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==============================================================================
TOPIC: Yet another bulging-capacitors replacement
http://groups.google.com/group/sci.electronics.repair/t/3ec97de65fce9bb3?hl=en
==============================================================================

== 1 of 9 ==
Date: Fri, Aug 27 2010 12:29 am
From: "N_Cook"

Jeff Liebermann <jeffl@cruzio.com> wrote in message
news:jh3e761hp6mg3b0sb1h6stsdsq19g2mk0m@4ax.com...
> On Fri, 27 Aug 2010 01:27:14 +0100, "Arfa Daily"
> <arfa.daily@ntlworld.com> wrote:
>
> >Anyone
> >else got any constructive comments on the subject of thermal interfacing
of
> >coolers to high power chips ?
>
> In a past life, I used to design HF SSB marine radios. The typical
> transmitter was Class AB 150 watts with about 30% efficiency. That's
> two devices, dissipating about 125 watts each, over an area of about
> 70 sq-cm. Oh yes, no fan allowed.
>
> This is quite a bit more dissipation than the average desktop, causing
> some things to be more critical. In the process of getting it to
> work, I learned a few things.
>
> 1. The less silicon grease used, the better. The idea behind silicon
> grease is to fill in the gaps, scratches, and gouges in the power
> transistor base and aluminum heat sink. Cross sectional
> microphotographs show metal to metal contact on the peaks, but huge
> gaps, filled with silicon grease, in between. Under ideal
> circumstances, maximum metal to metal contact, with minimum gaps is
> the target practice.
>
> 2. All heat sinks and transistor bases are NOT flat. I made a
> dramatic improvement to the measured thermal resistance by polishing
> flat the base of the xsistor and the face of the heat sink. That
> meant removing the gold from the copper base, but that's what was
> necessary. I used a Moire pattern to measure flatness. A mirror
> finish was best, but difficult to achieve. To prevent corrosion, I
> plated the exposed copper with electroless tin or silver. For the
> aluminum heat sink, I just used abrasive polish and a glass polishing
> plate to obtain a mirror finish and flat surface.
>
> 3. Compression pressure is important. None of the standard spring
> clip CPU heat sink holders come even close to optimum. Compression
> adjusts for the bends, and also provides some level of galling to
> provide metal to metal contact. If done correctly, adding silicon
> grease actually increases the thermal resistance. However, this is
> difficult to do with a CPU that has components on the bottom side,
> thus preventing compression. Applying pressure only on the top center
> of the CPU, will cause the substrate to bend, and eventually break. I
> have some ideas, but nothing that can be retrofitted to an existing
> motherboard and CPU socket. This is close, but not optimum:
> <http://www.frostytech.com/articleview.cfm?articleID=2273>
> Note the comments on base finish and flatness.
>
> So, if you want the best head sinking, polish flat the CPU top
> (removing all the laser scribbled markings, polish the heat sink face,
> use very very very very little silicon grease, and compress the
> sandwich until it nearly breaks the CPU.
>
> --
> Jeff Liebermann jeffl@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558

Any opinions on silipads? From my limited trials mica sheet and absolute
minimal white grease has better thermal transfer. Emphasis again on minimal.
Having to decide this week whether to spend out on 6 MJ series TO3 devices
in an old Carver amp failed due to one of the driver TO3 being pushed
through a heap of white grease , so grease on pins getting inside the TO3
socket housing , so insulating partially and eventually burning up the pin .

