R
Ron(UK)
Guest
Terry wrote:
Ron(UK)
Ron(UK)
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Jeff Liebermann
Guest
"Terry" <terryREMOVE@tbean.freeserve.co.uk> hath wroth:
they catch fire and burn. It's quite impressive. You can accellerate
the process by reversing the voltage across the tantalum. Try it.
Just take a random small tanatalum and put it across a power supply.
First, it starts to get hot. Then it glows red. Finally, it bursts
into flames and spews toxic smoke. It does take a while to break
down. I've had the polarity reversed for perhaps 3 hours before it
flamed out.
The 2V headway is not for noise spikes. It's to derate the capacitor
voltage specification at high temperatures to extend the lifetime.
Reliability of Capacitors
<http://www.illinoiscapacitor.com/uploads/papers_application/85560DAA867C4AE2871F2EFA1749A6C7.pdf>
<http://www.illinoiscapacitor.com/techcenter/lifecalculators.asp>
The upper calculator is for electrolytics.
The primary cause of short lifetime is temperature (and self heating),
but insufficient voltage derating is a close second. Note that at
rated voltage and temperature, the lifetime of an electrolytic is
specified at either 1,000 or 10,000 hrs, depending on service type.
That's not very long. The designed is expected to derate the applied
voltage and operating temperature in order to extend the lifetime. A
2:1 derating will be good for a lifetime of about 15 years. A 2v out
of perhaps 15v derating, might be good enough to barely make it
through the warranty period.
--
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
Tantalums are quite different. Exceed the voltage specification andDoes the 2v headway allow for noise spikes. Tants often fail this way.
they catch fire and burn. It's quite impressive. You can accellerate
the process by reversing the voltage across the tantalum. Try it.
Just take a random small tanatalum and put it across a power supply.
First, it starts to get hot. Then it glows red. Finally, it bursts
into flames and spews toxic smoke. It does take a while to break
down. I've had the polarity reversed for perhaps 3 hours before it
flamed out.
The 2V headway is not for noise spikes. It's to derate the capacitor
voltage specification at high temperatures to extend the lifetime.
Reliability of Capacitors
<http://www.illinoiscapacitor.com/uploads/papers_application/85560DAA867C4AE2871F2EFA1749A6C7.pdf>
<http://www.illinoiscapacitor.com/techcenter/lifecalculators.asp>
The upper calculator is for electrolytics.
The primary cause of short lifetime is temperature (and self heating),
but insufficient voltage derating is a close second. Note that at
rated voltage and temperature, the lifetime of an electrolytic is
specified at either 1,000 or 10,000 hrs, depending on service type.
That's not very long. The designed is expected to derate the applied
voltage and operating temperature in order to extend the lifetime. A
2:1 derating will be good for a lifetime of about 15 years. A 2v out
of perhaps 15v derating, might be good enough to barely make it
through the warranty period.
--
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
R
Ron(UK)
Guest
Arfa Daily wrote:
I spent many years repairing vcrs, audio, and microwave ovens made by
Philips.
As I`m sure you know, they used a totally unique system in their later
video recorder transport, fairly reliable, heads wore out fast, but the
majority of problems were 'casebook' so a good little earner there.
Philips microwave ovens were good, again unconventional in some ways and
prone to recurring faults, so again a money spinner... erm.. I'm
starting to like Philips gear, it`s made me a few bob over the years!
I was never a fan of their 'moving coil' cd player mechanism, but I
guess it was early days for the technology.
Philips washers and dryers were jolly good for business in their way,
plenty of easy stock faults and easy availability of spares. another
bunce earner
So, lemme see, recently gone to the great landfill in the sky are a
Philips freeview receiver B.E.R due to some logic problem (again I
understand this is a well know fault but non the less unrepairable),
a just out of guarantee Philips DVD/Hard/Disk recorder - something in
the logic failed + DVD drive up the spout, such a clunker of a machine
anyway I wouldn`t spend any time trying to fix it.
Both those were my own equipment.
Also there were several DVD drives out of computers - I realise that
these probably weren`t made in the Philips factory, but they carry the
Philips brand name, and that`s what counts to the punter.
Anyhoo, I declared that I wouldn`t buy any Philips branded gear again,
and so far I`ve stuck to that.
Maybe I`m being unfair to Philips equipment, I dunno, the Philips stuff
I bought in the last few years has already gone to the tip and I have no
confidence in their products now. I imagine most of it is made in China?
Ron(UK)
together as the older gear."Ron(UK)" <ron@lunevalleyaudio.com> wrote in message
news:LISdnRIxGcuRJ9zanZ2dnUVZ8hmdnZ2d@bt.com...
Terry wrote:
"Thomas Tornblom" <thomas@Hax.SE> wrote in message
news:x08x4uuwdx.fsf@Hax.SE...
Personally I avoid anything Philips, if I can.
Agreed.
I also have to agree, Philips have some odd ways of doing things.
