What cap mfr. to use?

Spehro Pefhany wrote:

Sylvia Else <sylvia@not.at.this.address> wrote:
Mike Tomlinson wrote:
Dave Platt <dplatt@radagast.org> writes

One manufacturer was citing a "50,000
hour" lifetime figure on the motherboard carton

Are you sure there isn't a microdot in the small print with the words
"electrolytic capacitors excepted" printed on it?


"lifetime" is a word of dubious interpretation. Does it mean that it
won't break in that time, that it can be repaired in that time if it
does break, or something else?

If they claimed an MTBF of 50,000 hours, that would be different.


AFAIUI, MTBF typically applies only to the flat part at the bottom of
teh bathtub curve. They conveniently hack off the infantile failures
at the left and the increasing failures as the useful life expires on
the right. IOW, a product can have a much higher MTFB than the time it
takes to wear out.

Also, 50,000 hours 24/7 is only 5.7 years, which is more-or-less what
you'd expect out of a motherboard.
Click to expand...
And if you run a 105C cap at 40C you'll get ~ 85 times the datasheet
lifetime. So a 2,000 hr 105C cap would last over 19 years. Watch the ripple
current of course !

Interesting point there. One decoupling cap on a mobo of mine near the
graphics card slot was visibly bulged whereas others weren't. I imagine it
was hot air being blown onto it by the GPU fan.

Graham
 
In article <1eb805d7o54jvfhs5keu6ujdsbfiq6gro1@4ax.com>, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> writes

Also, 50,000 hours 24/7 is only 5.7 years, which is more-or-less what
you'd expect out of a motherboard.
Click to expand...
Not from electrolytic caps, which was kind of the point. Even Panasonic
specify only 10k hours for their top of the range electros.

--
(\__/)
(='.'=) Bunny says Windows 7 is Vi$ta reloaded.
(")_(") http://imgs.xkcd.com/comics/windows_7.png
 
On Fri, 8 May 2009 15:08:31 +0100, Mike Tomlinson <mike@jasper.org.uk>
wrote:

In article <1eb805d7o54jvfhs5keu6ujdsbfiq6gro1@4ax.com>, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> writes

Also, 50,000 hours 24/7 is only 5.7 years, which is more-or-less what
you'd expect out of a motherboard.

Not from electrolytic caps, which was kind of the point. Even Panasonic
specify only 10k hours for their top of the range electros.
Click to expand...
I guess that would be a rather serious problem if the temperature
inside your computer case averaged 105°C = 221°F.

http://www.loc.gov/rr/scitech/mysteries/friedegg.html
 
In article <a1g805t0jur8bk1op2tquo3gst152q8ckk@4ax.com>, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> writes

I guess that would be a rather serious problem if the temperature
inside your computer case averaged 105°C = 221°F.
Click to expand...
Seen a modern mainboard recently? Voltage regulation MOSFETs with
heatsinks on, some with their own extractor fans? Heat coupled to the
capacitors by a few millimetres of thick copper PCB trace for excellent
heat conduction?

--
(\__/)
(='.'=) Bunny says Windows 7 is Vi$ta reloaded.
(")_(") http://imgs.xkcd.com/comics/windows_7.png
 
Also, 50,000 hours 24/7 is only 5.7 years, which is more-or-less what
you'd expect out of a motherboard.

Not from electrolytic caps, which was kind of the point. Even Panasonic
specify only 10k hours for their top of the range electros.
Click to expand...
But isn't that at "high" temperatures, or some other extreme operating
condition?
 
On Fri, 8 May 2009 15:37:26 +0100, Mike Tomlinson <mike@jasper.org.uk>
wrote:

In article <a1g805t0jur8bk1op2tquo3gst152q8ckk@4ax.com>, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> writes

I guess that would be a rather serious problem if the temperature
inside your computer case averaged 105°C = 221°F.

Seen a modern mainboard recently?
Click to expand...
Certainly.

Voltage regulation MOSFETs with
heatsinks on, some with their own extractor fans? Heat coupled to the
capacitors by a few millimetres of thick copper PCB trace for excellent
heat conduction?
Click to expand...
Have you put a thermocouple on the capacitors?
 
