. Ideally I was planning
on attaching the heatsink directly to the case of the
powersupply, or the computer. After carefully reading and
disregarding the safety and warranty information on the unit,
i opened my power supply (200W?) I attached a huge piece of
aluminum to the existing heat sinks, and powered up the unit.
At this point I 'wiggled' the additional aluminum, to try for a
better contact, and had it touch the power supply case. This
caused a great arc, and a fry a PCB.

See http://repairfaq.ece.drexel.edu/sam/smpsfaq.htm for more
information and safety precautions about power supplies.

Even a small amount of air flow makes heatsinks work much better, and
the tests of fanless supplies done by www.silentpcreview.com indicates
they run very hot unless their efficiency is higher than normal, about
85% for Antec's, verses 70% for typical fan-equipped supply (twice as
much heat).

One of the heatsinks has low voltage components attached to it, the
other high voltage components, and I strongly suggest you avoid doing
anything with the latter, especially since it's often connected to 170
volts DC for RF reduction (typical of fan-equipped Antecs). But even
if it has no voltage on it, you want to keep it completely isolated
from the rest of the power supply and at least 1/8" away from the power
supply case, on the chance that a thin insulator for a transistor
fails.

Never open a power supply except with its power cord removed, and even
then you must measure the DC voltage between its case and components
like the transistors and heatsinks before touching anything.

Your supply may have failed because of a blown fuse or shorted high
voltage transistor(s). This is a simple, usually inexpensive repair,
but don't attempt it unless you know how to work on high voltage
electronics.