Ron(UK)
I'll second that, Ron. But back on the original point of reliability, have
you ever had cause here in the UK to consider Philips gear to be
particularly badly built, or unreliable in any way, compared to other makes
? I wouldn't say that I actually have, certainly not to the point that Mark
Z and other US posters seem to have done. Perhaps there is some fundamental
difference between Philips products for the US market, and those for the
European market, given that Philips is fundamentally a European company,
being based in Holland. Interesting ...
Arfa
I'm only going off the newer stuff. maybe that`s not as well put
I spent many years repairing vcrs, audio, and microwave ovens made by
Philips.
As I`m sure you know, they used a totally unique system in their later
video recorder transport, fairly reliable, heads wore out fast, but the
majority of problems were 'casebook' so a good little earner there.
Philips microwave ovens were good, again unconventional in some ways and
prone to recurring faults, so again a money spinner... erm.. I'm
starting to like Philips gear, it`s made me a few bob over the years!
I was never a fan of their 'moving coil' cd player mechanism, but I
guess it was early days for the technology.
Philips washers and dryers were jolly good for business in their way,
plenty of easy stock faults and easy availability of spares. another
bunce earner
So, lemme see, recently gone to the great landfill in the sky are a
Philips freeview receiver B.E.R due to some logic problem (again I
understand this is a well know fault but non the less unrepairable),
a just out of guarantee Philips DVD/Hard/Disk recorder - something in
the logic failed + DVD drive up the spout, such a clunker of a machine
anyway I wouldn`t spend any time trying to fix it.
Both those were my own equipment.
Also there were several DVD drives out of computers - I realise that
these probably weren`t made in the Philips factory, but they carry the
Philips brand name, and that`s what counts to the punter.
Anyhoo, I declared that I wouldn`t buy any Philips branded gear again,
and so far I`ve stuck to that.
Maybe I`m being unfair to Philips equipment, I dunno, the Philips stuff
I bought in the last few years has already gone to the tip and I have no
confidence in their products now. I imagine most of it is made in China?
Ron(UK)
H
hr(bob) hofmann@att.net
Guest
On Nov 18, 11:50 pm, Smitty Two <prestwh...@earthlink.net> wrote:
Bob Hofmann
OK - Which brand(s) woukld you recommmend??In article
19f92502-06a0-40d4-8ba2-87a51942e...@b15g2000hsa.googlegroups.com>,
"hr(bob) hofm...@att.net" <hrhofm...@att.net> wrote:
I need to get a cheap DVD player for a rental property. I have a
choice of a Philips or a Memorex DVD player for $24.99 USD. Anyone
have any thoughts/printable comments about which might be more
reliable?
Bob Hofmann
How much is your time worth? Why not get something that will last longer
than three months, and save yourself the trouble of constantly replacing
it?
Bob Hofmann
A
Andy Cuffe
Guest
On Mon, 19 Nov 2007 01:03:41 GMT, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:
Philips. The quality of the boards and components was similar to a $9
clock radio. There were also lots of firmware bugs which made it
almost unusable (and there were no updates available). When I got
tired of it I ended up throwing it away rather than donating it (I
didn't want anyone else to waste money of it).
Andy Cuffe
acuffe@gmail.com
<arfa.daily@ntlworld.com> wrote:
I used to have a recent Philips DVD player and it was not made byAlthough Philips stuff may not be the most pleasant to work on, and their
service info sucks, I have found it in general to be quite well built, and
reasonably reliable. Iam interested in what negative experiences you might
have had to make you feel that it is "the worst" ?? Do you feel that the
Memorex would be a better bet? We might be seeing a difference in products
here between the US and UK.
Arfa
Philips. The quality of the boards and components was similar to a $9
clock radio. There were also lots of firmware bugs which made it
almost unusable (and there were no updates available). When I got
tired of it I ended up throwing it away rather than donating it (I
didn't want anyone else to waste money of it).
Andy Cuffe
acuffe@gmail.com
J
Jeff Liebermann
Guest
"Arfa Daily" <arfa.daily@ntlworld.com> hath wroth:
reliable products.
Once upon a time, I was doing design reviews for a manufacturer of
consumer electronics. For those not familiar with the term "design
review", it's an ordeal process, where an outside authority is paid to
shoot holes in a pre-production design, with the specific purpose of
finding screwups, catching oversights, reducing costs, and generally
making the life of the designers miserable.
State of the art in component selection and computer modeling had
progressed to the point where it is possible to predict component
failure rates given known operating conditions. The capacitor
formulas at:
<http://www.illinoiscapacitor.com/techcenter/lifecalculators.asp>
are what is used. Note that the lifetime for electrolytics operating
at maximum ratings is only about 1000 hrs:
<http://www.illinoiscapacitor.com/products/aluminum.asp>
There are similar models for semiconductors based on thermal cycles
and power components based on simple entropy. Given years of
experience with a war chest of standard components, additional data
can be added to the mix.