== 2 of 9 ==
Date: Fri, Aug 27 2010 5:25 am
From: Archon

On 8/26/2010 8:27 PM, Arfa Daily wrote:
>
>
> "Meat Plow" <mhywatt@yahoo.com> wrote in message
> news:pan.2010.08.26.21.04.20@hahahahahahahah.nutz.I.am...
>> On Thu, 26 Aug 2010 13:20:18 -0700, whit3rd wrote:
>>
>>> I recently had a rash of reboot events on my trusty old iMac G5 (1.8
>>> GHz).
>>> This has already had the logic board replaced, as these machines had
>>> some bad-filter-capacitor issues... but this time it was the capacitors
>>> in the power supply, not on the logic board, that were bulging and
>>> leaking electrolyte.
>>>
>>> It took an hour or two of catalog work to find low-ESR replacements for
>>> the
>>> nine low-V high-I filter capacitors in the power supply, in form factors
>>> that would fit the cramped footprint of the originals. So, I thought
>>> I'd relate the parts list here, in case anyone else has need of such
>>> info.
>>>
>>> C40 and C52 10V 1000 uF
>>> EKY-100ELL102MH20D
>>>
>>> C45, C55 and C56 2200 uF 10V
>>> UHM1A222MPD
>>>
>>> C47 16V 1200 uF
>>> UHE1C122MPD
>>>
>>> C49 10V 3300 uF
>>> UHN1A332MHD ** this is slightly larger diameter than the
>>> original, but it fits **
>>> UHZ0J332MPM **right size, but less voltage margin**
>>>
>>> C59 35V 330 uF
>>> ELXV350ELL331MJ20S
>>>
>>> C64 15V 1000 uF
>>> EEU-FC1E102B
>>>
>>> These were all in stock at Mouser Electronics, if that matters.
>>
>> Hell yes it matters. I'm going to fix a year old Coolmax 650 watt PC PSU
>> and will be looking for some replacement caps. I like to keep a spare and
>> I need 650 with this new AMD 120 watt quad core PhenomII 3.2 ghz CPU and
>> Asus M4A78E-T mobo. With Asus overclocking friendly special settings I'm
>> able to run it at 4.0 ghz for each core. Makes video encoding on an
>> application supporting multicore encoding really fly. Not unusual to get
>> over 350 frames/sec out of NTSC 740x480 avi's. I can make a high quality
>> 20 chapter DVD with all the bells and whistles in about an hour. Used to
>> take 24 hours on a 2ghz single core AMD :)
>>
>>
>>
>
> Just as a matter of interest Meat, what is your preferred brand and type
> of heatsink goop when working with these very high power processors?
> I've recently been working with some games machines that have two very
> powerful processors on the board, and have been having some thermal
> issues when using 'standard' white silicon grease on them, which appears
> to be what the manufacturer used originally. I have today reassembled
> one using some Arctic Silver compound instead, and it seems to be doing
> a fine job. I have always resisted using this stuff, because it's so
> messy, and so hard to remove unless you use the complementary cleaner,
> but if it really is that much more effective, then I might be prepared
> to live with these shortcomings. Anyone else got any constructive
> comments on the subject of thermal interfacing of coolers to high power
> chips ?
>
> Arfa
On games PC's i've gone to water cooling, blissfully quiet (apart from
the fishtank type noise!), CPU and GPU a few degrees above room temp
even at full load. Never go back to jet engine graphics card fans.
JC

== 3 of 9 ==
Date: Fri, Aug 27 2010 6:09 am
From: Meat Plow

On Fri, 27 Aug 2010 01:27:14 +0100, Arfa Daily wrote:

