Power supply EXPLOSION

Long thread, more an adventure, some points to note:

Industrial fanless SMPS involve managing the thermal risk:
o Primary failure of SMPS is primary-side electrolytic capacitors overheating
---- capacitors have E-S-R, Effective-Series-Resistance - higher resistance = hotter
o So for fanless you tend to 1) choose low-ESR capacitors & 2) higher temp rating
---- temp rating of PC PSUs tends to be 85oC, industrial fanless 105oC or 125oC
---- realise even Panasonic Extended Life 125oC are just 3,000hrs at 125oC

Industrial fanless SMPS range from open-frame to DIN-rail to 3-phase units.
They also, uniquely, allow daisy-chaining of outputs very often - so you can either
1) boost the power capability or 2) use redundancy to distribute load & boost life.

There are 2 general types of PC fanless SMPS:
o Those that are a modified production design
---- typically using heatpipes, hopefully low ESR capacitors & higher temp capacitors
---- identifiable by whacking big heatsink stuck on the rear, or such like
o Those that are actual industrial units - starting at a whopping £170, US$200
---- these can have 1,000,000hr MTBF incidentally
---- identifiable by "alloy frame, mesh over top & oddball expensive connectors"

Actual industrial fanless units run hot AND have a output derating based on temp.

To create your own PC fanless SMPS involves risk:
o Water cooling the MOSFETs is typically done
o That still leaves thermal output by Transformer, Capacitors, Coils & Load Resistors
o So the issue then is will convection cool those components sufficiently

So it's Make or Buy:
o Make - consider the Cost, Development, Piloting & Failure of your design
o Buy - consider the cost of an Off-The-Shelf design someone tested to CE approval

For a Bedroom-PC, fanless-SMPS, I'd always go for the Buy option.

Personally, if you do decide to modify your PSU:
o Consider running a 12V fan at say 5V
---- to cool transformer, coil, capacitors & sundry components
o Consider using a heatsink-with-internal-water-path
---- these solutions tend to leak least
o Consider turning the PSU upside down
---- so gravity pulls water away from 300V DC & transformers
o Consider using a temperature controlled fan
---- PAPST 8412MV line has a model of very low dB(A) - and cfm :-)
---- if something starts to cook - it will at least compensate for it

Usual note re primary MOSFET tabs needing insulatory pads,
since the tabs are often live - some run the heatsinks live also.

You could replace the primary capacitors with 105oC or 125oC
low-ESR units, but there are other thermal risks in a PSU.

Not many home ambient environments are below about 15dB(A).
So running a low-noise fan at 6-7V for transformer/coil/caps is not
a bad idea - leave purity of design to Architects & clients with money.

Remember relying on convection to cool a PSU ignores one problem:
o The PSU will convect ok - it has a heat source inside it & thro-path
o Cooling is dependent on delta - between PSU inlet & outlet air
o PSU inlet air is heated by convective cooled PC components
---- your HD dissipates 6-20W
---- your Optical drive 12-20W
---- your CPU VRM & RAM VRM 30-40W
---- your CPU VRM *CAPACITORS* dissipate plenty too
---- same with graphics card RAM, to your RAM chips too
o Ambient can thus easily be 30oC in a hot summer

So think carefully of your design - and it's implementation.

There are other ways of going fanless:
o DC-to-DC convertors exist capable of delivering 200W
o Use a single-output high-wattage fanless industrial PSU

You may have to double up such a solution re CPU-draw,
so one powers your hard-drives, optical-drives & such. It
is also important to verify the convertor rail capability also.
--
Dorothy Bradbury

On Fri, 23 Jul 2004 12:15:53 +0100, "Peter Hucker"
wrote:

On 23 Jul 2004 01:53:04 -0700, do_not_spam_me wrote:

"Peter Hucker" wrote in message news:opsbh8amiiaiowgp@blue...
On 21 Jul 2004 13:21:24 -0700, do_not_spam_me wrote:

In the process of testing the water cooling, did you put a
temperature probe on each of the power components?

Transformer saturation is a big concern among power supply
designers, and heat makes them saturate at lower power
levels.

I checked the heatsink temperatures with my finger.

Did you measure the voltage on the heatsink before you did this, in
case it had 170VDC riding on it?

The heatsink that was bolted the the earthed PSU chassis? No. Otherwise I would have done, as banging my head on the underside of the desk when I got a shock would not be very nice! Besides which, I'd be passing 170 volts through the water cooling system to the CPUs!