My part of the puzzle wasn't in the failure prediction department, but
I watched the process evolve over the years. At one point, the
manufactory could estimate the point at which the largest number of
field failures would occur and target their stocking, warranties, and
replacement products accordingly. For example, if the calculations
showed that units sold on introduction will begin to fail after 3
years, then the warranty will be less than 3 years, and a replacement
product will be available at the 3 year mark. Under ideal
circumstances, everything will fail at once. This method gets the
product closer to this ideal.
In grinding the numbers, a simple spreadsheet was used for capacitors.
I may have a copy somewhere but don't want to leak someone else's
work. If I get ambitious, I'll recreate it. Anyway, the result is an
estimate of capacitor lifetime based on known operating conditions. If
the target lifetime is 3 years (26,000 hrs), then any capacitor that
shows a calculated longer lifetime is considered over-rated and is a
potential waste of valuable pennies to the bean counters. Once
identified, the size and voltage ratings are reduced downwards to fit
the predicted lifetimes.
In the distant past, there was an advantage to using as many
capacitors of the same exact value as possible to increase quantity
discounts and reduce handling overhead. With bulk lot purchasing and
robot assembly, this is no longer the case. It's perfectly acceptable
to have a wide variety of electrolytic sizes, values, and voltages
without impacting the cost. The result are boards stuffed with 3v,
4v, 6.3v, 8v, 10v, 12v, 15v, 16v, 18v, 25v, etc capacitors with almost
identical capacitance values. Such boards are easy to spot and should
give you a clue as to the degree of penny pinching that was required
to cut costs. If you have a product on the bench to repair and a wide
assortment of capacitors are apparently dead, don't assume user abuse.
It might be that they were sized specifically to all fail
simultaneously.
Anyway, I don't have much experience fixing DVD players or with
Philips products. I do have a Philips DVDR 995 DVD recorder, which
trashes most DVD-R's it tried to burn, and now refuses to play other
home burned DVD's, although it will play most commercial DVD's.
Probably a dying laser. It also has a rather oddly designed remote
control that also eats batteries. It was given to me with the warning
"It's crap" which I have personally verified. It would be at the
local thrift shop or recyclers were it not at the very bottom of my
equipment pile and therefore difficult to extract. Caveat Emptor.
--
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
Personally, I feel vindictive. Time to rant some more on the topic ofJeff and James.
Thank you gentlemen. I feel vindicated ...
reliable products.
Once upon a time, I was doing design reviews for a manufacturer of
consumer electronics. For those not familiar with the term "design
review", it's an ordeal process, where an outside authority is paid to
shoot holes in a pre-production design, with the specific purpose of
finding screwups, catching oversights, reducing costs, and generally
making the life of the designers miserable.
State of the art in component selection and computer modeling had
progressed to the point where it is possible to predict component
failure rates given known operating conditions. The capacitor
formulas at:
<http://www.illinoiscapacitor.com/techcenter/lifecalculators.asp>
are what is used. Note that the lifetime for electrolytics operating
at maximum ratings is only about 1000 hrs:
<http://www.illinoiscapacitor.com/products/aluminum.asp>
There are similar models for semiconductors based on thermal cycles
and power components based on simple entropy. Given years of
experience with a war chest of standard components, additional data
can be added to the mix.
My part of the puzzle wasn't in the failure prediction department, but
I watched the process evolve over the years. At one point, the
manufactory could estimate the point at which the largest number of
field failures would occur and target their stocking, warranties, and
replacement products accordingly. For example, if the calculations
showed that units sold on introduction will begin to fail after 3
years, then the warranty will be less than 3 years, and a replacement
product will be available at the 3 year mark. Under ideal
circumstances, everything will fail at once. This method gets the
product closer to this ideal.
In grinding the numbers, a simple spreadsheet was used for capacitors.
I may have a copy somewhere but don't want to leak someone else's
work. If I get ambitious, I'll recreate it. Anyway, the result is an
estimate of capacitor lifetime based on known operating conditions. If
the target lifetime is 3 years (26,000 hrs), then any capacitor that
shows a calculated longer lifetime is considered over-rated and is a
potential waste of valuable pennies to the bean counters. Once
identified, the size and voltage ratings are reduced downwards to fit
the predicted lifetimes.
In the distant past, there was an advantage to using as many
capacitors of the same exact value as possible to increase quantity
discounts and reduce handling overhead. With bulk lot purchasing and
robot assembly, this is no longer the case. It's perfectly acceptable
to have a wide variety of electrolytic sizes, values, and voltages
without impacting the cost. The result are boards stuffed with 3v,
4v, 6.3v, 8v, 10v, 12v, 15v, 16v, 18v, 25v, etc capacitors with almost
identical capacitance values. Such boards are easy to spot and should
give you a clue as to the degree of penny pinching that was required
to cut costs. If you have a product on the bench to repair and a wide
assortment of capacitors are apparently dead, don't assume user abuse.
It might be that they were sized specifically to all fail
simultaneously.
Anyway, I don't have much experience fixing DVD players or with
Philips products. I do have a Philips DVDR 995 DVD recorder, which
trashes most DVD-R's it tried to burn, and now refuses to play other
home burned DVD's, although it will play most commercial DVD's.