> "Meat Plow" <mhywatt@yahoo.com> wrote in message
> news:pan.2010.08.26.21.04.20@hahahahahahahah.nutz.I.am...
>> On Thu, 26 Aug 2010 13:20:18 -0700, whit3rd wrote:
>>
>>> I recently had a rash of reboot events on my trusty old iMac G5 (1.8
>>> GHz).
>>> This has already had the logic board replaced, as these machines had
>>> some bad-filter-capacitor issues... but this time it was the
>>> capacitors in the power supply, not on the logic board, that were
>>> bulging and leaking electrolyte.
>>>
>>> It took an hour or two of catalog work to find low-ESR replacements
>>> for the
>>> nine low-V high-I filter capacitors in the power supply, in form
>>> factors that would fit the cramped footprint of the originals. So, I
>>> thought I'd relate the parts list here, in case anyone else has need
>>> of such info.
>>>
>>> C40 and C52 10V 1000 uF
>>> EKY-100ELL102MH20D
>>>
>>> C45, C55 and C56 2200 uF 10V
>>> UHM1A222MPD
>>>
>>> C47 16V 1200 uF
>>> UHE1C122MPD
>>>
>>> C49 10V 3300 uF
>>> UHN1A332MHD ** this is slightly larger diameter than the
>>> original, but it fits **
>>> UHZ0J332MPM **right size, but less voltage margin**
>>>
>>> C59 35V 330 uF
>>> ELXV350ELL331MJ20S
>>>
>>> C64 15V 1000 uF
>>> EEU-FC1E102B
>>>
>>> These were all in stock at Mouser Electronics, if that matters.
>>
>> Hell yes it matters. I'm going to fix a year old Coolmax 650 watt PC
>> PSU and will be looking for some replacement caps. I like to keep a
>> spare and I need 650 with this new AMD 120 watt quad core PhenomII 3.2
>> ghz CPU and Asus M4A78E-T mobo. With Asus overclocking friendly special
>> settings I'm able to run it at 4.0 ghz for each core. Makes video
>> encoding on an application supporting multicore encoding really fly.
>> Not unusual to get over 350 frames/sec out of NTSC 740x480 avi's. I can
>> make a high quality 20 chapter DVD with all the bells and whistles in
>> about an hour. Used to take 24 hours on a 2ghz single core AMD :)
>>
>>
>>
>>
> Just as a matter of interest Meat, what is your preferred brand and type
> of heatsink goop when working with these very high power processors?
> I've recently been working with some games machines that have two very
> powerful processors on the board, and have been having some thermal
> issues when using 'standard' white silicon grease on them, which appears
> to be what the manufacturer used originally. I have today reassembled
> one using some Arctic Silver compound instead, and it seems to be doing
> a fine job. I have always resisted using this stuff, because it's so
> messy, and so hard to remove unless you use the complementary cleaner,
> but if it really is that much more effective, then I might be prepared
> to live with these shortcomings. Anyone else got any constructive
> comments on the subject of thermal interfacing of coolers to high power
> chips ?
>

You answered your own question. The AMD heatsink / quad core PhenomII 955
Black Edition package comes with Artic Silver already applied. I'm using
an Antec server case that has a hole and tube in the side cover. The end
of the tube fits directly over the CPU heat sink so it draws air directly
from the outside. In back is a pair of 120mm fans controlled by the
mainboard. If the CPU temp goes up all three fans increase according to
the temp. Or you can set them to run at full speed all the time. The 650
watt PSU also has a temp sensing 120mm fan. So the box is really quiet
most of the time. But when rendering video and the CPU usage hovers
around 50% fan speed increases slightly. Video rendering with an
application that takes advantage of multi-core processors seem to use the
most CPU percentage. I've never seen it go over 50%. Most of the time it
doesn't go over 10%.

--
Live Fast, Die Young and Leave a Pretty Corpse

== 4 of 9 ==
Date: Fri, Aug 27 2010 6:12 am
From: Meat Plow

On Fri, 27 Aug 2010 08:29:01 +0100, N_Cook wrote:

> Any opinions on silipads? From my limited trials mica sheet and absolute
> minimal white grease has better thermal transfer. Emphasis again on
> minimal. Having to decide this week whether to spend out on 6 MJ series
> TO3 devices in an old Carver amp failed due to one of the driver TO3
> being pushed through a heap of white grease , so grease on pins getting
> inside the TO3 socket housing , so insulating partially and eventually
> burning up the pin .

I've seen pads used in a lot of high power amps. Soundcraftsmen, BGW,
Carver, Peavey, Crown all used them at some time or another. If the
devices are torqued down properly I don't have a problem with them. You
are talking about the rubberized pads with embedded compound right?

--
Live Fast, Die Young and Leave a Pretty Corpse

== 5 of 9 ==
Date: Fri, Aug 27 2010 8:38 am
From: Jeff Liebermann

On Fri, 27 Aug 2010 08:29:01 +0100, "N_Cook" <diverse@tcp.co.uk>
wrote:

>Any opinions on silipads? From my limited trials mica sheet and absolute
>minimal white grease has better thermal transfer. Emphasis again on minimal.