That's (the grounded one bolted to the earthed chassis) not the
heatsink that often has 170V on it, the other one is.


Didn't think anything else would need it.

Haven't you ever noticed how other transformers, including those
inside AC wall adapters, sometimes run very hot? Even the filter
inductors on the outputs of an ATX supply run so hot that temperature
sensors are sometimes mounted on them for fan speed vs. temperature
control or for thermal shutdown.

I found one hot inductor/coil/transformer/whatever it is (just two wires to it) that was warm, I put a passive heatsinnk on that and it kept it at less than doby temperature.

How does one put a heatsink on an inductor not designed for one?


75% to me sounds rediculously low, but then I don't know much about the design of switched modes. I thought switched modes gave of a lot less heat than the old ones?

They are more efficient... 75% would be higher efficiency than
typical switchless versions, but switching supplies usually
aren't 75% either... Generally the better are guaranteed to be at
least 65%, and percentage efficiency goes up as max capacity is
reached (which isn't necessarily a good thing, pushing a PSU to
max capacity) but still efficiencly may not go over 70%. If
yours was getting 75% *in use* you could consider it very
efficient for a PC power supply.


Fans can be made almost silent by balancing them and mounting them on
shock absorbers. Balancing can be done by sticking a small piece of
copper or steel tape on the fan at the exact right location, but
finding that location can require patience, unless you build a strobe
light balancer. At the very least, have a fan that automatically
comes on if the temperature gets too hot. It won't make nearly as
much noise as 15 explosions.

I have actually got a thermostat here and some large fans to try this with. If they come on a lot, or are too loud at 5 volts, then perhaps I'll go and buy some panaflows which Kony claims are very quiet.

Good fans, particularly 80mm and larger, are balanced at factory,
should not need rebalanced. If a fan is allowed to run until the
bearing dries out there may be wobble that can't be overcome with
rebalancing, but at that point the issue is one of whether fan
"really" needs to be reused after having worn the bearing instead
of being replaced. Again it is not seen nearly as often with
good quality fans that were properly balanced.

Whether a fan runs well at 5V can also depend on it's initial
speed, if you wish to use a fan you already have, try several at
5V, not just one before giving up and buying more fans. In
addition to Panaflo the NMB fans are also good at 5V, but are
slightly noisier due to their ball-bearing (but that ball
bearing(s) make them better for high-heat areas like a low flow
PSU exhaust.

On Fri, 23 Jul 2004 22:10:24 GMT, kony wrote:

On Fri, 23 Jul 2004 12:15:53 +0100, "Peter Hucker"
wrote:

On 23 Jul 2004 01:53:04 -0700, do_not_spam_me wrote:

"Peter Hucker" wrote in message news:opsbh8amiiaiowgp@blue...
On 21 Jul 2004 13:21:24 -0700, do_not_spam_me wrote:

In the process of testing the water cooling, did you put a
temperature probe on each of the power components?

Transformer saturation is a big concern among power supply
designers, and heat makes them saturate at lower power
levels.

I checked the heatsink temperatures with my finger.

Did you measure the voltage on the heatsink before you did this, in
case it had 170VDC riding on it?

The heatsink that was bolted the the earthed PSU chassis? No. Otherwise I would have done, as banging my head on the underside of the desk when I got a shock would not be very nice! Besides which, I'd be passing 170 volts through the water cooling system to the CPUs!


That's (the grounded one bolted to the earthed chassis) not the
heatsink that often has 170V on it, the other one is.

Hmmmmm, it didn't in this case. Anyway my finger was on it to test heat before I put the water sink on.

Didn't think anything else would need it.

Haven't you ever noticed how other transformers, including those
inside AC wall adapters, sometimes run very hot? Even the filter
inductors on the outputs of an ATX supply run so hot that temperature
sensors are sometimes mounted on them for fan speed vs. temperature
control or for thermal shutdown.

I found one hot inductor/coil/transformer/whatever it is (just two wires to it) that was warm, I put a passive heatsinnk on that and it kept it at less than doby temperature.

How does one put a heatsink on an inductor not designed for one?

It was a large square metal cased one. Looked like a standard transformer shape.

75% to me sounds rediculously low, but then I don't know much about the design of switched modes. I thought switched modes gave of a lot less heat than the old ones?