Probably a dying laser. It also has a rather oddly designed remote
control that also eats batteries. It was given to me with the warning
"It's crap" which I have personally verified. It would be at the
local thrift shop or recyclers were it not at the very bottom of my
equipment pile and therefore difficult to extract. Caveat Emptor.
--
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
J
Jeff Liebermann
Guest
"hr(bob) hofmann@att.net" <hrhofmann@att.net> hath wroth:
manufacturers do not make their own products. They buy container
loads of product from Chinese vendors, and put their name on the
product. If really ambitious, they might document it, but normally,
all they do is stuff the white box into an impressive and gaudy retail
package. It's sometime difficult to contact the manufacturer or get
them to admit they imported the product.
The result is that you never know what you're getting. The quality
varies from dismal to impressive. I bought a no-name DVD player at
Kmart as a present. I think I paid $35 for it 3 years ago. It was a
gift for a 12 year old brat with a marked tendency to destroy
everything he touches. It's still working perfectly today, although
I've rebuilt the remote control twice. On the other hand, one of my
customers was giving presentations at Rotary Club meetings. I
convinced him that using a laptop for playing a short DVD movie was
overkill, and had him buy a DVD player. It was a Magnavox which
lasted about 60 days and died. The warranty was 30 days.
If you want to do the necessary research, it's possible to get a clue
as to the quality by looking at the guts on the FCC ID web pile. Look
at the serial number tag and extract the FCC ID number. Then go unto:
<https://fjallfoss.fcc.gov/oetcf/eas/reports/GenericSearch.cfm>
and find the listing. You may have to play with the format of the
"product code" as some entries start with a "-" or space. The inside
photos should give you a clue as to what you're buying. If it looks
like junk components, get something else.
If you insist on shopping by brand, I've had good luck with Panasonic
and Toshiba. However, there's no guarantee that they didn't just
stick their name on some piece of white box junk. At the bottom of
the barrel, I've had a history of weird problems with Sony. Sorry,
but not much experience with anything else.
Drivel: Do you supply a DVD player for your tenants? When I had my
rental, I wouldn't even give them the time of day, much less a free
DVD player. For a rental, anything will suffice, preferably the
cheapest, since it's assume they'll either destroy or steal it.
Drivel 2.0: No change on the local solar powered RFI generator front
because everyone is too busy to do anything useful. Sigh.
--
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
Bad question. At that price level, even the so called name brandOn Nov 18, 11:50 pm, Smitty Two <prestwh...@earthlink.net> wrote:
In article
19f92502-06a0-40d4-8ba2-87a51942e...@b15g2000hsa.googlegroups.com>,
"hr(bob) hofm...@att.net" <hrhofm...@att.net> wrote:
I need to get a cheap DVD player for a rental property. I have a
choice of a Philips or a Memorex DVD player for $24.99 USD. Anyone
have any thoughts/printable comments about which might be more
reliable?
Bob Hofmann
How much is your time worth? Why not get something that will last longer
than three months, and save yourself the trouble of constantly replacing
it?
OK - Which brand(s) woukld you recommmend??
Bob Hofmann
manufacturers do not make their own products. They buy container
loads of product from Chinese vendors, and put their name on the
product. If really ambitious, they might document it, but normally,
all they do is stuff the white box into an impressive and gaudy retail
package. It's sometime difficult to contact the manufacturer or get
them to admit they imported the product.
The result is that you never know what you're getting. The quality
varies from dismal to impressive. I bought a no-name DVD player at
Kmart as a present. I think I paid $35 for it 3 years ago. It was a
gift for a 12 year old brat with a marked tendency to destroy
everything he touches. It's still working perfectly today, although
I've rebuilt the remote control twice. On the other hand, one of my
customers was giving presentations at Rotary Club meetings. I
convinced him that using a laptop for playing a short DVD movie was
overkill, and had him buy a DVD player. It was a Magnavox which
lasted about 60 days and died. The warranty was 30 days.
If you want to do the necessary research, it's possible to get a clue
as to the quality by looking at the guts on the FCC ID web pile. Look
at the serial number tag and extract the FCC ID number. Then go unto:
<https://fjallfoss.fcc.gov/oetcf/eas/reports/GenericSearch.cfm>
and find the listing. You may have to play with the format of the
"product code" as some entries start with a "-" or space. The inside
photos should give you a clue as to what you're buying. If it looks
like junk components, get something else.
If you insist on shopping by brand, I've had good luck with Panasonic
and Toshiba. However, there's no guarantee that they didn't just
stick their name on some piece of white box junk. At the bottom of
the barrel, I've had a history of weird problems with Sony. Sorry,
but not much experience with anything else.
Drivel: Do you supply a DVD player for your tenants? When I had my
rental, I wouldn't even give them the time of day, much less a free
DVD player. For a rental, anything will suffice, preferably the
cheapest, since it's assume they'll either destroy or steal it.
Drivel 2.0: No change on the local solar powered RFI generator front
because everyone is too busy to do anything useful. Sigh.