Mike Tomlinson wrote:

Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> writes

Also, 50,000 hours 24/7 is only 5.7 years, which is more-or-less what
you'd expect out of a motherboard.

Not from electrolytic caps, which was kind of the point. Even Panasonic
specify only 10k hours for their top of the range electros.
Click to expand...
AT RATED TEMP and RATED RIPPLE CURRENT. Rarely found in combination except
by bad design, and it does happen sometimes.

You can get far better by de-rating. Rule of thumb is to reduce the temp
from rated value by 10C and double the lifetime etc etc.

Graham
 
William Sommerwerck wrote:

Also, 50,000 hours 24/7 is only 5.7 years, which is more-or-less what
you'd expect out of a motherboard.

Not from electrolytic caps, which was kind of the point. Even Panasonic
specify only 10k hours for their top of the range electros.

But isn't that at "high" temperatures, or some other extreme operating
condition?
Click to expand...
Yes.

Grham
 
Mike Tomlinson wrote:

Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> writes

I guess that would be a rather serious problem if the temperature
inside your computer case averaged 105°C = 221°F.

Seen a modern mainboard recently? Voltage regulation MOSFETs with
heatsinks on, some with their own extractor fans? Heat coupled to the
capacitors by a few millimetres of thick copper PCB trace for excellent
heat conduction?
Click to expand...
Point 1: You can ventilate your case and CPU far better than 'normal'
methods.

Point 2: leave the side panels off like I tend to do !

Graham
 
Spehro Pefhany wrote:

Mike Tomlinson <mike@jasper.org.uk> wrote:
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> writes

I guess that would be a rather serious problem if the temperature
inside your computer case averaged 105°C = 221°F.

Seen a modern mainboard recently?

Certainly.

Voltage regulation MOSFETs with
heatsinks on, some with their own extractor fans? Heat coupled to the
capacitors by a few millimetres of thick copper PCB trace for excellent
heat conduction?

Have you put a thermocouple on the capacitors?
Click to expand...
You need a themocouple and a suitable meter for that ! ;~)

Graham
 
Sylvia Else wrote:
Mike Tomlinson wrote:
In article <jdkbd6-ue7.ln1@radagast.org>, Dave Platt
dplatt@radagast.org> writes

One manufacturer was citing a "50,000
hour" lifetime figure on the motherboard carton

Are you sure there isn't a microdot in the small print with the words
"electrolytic capacitors excepted" printed on it?


"lifetime" is a word of dubious interpretation. Does it mean that it
won't break in that time, that it can be repaired in that time if it
does break, or something else?

If they claimed an MTBF of 50,000 hours, that would be different.
Click to expand...
Shit, I'd generally be happy with 2000 hours MTBF.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
 
Point 2: Leave the side panels off like I tend to do!
Click to expand...
I do, but that's mostly to make it easy to perform full backups. The machine
run coolers, though it spews more RF, which keeps atomic clocks in the same
room from synching.

By the way, check the CPU cooler occasionally. Mine hadn't been cleaned
since I bought the computer over eight years ago, and you cannot believe how
clogged with shmutz the heat sink was.
 
William Sommerwerck wrote:

Point 2: Leave the side panels off like I tend to do!

I do, but that's mostly to make it easy to perform full backups. The machine
run coolers, though it spews more RF, which keeps atomic clocks in the same
room from synching.
Click to expand...
Not a problem for me.


By the way, check the CPU cooler occasionally. Mine hadn't been cleaned
since I bought the computer over eight years ago, and you cannot believe how
clogged with shmutz the heat sink was.
Click to expand...
I clean them moderately regularly. Plus I don't operate in a very dusty
environment.

Gragam
 
By the way, check the CPU cooler occasionally. Mine
hadn't been cleaned since I bought the computer over
eight years ago, and you cannot believe how clogged
with shmutz the heat sink was.

I clean them moderately regularly. Plus I don't operate
in a very dusty environment.
Click to expand...
Nor do I. This wasn't dust -- it was more like gobs of sub-microscopic
carbon particles.
 