Do the math. Silicon impregnated rubber TO-3 pads have a thermal
resistance of about 0.4K/watt. 0.0002" Mica, with silicon grease
smeared on both sides is about 0.6K/watt. Depending on your total
power dissipation, that's hardly any difference. However, if your
heat sink is undersized, buried inside a cabinet, or located in a
place where there's no air flow, it might make a difference.

<http://www.wakefield.com/LinkClick.aspx?fileticket=1ULQQwz8xmU%3d&tabid=64>
See Page 6-8. The example shown is for a TO-3 packaged device.

>Having to decide this week whether to spend out on 6 MJ series TO3 devices
>in an old Carver amp failed due to one of the driver TO3 being pushed
>through a heap of white grease , so grease on pins getting inside the TO3
>socket housing , so insulating partially and eventually burning up the pin .

Keep it stock. However, if this is a push-pull type of amp, where the
thermal balance of the xsistors has an effect on the bias point,
crossover distortion, and possibly linearity, I would make sure that
whatever you do to one side, the same gets done to the other.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 6 of 9 ==
Date: Fri, Aug 27 2010 6:04 pm
From: "Arfa Daily"

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:jh3e761hp6mg3b0sb1h6stsdsq19g2mk0m@4ax.com...
> On Fri, 27 Aug 2010 01:27:14 +0100, "Arfa Daily"
> <arfa.daily@ntlworld.com> wrote:
>
>>Anyone
>>else got any constructive comments on the subject of thermal interfacing
>>of
>>coolers to high power chips ?
>
> In a past life, I used to design HF SSB marine radios. The typical
> transmitter was Class AB 150 watts with about 30% efficiency. That's
> two devices, dissipating about 125 watts each, over an area of about
> 70 sq-cm. Oh yes, no fan allowed.
>
> This is quite a bit more dissipation than the average desktop, causing
> some things to be more critical. In the process of getting it to
> work, I learned a few things.
>
> 1. The less silicon grease used, the better. The idea behind silicon
> grease is to fill in the gaps, scratches, and gouges in the power
> transistor base and aluminum heat sink. Cross sectional
> microphotographs show metal to metal contact on the peaks, but huge
> gaps, filled with silicon grease, in between. Under ideal
> circumstances, maximum metal to metal contact, with minimum gaps is
> the target practice.
>
> 2. All heat sinks and transistor bases are NOT flat. I made a
> dramatic improvement to the measured thermal resistance by polishing
> flat the base of the xsistor and the face of the heat sink. That
> meant removing the gold from the copper base, but that's what was
> necessary. I used a Moire pattern to measure flatness. A mirror
> finish was best, but difficult to achieve. To prevent corrosion, I
> plated the exposed copper with electroless tin or silver. For the
> aluminum heat sink, I just used abrasive polish and a glass polishing
> plate to obtain a mirror finish and flat surface.
>
> 3. Compression pressure is important. None of the standard spring
> clip CPU heat sink holders come even close to optimum. Compression
> adjusts for the bends, and also provides some level of galling to
> provide metal to metal contact. If done correctly, adding silicon
> grease actually increases the thermal resistance. However, this is
> difficult to do with a CPU that has components on the bottom side,
> thus preventing compression. Applying pressure only on the top center
> of the CPU, will cause the substrate to bend, and eventually break. I
> have some ideas, but nothing that can be retrofitted to an existing
> motherboard and CPU socket. This is close, but not optimum:
> <http://www.frostytech.com/articleview.cfm?articleID=2273>
> Note the comments on base finish and flatness.
>
> So, if you want the best head sinking, polish flat the CPU top
> (removing all the laser scribbled markings, polish the heat sink face,
> use very very very very little silicon grease, and compress the
> sandwich until it nearly breaks the CPU.
>
> --
> Jeff Liebermann jeffl@cruzio.com

Thanks for the insights Jeff. All interesting stuff. These are dedicated
games machines, not based on a PC in any way. The power supply is specced to
deliver 12v at 23 amps, yes, that's twenty three amps ...