--
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
A
Arfa Daily
Guest
"Andy Cuffe" <acuffe@gmail.com> wrote in message
news:0lr3k39aji9mue2r8i6uv8bn66h9204co9@4ax.com...
have said was actually made by them. They have a distinct 'Philips-ness'
about them, and it would be very easy to say, when taking one to bits, "that
doesn't look like a Philips ..." if indeed it didn't. So perhaps they do
reserve stuff that they make themselves for the 'home' market, and badge
stuff of other manufacture, for the US market. I suppose it could be
something to do with import restrictions or duties or even for some
'political' reason. I have a friend who works for a company that carry out
exclusively Philips service. I'll give him a call, and see if they see stuff
that isn't of native Philips manufacture.
Arfa
> acuffe@gmail.com
news:0lr3k39aji9mue2r8i6uv8bn66h9204co9@4ax.com...
hifi and DVD - and I can't recall ever seeing an item that you would notOn Mon, 19 Nov 2007 01:03:41 GMT, "Arfa Daily"
arfa.daily@ntlworld.com> wrote:
Although Philips stuff may not be the most pleasant to work on, and their
service info sucks, I have found it in general to be quite well built, and
reasonably reliable. Iam interested in what negative experiences you might
have had to make you feel that it is "the worst" ?? Do you feel that the
Memorex would be a better bet? We might be seeing a difference in products
here between the US and UK.
Arfa
I used to have a recent Philips DVD player and it was not made by
Philips. The quality of the boards and components was similar to a $9
clock radio. There were also lots of firmware bugs which made it
almost unusable (and there were no updates available). When I got
tired of it I ended up throwing it away rather than donating it (I
didn't want anyone else to waste money of it).
Andy Cuffe
That's interesting Andy. I see a reasonable amount of Philips stuff - mainly
have said was actually made by them. They have a distinct 'Philips-ness'
about them, and it would be very easy to say, when taking one to bits, "that
doesn't look like a Philips ..." if indeed it didn't. So perhaps they do
reserve stuff that they make themselves for the 'home' market, and badge
stuff of other manufacture, for the US market. I suppose it could be
something to do with import restrictions or duties or even for some
'political' reason. I have a friend who works for a company that carry out
exclusively Philips service. I'll give him a call, and see if they see stuff
that isn't of native Philips manufacture.
Arfa
> acuffe@gmail.com
B
b
Guest
On Nov 19, 7:27 pm, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
have been numerous widespread problems (albeit in a narrow range of
stuff.)
-faulty tubes: W56ECK001X04, (chassis L01.1E) W66ECK001X14, etc.
-painter chips: chassis, A10 /E
-dvd recorder pickups dropping like flies (in most other and cheaper
makes i find the power supplies to go first!)
all of which are serious expensive problems which can mean a write
off. Not funny in such new equipment.
Apart from that though, I usually find the build quality to be pretty
good. I personally still have a 16 year old 28GR9772 working superbly
in the bedroom and a VR632 which has only had the usual minor plastic
cog problem as with most turbo decks. Most of the Philips Tvs I get
asked to repair apart from the above listed known 'dogs' are still
serviceable, even the likes of CP90 and CP110. but I digress.
to get back on topic to the dvd discussion, I would stick with the
philips being a more well known name, but must echo what others have
said, i.e. at that price point you're going to get cheap and nasty
stuff in any case. You get what you pay for. Anyone worried about
reliability would be well advised just to skip that price bracket.
-B
it varies, but in terms of reliability over the last few years thereI'll second that, Ron. But back on the original point of reliability, have
you ever had cause here in the UK to consider Philips gear to be
particularly badly built, or unreliable in any way, compared to other makes
have been numerous widespread problems (albeit in a narrow range of
stuff.)
-faulty tubes: W56ECK001X04, (chassis L01.1E) W66ECK001X14, etc.
-painter chips: chassis, A10 /E
-dvd recorder pickups dropping like flies (in most other and cheaper
makes i find the power supplies to go first!)
all of which are serious expensive problems which can mean a write
off. Not funny in such new equipment.
Apart from that though, I usually find the build quality to be pretty
good. I personally still have a 16 year old 28GR9772 working superbly
in the bedroom and a VR632 which has only had the usual minor plastic
cog problem as with most turbo decks. Most of the Philips Tvs I get
asked to repair apart from the above listed known 'dogs' are still
serviceable, even the likes of CP90 and CP110. but I digress.
to get back on topic to the dvd discussion, I would stick with the
philips being a more well known name, but must echo what others have
said, i.e. at that price point you're going to get cheap and nasty
stuff in any case. You get what you pay for. Anyone worried about
reliability would be well advised just to skip that price bracket.