William Sommerwerck wrote:

By the way, check the CPU cooler occasionally. Mine
hadn't been cleaned since I bought the computer over
eight years ago, and you cannot believe how clogged
with shmutz the heat sink was.

I clean them moderately regularly. Plus I don't operate
in a very dusty environment.

Nor do I. This wasn't dust -- it was more like gobs of sub-microscopic
carbon particles.
Click to expand...
Never seen that. On the CPU cooler itself you mean ?

Grham
 
Eeyore wrote:

Mike Tomlinson wrote:

In article <jdkbd6-ue7.ln1@radagast.org>, Dave Platt
dplatt@radagast.org> writes

One manufacturer was citing a "50,000
hour" lifetime figure on the motherboard carton

Are you sure there isn't a microdot in the small print with the words
"electrolytic capacitors excepted" printed on it?

After the bad caps debacle one manufacturer, it might be Gigabyte,
moved to the OSCON type in which case it may very well be true.

Graham
Click to expand...
Yes ! Gigabyte got bitten hard by that and the fake motherboard scam.

--
Best Regards:
Baron.
 
On Fri, 08 May 2009 17:12:11 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

Spehro Pefhany wrote:

Mike Tomlinson <mike@jasper.org.uk> wrote:
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> writes

I guess that would be a rather serious problem if the temperature
inside your computer case averaged 105°C = 221°F.

Seen a modern mainboard recently?

Certainly.

Voltage regulation MOSFETs with
heatsinks on, some with their own extractor fans? Heat coupled to the
capacitors by a few millimetres of thick copper PCB trace for excellent
heat conduction?

Have you put a thermocouple on the capacitors?

You need a themocouple and a suitable meter for that ! ;~)

Graham
Click to expand...
Really? ;-)

Of course many, if not most, portable multimeters have type K
thermocouple inputs (of dubious accuracy, but good enough for this
sort of thing) and many are supplied with a bead thermocouple.
 
On Sat, 09 May 2009 02:16:42 +1000, Bob Larter
<bobbylarter@gmail.com> wrote:

Sylvia Else wrote:
Mike Tomlinson wrote:
In article <jdkbd6-ue7.ln1@radagast.org>, Dave Platt
dplatt@radagast.org> writes

One manufacturer was citing a "50,000
hour" lifetime figure on the motherboard carton

Are you sure there isn't a microdot in the small print with the words
"electrolytic capacitors excepted" printed on it?


"lifetime" is a word of dubious interpretation. Does it mean that it
won't break in that time, that it can be repaired in that time if it
does break, or something else?

If they claimed an MTBF of 50,000 hours, that would be different.

Shit, I'd generally be happy with 2000 hours MTBF.
Click to expand...
Less than 12 weeks? You have a bright potential future with Samsung,
HP etc.
 
Spehro Pefhany wrote:

Eeyore <rabbitsfriendsandrelations@hotmail.com> wrote:
Spehro Pefhany wrote:
Mike Tomlinson <mike@jasper.org.uk> wrote:
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> writes

I guess that would be a rather serious problem if the temperature
inside your computer case averaged 105°C = 221°F.

Seen a modern mainboard recently?

Certainly.

Voltage regulation MOSFETs with
heatsinks on, some with their own extractor fans? Heat coupled to the
capacitors by a few millimetres of thick copper PCB trace for excellent
heat conduction?

Have you put a thermocouple on the capacitors?

You need a themocouple and a suitable meter for that ! ;~)

Graham

Really? ;-)

Of course many, if not most, portable multimeters have type K
thermocouple inputs (of dubious accuracy, but good enough for this
sort of thing) and many are supplied with a bead thermocouple.
Click to expand...
Funnily enough, often some of the cheapest ones have the thermocouple input but
I used to keep a supply of type-K themocoouples anyway. I like keeping an eye
on temps.

Graham
 
I clean them moderately regularly. Plus I don't operate
in a very dusty environment.

Nor do I. This wasn't dust -- it was more like gobs of
sub-microscopic carbon particles.

Never seen that. On the CPU cooler itself you mean?
Click to expand...
On the heat-sink. It reminded me of the black stuff that comes off a CRT
faceplate. Only a lot more.
 
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