They are more efficient... 75% would be higher efficiency than
typical switchless versions, but switching supplies usually
aren't 75% either... Generally the better are guaranteed to be at
least 65%, and percentage efficiency goes up as max capacity is
reached (which isn't necessarily a good thing, pushing a PSU to
max capacity) but still efficiencly may not go over 70%. If
yours was getting 75% *in use* you could consider it very
efficient for a PC power supply.

Hmmmm, looking at some "requirements for good PC PSUs" I saw somewhere, it seemed tro suggest that the efficiency was LESS at higher power - it said something like "effieiency shoul be at least 75%, and 80% for half load."

Fans can be made almost silent by balancing them and mounting them on
shock absorbers. Balancing can be done by sticking a small piece of
copper or steel tape on the fan at the exact right location, but
finding that location can require patience, unless you build a strobe
light balancer. At the very least, have a fan that automatically
comes on if the temperature gets too hot. It won't make nearly as
much noise as 15 explosions.

I have actually got a thermostat here and some large fans to try this with. If they come on a lot, or are too loud at 5 volts, then perhaps I'll go and buy some panaflows which Kony claims are very quiet.

Good fans, particularly 80mm and larger, are balanced at factory,
should not need rebalanced.

I have 4 90mm fans which I can just hear when outside the case all running at 5 volts. So 2 inside should be noiseless (I'll probably hear the 4 7200rpm drives above them).

If a fan is allowed to run until the
bearing dries out there may be wobble that can't be overcome with
rebalancing, but at that point the issue is one of whether fan
"really" needs to be reused after having worn the bearing instead
of being replaced. Again it is not seen nearly as often with
good quality fans that were properly balanced.

Whether a fan runs well at 5V can also depend on it's initial
speed, if you wish to use a fan you already have, try several at
5V, not just one before giving up and buying more fans.

I have 6 spare 90mms, 2 wouldn't start at 5 - they required 7, at which point they made noise. These are all out of (ancient) PSUs - from 386 era, but I don't think they were used much.

In addition to Panaflo the NMB fans are also good at 5V, but are
slightly noisier due to their ball-bearing (but that ball
bearing(s) make them better for high-heat areas like a low flow
PSU exhaust.

How are sleeve bearings made? Sounds like a dodgy setup to me - what's to stop the sleeve wearing?



--
*****TWO BABY CONURES***** 15 parrots and increasing http://www.petersparrots.com
93 silly video clips http://www.insanevideoclips.com
1259 digital photos http://www.petersphotos.com
Served from a pentawatercooled dual silent Athlon 2.8 with terrabyte raid

What does Michael Jackson like about twenty-eight year olds?
The fact that there are twenty of them.

On Sat, 24 Jul 2004 02:22:12 +0100, "Peter Hucker"
wrote:

On Fri, 23 Jul 2004 22:10:24 GMT, kony wrote:

On Fri, 23 Jul 2004 12:15:53 +0100, "Peter Hucker"
wrote:

On 23 Jul 2004 01:53:04 -0700, do_not_spam_me wrote:

"Peter Hucker" wrote in message news:opsbh8amiiaiowgp@blue...
On 21 Jul 2004 13:21:24 -0700, do_not_spam_me wrote:

In the process of testing the water cooling, did you put a
temperature probe on each of the power components?

Transformer saturation is a big concern among power supply
designers, and heat makes them saturate at lower power
levels.

I checked the heatsink temperatures with my finger.

Did you measure the voltage on the heatsink before you did this, in
case it had 170VDC riding on it?

The heatsink that was bolted the the earthed PSU chassis? No. Otherwise I would have done, as banging my head on the underside of the desk when I got a shock would not be very nice! Besides which, I'd be passing 170 volts through the water cooling system to the CPUs!


That's (the grounded one bolted to the earthed chassis) not the
heatsink that often has 170V on it, the other one is.

Hmmmmm, it didn't in this case. Anyway my finger was on it to test heat before I put the water sink on.

Didn't think anything else would need it.

Haven't you ever noticed how other transformers, including those
inside AC wall adapters, sometimes run very hot? Even the filter
inductors on the outputs of an ATX supply run so hot that temperature
sensors are sometimes mounted on them for fan speed vs. temperature
control or for thermal shutdown.