-B
A
Arfa Daily
Guest
"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:upt3k358rpbv4htkslvgt2ie7te7btnc61@4ax.com...
failures of caps that I often experience. It also answers for Graham, as to
why he is wrong with his contention that a cap can be run to its voltage
limit, with no ill effects. It also explains why you are absolutely spot on
about different voltage ratings of caps with the same values in the same
equipment. I have come across this many times and wondered why, when they
were using a 25v cap in one position, they then used a 16v one of the same
value elsewhere, even though the physical sizes are similar, and you would
have imagined that they could have got a better deal by buying twice as many
of a single type. Good stuff.
Arfa
news:upt3k358rpbv4htkslvgt2ie7te7btnc61@4ax.com...
That's highly enlightening, and goes a long way to explaining the multiple"Arfa Daily" <arfa.daily@ntlworld.com> hath wroth:
Jeff and James.
Thank you gentlemen. I feel vindicated ...
Personally, I feel vindictive. Time to rant some more on the topic of
reliable products.
Once upon a time, I was doing design reviews for a manufacturer of
consumer electronics. For those not familiar with the term "design
review", it's an ordeal process, where an outside authority is paid to
shoot holes in a pre-production design, with the specific purpose of
finding screwups, catching oversights, reducing costs, and generally
making the life of the designers miserable.
State of the art in component selection and computer modeling had
progressed to the point where it is possible to predict component
failure rates given known operating conditions. The capacitor
formulas at:
http://www.illinoiscapacitor.com/techcenter/lifecalculators.asp
are what is used. Note that the lifetime for electrolytics operating
at maximum ratings is only about 1000 hrs:
http://www.illinoiscapacitor.com/products/aluminum.asp
There are similar models for semiconductors based on thermal cycles
and power components based on simple entropy. Given years of
experience with a war chest of standard components, additional data
can be added to the mix.
My part of the puzzle wasn't in the failure prediction department, but
I watched the process evolve over the years. At one point, the
manufactory could estimate the point at which the largest number of
field failures would occur and target their stocking, warranties, and
replacement products accordingly. For example, if the calculations
showed that units sold on introduction will begin to fail after 3
years, then the warranty will be less than 3 years, and a replacement
product will be available at the 3 year mark. Under ideal
circumstances, everything will fail at once. This method gets the
product closer to this ideal.
In grinding the numbers, a simple spreadsheet was used for capacitors.
I may have a copy somewhere but don't want to leak someone else's
work. If I get ambitious, I'll recreate it. Anyway, the result is an
estimate of capacitor lifetime based on known operating conditions. If
the target lifetime is 3 years (26,000 hrs), then any capacitor that
shows a calculated longer lifetime is considered over-rated and is a
potential waste of valuable pennies to the bean counters. Once
identified, the size and voltage ratings are reduced downwards to fit
the predicted lifetimes.
In the distant past, there was an advantage to using as many
capacitors of the same exact value as possible to increase quantity
discounts and reduce handling overhead. With bulk lot purchasing and
robot assembly, this is no longer the case. It's perfectly acceptable
to have a wide variety of electrolytic sizes, values, and voltages
without impacting the cost. The result are boards stuffed with 3v,
4v, 6.3v, 8v, 10v, 12v, 15v, 16v, 18v, 25v, etc capacitors with almost
identical capacitance values. Such boards are easy to spot and should
give you a clue as to the degree of penny pinching that was required
to cut costs. If you have a product on the bench to repair and a wide
assortment of capacitors are apparently dead, don't assume user abuse.
It might be that they were sized specifically to all fail
simultaneously.
Anyway, I don't have much experience fixing DVD players or with
Philips products. I do have a Philips DVDR 995 DVD recorder, which
trashes most DVD-R's it tried to burn, and now refuses to play other
home burned DVD's, although it will play most commercial DVD's.
Probably a dying laser. It also has a rather oddly designed remote
control that also eats batteries. It was given to me with the warning
"It's crap" which I have personally verified. It would be at the
local thrift shop or recyclers were it not at the very bottom of my
equipment pile and therefore difficult to extract. Caveat Emptor.
failures of caps that I often experience. It also answers for Graham, as to
why he is wrong with his contention that a cap can be run to its voltage
limit, with no ill effects. It also explains why you are absolutely spot on
about different voltage ratings of caps with the same values in the same
equipment. I have come across this many times and wondered why, when they
were using a 25v cap in one position, they then used a 16v one of the same
value elsewhere, even though the physical sizes are similar, and you would
have imagined that they could have got a better deal by buying twice as many
of a single type. Good stuff.
Arfa
H
hr(bob) hofmann@att.net
Guest
On Nov 19, 7:30 pm, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
dvd player, since it had a 1-yr warranty on parts and labor and the
competition only had 90 days parts and labor. Brought it home and
hooked it up, actually followed some fairly clear instructions just to
see how good they were. Must have been written by someone with
English as a first language, because the English actually made sense,
without the usual stilted words. Turned it on and it worked just
fine.
Decided to use my older dvd at the rental and keep the new one here at
my home. BTW, the rental unit is only loaned out to ski friends who
don't trash it if they want to be allowed to rent it again. So I
don't worrry about problems with tenants like I would if it were a
regular ski rental.
Thanks for all the civil discussion this generated.