Almost all of this is potentially going into these two processors, so not
far off 300 watts between them. No mean task shifting the heat off them !

Arfa

== 7 of 9 ==
Date: Fri, Aug 27 2010 6:08 pm
From: "Arfa Daily"

"Meat Plow" <mhywatt@yahoo.com> wrote in message
news:pan.2010.08.27.13.09.02@hahahahahahahah.nutz.I.am...
> On Fri, 27 Aug 2010 01:27:14 +0100, Arfa Daily wrote:
>
>> "Meat Plow" <mhywatt@yahoo.com> wrote in message
>> news:pan.2010.08.26.21.04.20@hahahahahahahah.nutz.I.am...
>>> On Thu, 26 Aug 2010 13:20:18 -0700, whit3rd wrote:
>>>
>>>> I recently had a rash of reboot events on my trusty old iMac G5 (1.8
>>>> GHz).
>>>> This has already had the logic board replaced, as these machines had
>>>> some bad-filter-capacitor issues... but this time it was the
>>>> capacitors in the power supply, not on the logic board, that were
>>>> bulging and leaking electrolyte.
>>>>
>>>> It took an hour or two of catalog work to find low-ESR replacements
>>>> for the
>>>> nine low-V high-I filter capacitors in the power supply, in form
>>>> factors that would fit the cramped footprint of the originals. So, I
>>>> thought I'd relate the parts list here, in case anyone else has need
>>>> of such info.
>>>>
>>>> C40 and C52 10V 1000 uF
>>>> EKY-100ELL102MH20D
>>>>
>>>> C45, C55 and C56 2200 uF 10V
>>>> UHM1A222MPD
>>>>
>>>> C47 16V 1200 uF
>>>> UHE1C122MPD
>>>>
>>>> C49 10V 3300 uF
>>>> UHN1A332MHD ** this is slightly larger diameter than the
>>>> original, but it fits **
>>>> UHZ0J332MPM **right size, but less voltage margin**
>>>>
>>>> C59 35V 330 uF
>>>> ELXV350ELL331MJ20S
>>>>
>>>> C64 15V 1000 uF
>>>> EEU-FC1E102B
>>>>
>>>> These were all in stock at Mouser Electronics, if that matters.
>>>
>>> Hell yes it matters. I'm going to fix a year old Coolmax 650 watt PC
>>> PSU and will be looking for some replacement caps. I like to keep a
>>> spare and I need 650 with this new AMD 120 watt quad core PhenomII 3.2
>>> ghz CPU and Asus M4A78E-T mobo. With Asus overclocking friendly special
>>> settings I'm able to run it at 4.0 ghz for each core. Makes video
>>> encoding on an application supporting multicore encoding really fly.
>>> Not unusual to get over 350 frames/sec out of NTSC 740x480 avi's. I can
>>> make a high quality 20 chapter DVD with all the bells and whistles in
>>> about an hour. Used to take 24 hours on a 2ghz single core AMD :)
>>>
>>>
>>>
>>>
>> Just as a matter of interest Meat, what is your preferred brand and type
>> of heatsink goop when working with these very high power processors?
>> I've recently been working with some games machines that have two very
>> powerful processors on the board, and have been having some thermal
>> issues when using 'standard' white silicon grease on them, which appears
>> to be what the manufacturer used originally. I have today reassembled
>> one using some Arctic Silver compound instead, and it seems to be doing
>> a fine job. I have always resisted using this stuff, because it's so
>> messy, and so hard to remove unless you use the complementary cleaner,
>> but if it really is that much more effective, then I might be prepared
>> to live with these shortcomings. Anyone else got any constructive
>> comments on the subject of thermal interfacing of coolers to high power
>> chips ?
>>
>
> You answered your own question. The AMD heatsink / quad core PhenomII 955
> Black Edition package comes with Artic Silver already applied. I'm using
> an Antec server case that has a hole and tube in the side cover. The end
> of the tube fits directly over the CPU heat sink so it draws air directly
> from the outside. In back is a pair of 120mm fans controlled by the
> mainboard. If the CPU temp goes up all three fans increase according to
> the temp. Or you can set them to run at full speed all the time. The 650
> watt PSU also has a temp sensing 120mm fan. So the box is really quiet
> most of the time. But when rendering video and the CPU usage hovers
> around 50% fan speed increases slightly. Video rendering with an
> application that takes advantage of multi-core processors seem to use the
> most CPU percentage. I've never seen it go over 50%. Most of the time it
> doesn't go over 10%.
>