I found one hot inductor/coil/transformer/whatever it is (just two wires to it) that was warm, I put a passive heatsinnk on that and it kept it at less than doby temperature.

How does one put a heatsink on an inductor not designed for one?

It was a large square metal cased one. Looked like a standard transformer shape.

75% to me sounds rediculously low, but then I don't know much about the design of switched modes. I thought switched modes gave of a lot less heat than the old ones?

They are more efficient... 75% would be higher efficiency than
typical switchless versions, but switching supplies usually
aren't 75% either... Generally the better are guaranteed to be at
least 65%, and percentage efficiency goes up as max capacity is
reached (which isn't necessarily a good thing, pushing a PSU to
max capacity) but still efficiencly may not go over 70%. If
yours was getting 75% *in use* you could consider it very
efficient for a PC power supply.

Hmmmm, looking at some "requirements for good PC PSUs" I saw somewhere, it seemed tro suggest that the efficiency was LESS at higher power - it said something like "effieiency shoul be at least 75%, and 80% for half load."

Fans can be made almost silent by balancing them and mounting them on
shock absorbers. Balancing can be done by sticking a small piece of
copper or steel tape on the fan at the exact right location, but
finding that location can require patience, unless you build a strobe
light balancer. At the very least, have a fan that automatically
comes on if the temperature gets too hot. It won't make nearly as
much noise as 15 explosions.

I have actually got a thermostat here and some large fans to try this with. If they come on a lot, or are too loud at 5 volts, then perhaps I'll go and buy some panaflows which Kony claims are very quiet.

Good fans, particularly 80mm and larger, are balanced at factory,
should not need rebalanced.

I have 4 90mm fans which I can just hear when outside the case all running at 5 volts. So 2 inside should be noiseless (I'll probably hear the 4 7200rpm drives above them).

If a fan is allowed to run until the
bearing dries out there may be wobble that can't be overcome with
rebalancing, but at that point the issue is one of whether fan
"really" needs to be reused after having worn the bearing instead
of being replaced. Again it is not seen nearly as often with
good quality fans that were properly balanced.

Whether a fan runs well at 5V can also depend on it's initial
speed, if you wish to use a fan you already have, try several at
5V, not just one before giving up and buying more fans.

I have 6 spare 90mms, 2 wouldn't start at 5 - they required 7, at which point they made noise. These are all out of (ancient) PSUs - from 386 era, but I don't think they were used much.

Certainly it can very per specific power supply the fan was taken
from, but in general the odds seem higher that such old PC power
supplies would have sleeve bearing... if so, they may be quieter
if relubed. Same goes for newer sleeve-bearing fans,
particularly generics. Higher-end fans like Papst or Panaflo
don't need it. The more play there is in the bearing, the more
beneficial it is to use a higher-viscosity lube, bordering on
light grease.

I find (my) ideal to be a mix of synthetic motor oil and
synthetic grease, barely thick enough that it's drop-point is
above room temp. This may be overkill for many uses but I make a
valiant attempt to refurb parts in an effort to be green, and so
far have seen no greater failure rate for relubed fans than new,
perhaps even lower rate but it could take a few more years of
service to be certain about that.


In addition to Panaflo the NMB fans are also good at 5V, but are
slightly noisier due to their ball-bearing (but that ball
bearing(s) make them better for high-heat areas like a low flow
PSU exhaust.

How are sleeve bearings made? Sounds like a dodgy setup to me - what's to stop the sleeve wearing?

Powdered bronze impregnated with oil. If they are high-precision
and the blade/hub assmbly is well balanced they will provide a
fine service life providing ambient temp is moderate, and they
are mounted in a horizontal position. Ball bearings are
preferred for non-horizontal due to their preloading (should have
small spring inside bearing cavity or on shaft). The primary
problem with them is when a poor quality fan is used in the
higher ambient temp environment, particularly video cards and
power supply exhausts. Hopefully they'll be quiet loud prior to
failure but once they sieze it's the worst possible situation, a
pleasantly quiet PC due to it not spinning-up at all when turned
on, and parts bake, similar to situation you saw with the
water-cooled PSU... maybe worse but can depend on overall case
pressurization, how much air the other fans force through the
power supply.