H. R.(Bob) Hofmann
Well, I looked at a couple of units and decided to go with the Philips"Jeff Liebermann" <je...@cruzio.com> wrote in message
news:upt3k358rpbv4htkslvgt2ie7te7btnc61@4ax.com...
"Arfa Daily" <arfa.da...@ntlworld.com> hath wroth:
Jeff and James.
Thank you gentlemen. I feel vindicated ...
Personally, I feel vindictive. Time to rant some more on the topic of
reliable products.
Once upon a time, I was doing design reviews for a manufacturer of
consumer electronics. For those not familiar with the term "design
review", it's an ordeal process, where an outside authority is paid to
shoot holes in a pre-production design, with the specific purpose of
finding screwups, catching oversights, reducing costs, and generally
making the life of the designers miserable.
State of the art in component selection and computer modeling had
progressed to the point where it is possible to predict component
failure rates given known operating conditions. The capacitor
formulas at:
http://www.illinoiscapacitor.com/techcenter/lifecalculators.asp
are what is used. Note that the lifetime for electrolytics operating
at maximum ratings is only about 1000 hrs:
http://www.illinoiscapacitor.com/products/aluminum.asp
There are similar models for semiconductors based on thermal cycles
and power components based on simple entropy. Given years of
experience with a war chest of standard components, additional data
can be added to the mix.
My part of the puzzle wasn't in the failure prediction department, but
I watched the process evolve over the years. At one point, the
manufactory could estimate the point at which the largest number of
field failures would occur and target their stocking, warranties, and
replacement products accordingly. For example, if the calculations
showed that units sold on introduction will begin to fail after 3
years, then the warranty will be less than 3 years, and a replacement
product will be available at the 3 year mark. Under ideal
circumstances, everything will fail at once. This method gets the
product closer to this ideal.
In grinding the numbers, a simple spreadsheet was used for capacitors.
I may have a copy somewhere but don't want to leak someone else's
work. If I get ambitious, I'll recreate it. Anyway, the result is an
estimate of capacitor lifetime based on known operating conditions. If
the target lifetime is 3 years (26,000 hrs), then any capacitor that
shows a calculated longer lifetime is considered over-rated and is a
potential waste of valuable pennies to the bean counters. Once
identified, the size and voltage ratings are reduced downwards to fit
the predicted lifetimes.
In the distant past, there was an advantage to using as many
capacitors of the same exact value as possible to increase quantity
discounts and reduce handling overhead. With bulk lot purchasing and
robot assembly, this is no longer the case. It's perfectly acceptable
to have a wide variety of electrolytic sizes, values, and voltages
without impacting the cost. The result are boards stuffed with 3v,
4v, 6.3v, 8v, 10v, 12v, 15v, 16v, 18v, 25v, etc capacitors with almost
identical capacitance values. Such boards are easy to spot and should
give you a clue as to the degree of penny pinching that was required
to cut costs. If you have a product on the bench to repair and a wide
assortment of capacitors are apparently dead, don't assume user abuse.
It might be that they were sized specifically to all fail
simultaneously.
Anyway, I don't have much experience fixing DVD players or with
Philips products. I do have a Philips DVDR 995 DVD recorder, which
trashes most DVD-R's it tried to burn, and now refuses to play other
home burned DVD's, although it will play most commercial DVD's.
Probably a dying laser. It also has a rather oddly designed remote
control that also eats batteries. It was given to me with the warning
"It's crap" which I have personally verified. It would be at the
local thrift shop or recyclers were it not at the very bottom of my
equipment pile and therefore difficult to extract. Caveat Emptor.
That's highly enlightening, and goes a long way to explaining the multiple
failures of caps that I often experience. It also answers for Graham, as to
why he is wrong with his contention that a cap can be run to its voltage
limit, with no ill effects. It also explains why you are absolutely spot on
about different voltage ratings of caps with the same values in the same
equipment. I have come across this many times and wondered why, when they
were using a 25v cap in one position, they then used a 16v one of the same
value elsewhere, even though the physical sizes are similar, and you would
have imagined that they could have got a better deal by buying twice as many
of a single type. Good stuff.
Arfa- Hide quoted text -
- Show quoted text -
dvd player, since it had a 1-yr warranty on parts and labor and the
competition only had 90 days parts and labor. Brought it home and
hooked it up, actually followed some fairly clear instructions just to
see how good they were. Must have been written by someone with
English as a first language, because the English actually made sense,
without the usual stilted words. Turned it on and it worked just
fine.
Decided to use my older dvd at the rental and keep the new one here at
my home. BTW, the rental unit is only loaned out to ski friends who
don't trash it if they want to be allowed to rent it again. So I
don't worrry about problems with tenants like I would if it were a
regular ski rental.
Thanks for all the civil discussion this generated.