Yes, seems to be 'busy' video rendering that causes all the problems on the
machines I am working on. Q & D calcs show that at max chat, the two
processors are potentially using close to 300 watts of input power between
them, and the heat that this generates in them, takes some shifting ...

Arfa

== 8 of 9 ==
Date: Fri, Aug 27 2010 7:18 pm
From: Jim Yanik

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in
news:dgZdo.79946$Pa3.38201@hurricane:

>
>
> "Jeff Liebermann" <jeffl@cruzio.com> wrote in message
> news:jh3e761hp6mg3b0sb1h6stsdsq19g2mk0m@4ax.com...
>> On Fri, 27 Aug 2010 01:27:14 +0100, "Arfa Daily"
>> <arfa.daily@ntlworld.com> wrote:
>>
>>>Anyone
>>>else got any constructive comments on the subject of thermal
>>>interfacing of
>>>coolers to high power chips ?
>>
>> In a past life, I used to design HF SSB marine radios. The typical
>> transmitter was Class AB 150 watts with about 30% efficiency. That's
>> two devices, dissipating about 125 watts each, over an area of about
>> 70 sq-cm. Oh yes, no fan allowed.
>>
>> This is quite a bit more dissipation than the average desktop,
>> causing some things to be more critical. In the process of getting
>> it to work, I learned a few things.
>>
>> 1. The less silicon grease used, the better. The idea behind
>> silicon grease is to fill in the gaps, scratches, and gouges in the
>> power transistor base and aluminum heat sink. Cross sectional
>> microphotographs show metal to metal contact on the peaks, but huge
>> gaps, filled with silicon grease, in between. Under ideal
>> circumstances, maximum metal to metal contact, with minimum gaps is
>> the target practice.
>>
>> 2. All heat sinks and transistor bases are NOT flat. I made a
>> dramatic improvement to the measured thermal resistance by polishing
>> flat the base of the xsistor and the face of the heat sink. That
>> meant removing the gold from the copper base, but that's what was
>> necessary. I used a Moire pattern to measure flatness. A mirror
>> finish was best, but difficult to achieve. To prevent corrosion, I
>> plated the exposed copper with electroless tin or silver. For the
>> aluminum heat sink, I just used abrasive polish and a glass polishing
>> plate to obtain a mirror finish and flat surface.
>>
>> 3. Compression pressure is important. None of the standard spring
>> clip CPU heat sink holders come even close to optimum. Compression
>> adjusts for the bends, and also provides some level of galling to
>> provide metal to metal contact. If done correctly, adding silicon
>> grease actually increases the thermal resistance. However, this is
>> difficult to do with a CPU that has components on the bottom side,
>> thus preventing compression. Applying pressure only on the top
>> center of the CPU, will cause the substrate to bend, and eventually
>> break. I have some ideas, but nothing that can be retrofitted to an
>> existing motherboard and CPU socket. This is close, but not optimum:
>> <http://www.frostytech.com/articleview.cfm?articleID=2273>
>> Note the comments on base finish and flatness.
>>
>> So, if you want the best head sinking, polish flat the CPU top
>> (removing all the laser scribbled markings, polish the heat sink
>> face, use very very very very little silicon grease, and compress the
>> sandwich until it nearly breaks the CPU.
>>
>> --
>> Jeff Liebermann jeffl@cruzio.com
>
>
> Thanks for the insights Jeff. All interesting stuff. These are
> dedicated games machines, not based on a PC in any way. The power
> supply is specced to deliver 12v at 23 amps, yes, that's twenty three
> amps ...
>
> Almost all of this is potentially going into these two processors, so
> not far off 300 watts between them. No mean task shifting the heat off
> them !
>
> Arfa
>
>

what processors(microprocessors?) run at 12V?
ISTR that today's uPs run mostly on 3.3V