Panaflo (Panasonic) has tweaked the sleeve-bearing design a bit
but also they use a larger shaft than many.

http://www.panasonic.com/industrial/...anfeatures.pdf

On 23 Jul 2004 01:53:04 -0700,
(do_not_spam_me) put finger to keyboard and composed:

I believe a test of one done by www.silentpcreview.com was not very
enthusiastic, probably because the company simply took the same basic
65-75% efficiency design that's been in PCs since 1980 and tried to
make it fanless by merely enlarging the heatsinks and adding more vent
holes. They should have instead raised the efficiency to around
85-90% because such supplies are common for non-PC purposes. The best
I've seen was 96%, but it was expensive.

I wonder if this figure of 96% was for a high voltage PSU that was
optimised for a fixed load. AFAICS, the efficiency of a low voltage
PSU would be limited by the Schottky rectifiers on the load side. For
example, a 3.3V supply would be limited in efficiency to 3.3 / (3.3 +
0.6) = 85%. I suppose higher efficiencies could be achieved with high
current, stud mounted rectifiers with lower forward voltage drops, but
these would be very expensive (?).


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

On Sat, 24 Jul 2004 04:19:15 GMT, kony wrote:

On Sat, 24 Jul 2004 02:22:12 +0100, "Peter Hucker"
wrote:

On Fri, 23 Jul 2004 22:10:24 GMT, kony wrote:

On Fri, 23 Jul 2004 12:15:53 +0100, "Peter Hucker"
wrote:

On 23 Jul 2004 01:53:04 -0700, do_not_spam_me wrote:

Fans can be made almost silent by balancing them and mounting them on
shock absorbers. Balancing can be done by sticking a small piece of
copper or steel tape on the fan at the exact right location, but
finding that location can require patience, unless you build a strobe
light balancer. At the very least, have a fan that automatically
comes on if the temperature gets too hot. It won't make nearly as
much noise as 15 explosions.

I have actually got a thermostat here and some large fans to try this with. If they come on a lot, or are too loud at 5 volts, then perhaps I'll go and buy some panaflows which Kony claims are very quiet.

Good fans, particularly 80mm and larger, are balanced at factory,
should not need rebalanced.

I have 4 90mm fans which I can just hear when outside the case all running at 5 volts. So 2 inside should be noiseless (I'll probably hear the 4 7200rpm drives above them).

If a fan is allowed to run until the
bearing dries out there may be wobble that can't be overcome with
rebalancing, but at that point the issue is one of whether fan
"really" needs to be reused after having worn the bearing instead
of being replaced. Again it is not seen nearly as often with
good quality fans that were properly balanced.

Whether a fan runs well at 5V can also depend on it's initial
speed, if you wish to use a fan you already have, try several at
5V, not just one before giving up and buying more fans.

I have 6 spare 90mms, 2 wouldn't start at 5 - they required 7, at which point they made noise. These are all out of (ancient) PSUs - from 386 era, but I don't think they were used much.

Certainly it can very per specific power supply the fan was taken
from,

I used the 0 and 5V rails from the PC PSU.

but in general the odds seem higher that such old PC power
supplies would have sleeve bearing...

I think they were even marked as "quiet" PSUs. From Viglen PCs (very quiet in that era) I think.

if so, they may be quieter if relubed. Same goes for newer sleeve-bearing fans,
particularly generics. Higher-end fans like Papst or Panaflo
don't need it. The more play there is in the bearing, the more
beneficial it is to use a higher-viscosity lube, bordering on
light grease.

I find (my) ideal to be a mix of synthetic motor oil and
synthetic grease, barely thick enough that it's drop-point is
above room temp.

I've got some motor oil, and some grease for the car's driveshaft - a mix of these two? Is the grease on it's own too thick?

This may be overkill for many uses but I make a
valiant attempt to refurb parts in an effort to be green, and so
far have seen no greater failure rate for relubed fans than new,
perhaps even lower rate but it could take a few more years of
service to be certain about that.

In addition to Panaflo the NMB fans are also good at 5V, but are
slightly noisier due to their ball-bearing (but that ball
bearing(s) make them better for high-heat areas like a low flow
PSU exhaust.

How are sleeve bearings made? Sounds like a dodgy setup to me - what's to stop the sleeve wearing?