Most other digital logic runs at 5V,I believe.

I think you wil find that most of your power is going into the video drive
(or LCD backlight) circuitry.

--
Jim Yanik
jyanik
at
localnet
dot com

== 9 of 9 ==
Date: Fri, Aug 27 2010 8:19 pm
From: Jeff Liebermann

On Sat, 28 Aug 2010 02:04:07 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

>Thanks for the insights Jeff.

There was quite a bit of "Learn By Destroying(tm)" involved. Measuring
flatness and thermal resistance were a major exercise, but settled all
kinds of lab arguments.

Incidentally, you might be interested in how Arctic Silver works.
<http://www.arcticsilver.com/products.htm>
<http://www.arcticsilver.com/msds.htm>
Silver has a much higher thermal conductivity (410 W/m*K) as compared
to zinc oxide (21 W/m*K) and aluminum oxide (30 W/m*K) which is what's
in common thermal compound.
<http://en.wikipedia.org/wiki/List_of_thermal_conductivities>
However, if your shove an ohms-guesser into a puddle of Arctic Silver,
it's not conductive. That's because the particles of silver are so
far and few, that the bulk of the solution is polyolester or mineral
oil, which insulates the particles from each other, preventing mutual
contact. However, if you tear apart a CPU/heatsink that's been used
for a while, you'll notice that the Arctic Silver is a thick and dense
paste which is conductive. What has happened is that the polyol ester
mixture has evaporated sufficiently to provide contact between
particles. Since thermal conductivity is best through the silver
particles, the result is a superior thermal connection, with the
sliver particles filling the voids. You could do the same thing with
silver dust, but it would difficult to handle and apply. Meanwhile,
ordinary silicon grease does the same thing, but there's a difference.
The oil does not evaporate as easily, and the ceramic particles are
much larger and less compressible than the silver particles. Fewer
points of contact and lower thermal conductivity of ceramic, means a
worse thermal connection.

>All interesting stuff. These are dedicated
>games machines, not based on a PC in any way. The power supply is specced to
>deliver 12v at 23 amps, yes, that's twenty three amps ...
>
>Almost all of this is potentially going into these two processors, so not
>far off 300 watts between them. No mean task shifting the heat off them !

I don't believe it. The winner of the power hogging consumer CPU
contest was the DEC/Intel Alpha 21364 (EV79):
<http://en.wikipedia.org/wiki/Alpha_21364>
which burned 155 watts. Itanium II came close with 130 watts (per
core). I had an Alpha CPU machine to play with for a while, which
would burn my hand from the hot air coming out the back.

If you have a power line wattmeter or a Kill-A-Watt meter, I think a
measurement would be helpful.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

==============================================================================
TOPIC: Simplest way to Unlock iPhone
http://groups.google.com/group/sci.electronics.repair/t/7a182ed63149f989?hl=en
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== 1 of 1 ==
Date: Fri, Aug 27 2010 2:14 am
From: jenneylist

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TOPIC: HOT BABES
http://groups.google.com/group/sci.electronics.repair/t/b5af0b3a11dfe276?hl=en
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From: guru

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TOPIC: vestel 11AK36 A8 TV - PSU not starting
http://groups.google.com/group/sci.electronics.repair/t/40010e9e2ff31ad0?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Aug 27 2010 5:05 am
From: b

This 14" 11AK36-A8 tv apparently 'just went off.' there was evidence
of a short near the mains inlet, on the print side of the pcb -
probably a strand of wire or blob of solder from the time of
manufcture had been the cause. checked rectifier, removed PTC in case,
replaced fuse. Set dead. 0v at psu o/ps.

checked the obvious in psu primary, no shorted diodes or open
resistors. Removed secondary diodes including HT line.

schematics here (5m). Psu is on page 24.: http://www.fileden.com/files/2007/6/4/1143893//11AK36
FULL.pdf

...not identical but the main aspects are the same.