Powdered bronze impregnated with oil. If they are high-precision
and the blade/hub assmbly is well balanced they will provide a
fine service life providing ambient temp is moderate, and they
are mounted in a horizontal position. Ball bearings are
preferred for non-horizontal due to their preloading (should have
small spring inside bearing cavity or on shaft). The primary
problem with them is when a poor quality fan is used in the
higher ambient temp environment, particularly video cards and
power supply exhausts. Hopefully they'll be quiet loud prior to
failure but once they sieze it's the worst possible situation, a
pleasantly quiet PC due to it not spinning-up at all when turned
on, and parts bake, similar to situation you saw with the
water-cooled PSU... maybe worse but can depend on overall case
pressurization, how much air the other fans force through the
power supply.

Panaflo (Panasonic) has tweaked the sleeve-bearing design a bit
but also they use a larger shaft than many.

http://www.panasonic.com/industrial/...anfeatures.pdf

Hmph, CPC don't sell them. But I see many on ebay!


--
*****TWO BABY CONURES***** 15 parrots and increasing http://www.petersparrots.com
93 silly video clips http://www.insanevideoclips.com
1259 digital photos http://www.petersphotos.com
Served from a pentawatercooled dual silent Athlon 2.8 with terrabyte raid

Make like a post-it note and stick around....

"Peter Hucker" wrote in message news:opsbk78rqpaiowgp@blue...

I checked the heatsink temperatures with my finger.

Did you measure the voltage on the heatsink before you did this,
in case it had 170VDC riding on it?

The heatsink that was bolted the the earthed PSU chassis? No.

A heatsink bolted to the power supply chassis indicates a
Fortron-Source supply. If so, you ruined one of the best power
supplies available.

Haven't you ever noticed how other transformers, including those
inside AC wall adapters, sometimes run very hot?

I found one hot inductor/coil/transformer/whatever it is
(just two wires to it) that was warm, I put a passive
heatsinnk on that and it kept it at less than doby temperature.

That's a choke, and the problem with heatsinking inductors is that
their cores don't conduct heat well or have little surface area for a
heatsink. And toroid chokes have wire wrapped all around them,
meaning you don't want a heatsink mounted against the wiring since it
could be shorted.

I believe a test of one done by www.silentpcreview.com was not
very enthusiastic, probably because the company simply took the
same basic 65-75% efficiency design that's been in PCs since
1980 and tried to make it fanless by merely enlarging the
heatsinks and adding more vent holes. They should have instead
raised the efficiency to around 85-90% because such supplies
are common for non-PC purposes. The best I've seen was 96%,
but it was expensive.

75% to me sounds rediculously low, but then I don't know much
about the design of switched modes. I thought switched modes gave
of a lot less heat than the old ones?

75% is above average for an ATX supply, and linear supplies haven't
been used for PCs since maybe 1980. I suspect switching supplies have
been preferred mostly for their lighter weight, not increased
efficiency, because by operating the transformer at a much higher
frequency, it can be made much smaller for the same amount of power,
and the filter capacitors can also be smaller.

Fans can be made almost silent by balancing them and mounting
them on shock absorbers.
At the very least, have a fan that automatically comes on if the
temperature gets too hot

I have actually got a thermostat here and some large fans to try
this with. If they come on a lot, or are too loud at 5 volts,
then perhaps I'll go and buy some panaflows which Kony claims are
very quiet.

Kony is right about Panaflos, and large fans can be quieter because
they don't have to spin as quickly for the same airflow and will
produce less bearing noise. Also sound reflections inside the
computer case can make fans sound louder, so consider lining the
interior with padding, always taking care to not use anything
flammable. Teflon-coated fiberglass cloth for draperies may be the
best choice, and it doesn't shed fibers nearly as badly as ordinary
fiberglass cloth does.

On Sat, 24 Jul 2004 09:01:17 +0100, "Peter Hucker"
wrote:

snip

I find (my) ideal to be a mix of synthetic motor oil and
synthetic grease, barely thick enough that it's drop-point is
above room temp.

I've got some motor oil, and some grease for the car's driveshaft - a mix of these two? Is the grease on it's own too thick?

Yes, the grease alone is too thick.


Panaflo (Panasonic) has tweaked the sleeve-bearing design a bit
but also they use a larger shaft than many.

http://www.panasonic.com/industrial/...anfeatures.pdf

Hmph, CPC don't sell them. But I see many on ebay!

Don't know what the going rate is for them in the UK but one of
this NG's participants sells them,
http://homepage.ntlworld.com/dorothy...ry/panaflo.htm

On 24 Jul 2004 01:35:38 -0700, do_not_spam_me wrote:

"Peter Hucker" wrote in message news:opsbk78rqpaiowgp@blue...