300v present across mains capacitor, and at R821 (safety) and
collector of Q801.
25v present at c811, suggesting the uPc of the PSU has power.

I don't know where to look now. My next step would be to change the
uPc UC3843, but I don't think I've ever seen a case where the chip
went on its own...

I should probably have tossed this aside by now but I'm just keen to
satisfy my curiosity. So I'm all ears.
cheers,
B.

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http://groups.google.com/group/sci.electronics.repair/t/674febdf8c46c762?hl=en
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== 1 of 1 ==
Date: Fri, Aug 27 2010 7:34 am
From: "N_Cook"

not vibrations but good verbrations , whatever that is
What an overpriced heap of junk. On pulling off this rubbery plastic film
one of the SM caps came off with it. The film is not stuck to the components
with any force, a needle under it and it lifts quite easily off pcb etc
except where its lodged between IC pins. The SM C&R near the main chip that
I had wire brushed were firm enough. Poor PbF solder under pin 22 was the
main problem but what else lurks under the rest of the black stuff I've not
touched?
Standard die cast box with no bumpons under to stop it sliding, no separate
battery housing so you have to fully open up to replace battery . The power
socket loose and no 1/2 inch 25 TPI bush nut available this side of the
pond, to rob off something, to replace it, maker had hand filed out hole in
the box to receive the socket (because of flats). Looks as though I'll have
to continue the spirit of bodge, with hotmelt glue inside to keep this
socket in place.

==============================================================================
TOPIC: Semi-conductor-Answer
http://groups.google.com/group/sci.electronics.repair/t/bc3822e35eab24b0?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Aug 27 2010 8:13 am
From: Bob Villa

On Aug 24, 1:47 pm, Bob Villa <pheeh.z...@gmail.com> wrote:
> On Aug 24, 9:40 am, "ian field" <gangprobing.al...@ntlworld.com>
> wrote:
>
> >http://www.murata.com/products/catalog/pdf/k99/k99e_l0725.pdf
>
> I went to an electrician and this is what I got...
>
> http://stearns.rexnord.com/products/Cat_902_table.asp
>
> Thanks for the help guys!

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TOPIC: Digimate L-1715 inverter part ID needed
http://groups.google.com/group/sci.electronics.repair/t/e7777d19925a9def?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Aug 27 2010 7:00 pm
From: who where

On Fri, 27 Aug 2010 07:56:07 +0100, Clyde
<mkdrummeyNOSPAMPLEASE@hotmail.com> wrote:

>Hi. Just got a Digimate 17 inch monitor with no display. Found a bad
>shottky diode on the inverter PCB so I replaced that and the fuse, now I
>have a screen, however after a few minutes it starts to flicker badly,
>on the inverter the transformer on the side I replaced the diode is
>getting hot. After a bit of tracing I have found a small SMD (8 pin,
>looks like an IC) which is shorted to all pins. I am unable to read the
>tiny writing on top and can find no information on what the part is.
>Does anyone have any idea, or possibly a schematic. Judging by the way
>it is connected (there is an identical one on the other side of the
>inverter, dual lamp) I think it may actually be a special kind of zener
>diode.
>
>Anyway some numbers, the monitor is a Digimate L-1715 ( I believe the
>inverter is used in a variety of other brands ). The inverter PCB is
>part number IV185030HX. The part I need is identified as Q3 (maybe a
>transistor?)

Best idea is to post this on www.badcaps.net as there are quite a
number of very experienced LCD monitor repair types lurking there.
And read the "how to post pics" advice first, to stay on the right
side of them ;-)

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