I checked the heatsink temperatures with my finger.

Did you measure the voltage on the heatsink before you did this,
in case it had 170VDC riding on it?

The heatsink that was bolted the the earthed PSU chassis? No.

A heatsink bolted to the power supply chassis indicates a
Fortron-Source supply. If so, you ruined one of the best power
supplies available.

I got it for a fiver!

Haven't you ever noticed how other transformers, including those
inside AC wall adapters, sometimes run very hot?

I found one hot inductor/coil/transformer/whatever it is
(just two wires to it) that was warm, I put a passive
heatsinnk on that and it kept it at less than doby temperature.

That's a choke, and the problem with heatsinking inductors is that
their cores don't conduct heat well or have little surface area for a
heatsink. And toroid chokes have wire wrapped all around them,
meaning you don't want a heatsink mounted against the wiring since it
could be shorted.

The outside of it was square in shape, and flat. A breeze of air wouldn't have cooled it any better than the heatsink (the entire exposed surface of it was below body temperature with the heatsink on it.

I believe a test of one done by www.silentpcreview.com was not
very enthusiastic, probably because the company simply took the
same basic 65-75% efficiency design that's been in PCs since
1980 and tried to make it fanless by merely enlarging the
heatsinks and adding more vent holes. They should have instead
raised the efficiency to around 85-90% because such supplies
are common for non-PC purposes. The best I've seen was 96%,
but it was expensive.

75% to me sounds rediculously low, but then I don't know much
about the design of switched modes. I thought switched modes gave
of a lot less heat than the old ones?

75% is above average for an ATX supply, and linear supplies haven't
been used for PCs since maybe 1980. I suspect switching supplies have
been preferred mostly for their lighter weight, not increased
efficiency, because by operating the transformer at a much higher
frequency, it can be made much smaller for the same amount of power,
and the filter capacitors can also be smaller.

I assumed better efficiency, as when you get one of hose plug in power supplies (for charging a mobile phone etc), the ones that are heavy (presumably just a transformer and a rectifier) get hot, while the very lightweight ones do not.

Fans can be made almost silent by balancing them and mounting
them on shock absorbers.
At the very least, have a fan that automatically comes on if the
temperature gets too hot

I have actually got a thermostat here and some large fans to try
this with. If they come on a lot, or are too loud at 5 volts,
then perhaps I'll go and buy some panaflows which Kony claims are
very quiet.

Kony is right about Panaflos, and large fans can be quieter because
they don't have to spin as quickly for the same airflow and will
produce less bearing noise. Also sound reflections inside the
computer case can make fans sound louder, so consider lining the
interior with padding, always taking care to not use anything
flammable. Teflon-coated fiberglass cloth for draperies may be the
best choice, and it doesn't shed fibers nearly as badly as ordinary
fiberglass cloth does.

Is padding not going to insulate the case so I would then need more cooling anyway?



--
*****TWO BABY CONURES***** 15 parrots and increasing http://www.petersparrots.com
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Why are there 5 syllables in the word "monosyllabic"?

On Sat, 24 Jul 2004 08:38:58 GMT, kony wrote:

On Sat, 24 Jul 2004 09:01:17 +0100, "Peter Hucker"
wrote:

snip

I find (my) ideal to be a mix of synthetic motor oil and
synthetic grease, barely thick enough that it's drop-point is
above room temp.

I've got some motor oil, and some grease for the car's driveshaft - a mix of these two? Is the grease on it's own too thick?

Yes, the grease alone is too thick.


Panaflo (Panasonic) has tweaked the sleeve-bearing design a bit
but also they use a larger shaft than many.

http://www.panasonic.com/industrial/...anfeatures.pdf

Hmph, CPC don't sell them. But I see many on ebay!

Don't know what the going rate is for them in the UK but one of
this NG's participants sells them,
http://homepage.ntlworld.com/dorothy...ry/panaflo.htm

Thanks! Bookmarked.

--
*****TWO BABY CONURES***** 15 parrots and increasing http://www.petersparrots.com
93 silly video clips http://www.insanevideoclips.com
1259 digital photos http://www.petersphotos.com
Served from a pentawatercooled dual silent Athlon 2.8 with terrabyte raid

Why did the Blonde put ice in her boyfriend's condom?
To keep the swelling down.