H. R.(Bob) Hofmann
A
Arfa Daily
Guest
<snip>
Brought it home and
Philips are actually a Dutch company, so that's probably where the manual
originated. Interestingly though, the Dutch people speak English almost as
well as English people. I can easily work most of the near-European
countries on the radio, and it is always a pleasure to speak to the Dutch,
as they understand colloquial English and jokes just as any native English
speaker would. OTOH, if speaking to a German or French or Belgian ham for
instance, although they speak very good English - certainly much better than
I could speak their languages - I always find it necessary to keep it very
straightforward and 'text book'.
I once saw something that explained this as being to do with their proximity
to England, and their low-lying land, combining to give them good TV
coverage on UHF from south coast UK TV transmitters, so they grow up
watching UK / American TV as a 'free' supplement to their own. Is that just
the best example ever of a whole country being influenced by the power of TV
? I wonder if their ability to speak better English than their neighbours,
will decline when it all goes totally digital, and only the low power
transmitters are left here, which will probably struggle to make the trip to
Holland ?
Arfa
Brought it home and
<snip>hooked it up, actually followed some fairly clear instructions just to
see how good they were. Must have been written by someone with
English as a first language, because the English actually made sense,
without the usual stilted words.
Philips are actually a Dutch company, so that's probably where the manual
originated. Interestingly though, the Dutch people speak English almost as
well as English people. I can easily work most of the near-European
countries on the radio, and it is always a pleasure to speak to the Dutch,
as they understand colloquial English and jokes just as any native English
speaker would. OTOH, if speaking to a German or French or Belgian ham for
instance, although they speak very good English - certainly much better than
I could speak their languages - I always find it necessary to keep it very
straightforward and 'text book'.
I once saw something that explained this as being to do with their proximity
to England, and their low-lying land, combining to give them good TV
coverage on UHF from south coast UK TV transmitters, so they grow up
watching UK / American TV as a 'free' supplement to their own. Is that just
the best example ever of a whole country being influenced by the power of TV
? I wonder if their ability to speak better English than their neighbours,
will decline when it all goes totally digital, and only the low power
transmitters are left here, which will probably struggle to make the trip to
Holland ?
Arfa
T
Thomas Tornblom
Guest
I believe a big factor is having TV with subtitles instead of dubbing.
I think this is true for most smaller countries.
I think this is true for most smaller countries.
J
JW
Guest
On Mon, 19 Nov 2007 09:37:33 -0800 Jeff Liebermann <jeffl@cruzio.com>
wrote in Message id: <37h3k35aulhlpfpgktob56pg2agv7fvhps@4ax.com>:
polarity on the silkscreen was incorrect, causing the tantalum caps to be
installed backwards. Some of the boards ran 24/7 for 3 to 4 months of
operation before catching fire.
wrote in Message id: <37h3k35aulhlpfpgktob56pg2agv7fvhps@4ax.com>:
Hell, a few or ten years ago we had actually shipped product where theTantalums are quite different. Exceed the voltage specification and
they catch fire and burn. It's quite impressive. You can accellerate
the process by reversing the voltage across the tantalum. Try it.
Just take a random small tanatalum and put it across a power supply.
First, it starts to get hot. Then it glows red. Finally, it bursts
into flames and spews toxic smoke. It does take a while to break
down. I've had the polarity reversed for perhaps 3 hours before it
flamed out.
polarity on the silkscreen was incorrect, causing the tantalum caps to be
installed backwards. Some of the boards ran 24/7 for 3 to 4 months of
operation before catching fire.
J
JW
Guest
On Mon, 19 Nov 2007 18:03:23 GMT "James Sweet" <jamessweet@hotmail.com>
wrote in Message id: <Ldk0j.7690$B21.1714@trndny07>:
vintage HP test equipment. The guy pops into the thread ranting and
screaming at me about how different types of wire would not effect the
quality of sound from a stereo system. Sheesh.
wrote in Message id: <Ldk0j.7690$B21.1714@trndny07>:
Thirded. I've been repairing electronics equipment for 20+ years.We've had this conversation before Graham. As a service engineer, which
you, I think, are not, I can only go by experience. The caps which
regularly fail, are (most) always rated just a couple of volts above what
they are actually running at. Now I know full well that you believe this
to be a nonsense, but I'm sure that anyone else on here who is regularly
involved in actually repairing the stuff, will tell you the same. It might
be some kind of anomaly in your reckoning, or even not possible to your
mind. That doesn't alter the fact that it is true. It might just be a
physical size versus internal heat issue. I just don't know, but it is so,
whether you believe it or not.
Other than this, I don't want to get into the discussion, as it's not what
the thread is about, and the last thing we need is another one
degenerating into a ridiculous flame war, as you get madder and madder,
and all the usual suspects jump in to have a pop at you ...
Second that,
And ditto as well. I was once looking for a source on power cords for someI haven't seen much from that guy aside from inflamatory flame
posts.
vintage HP test equipment. The guy pops into the thread ranting and
screaming at me about how different types of wire would not effect the
quality of sound from a stereo system. Sheesh.
J
Jeff Liebermann
Guest
JW <none@dev.null> hath wroth:
few tanatalums backwards on the 5V power supply bus. The board worked
just fine for about a month of daily use. Then, I get a panic phone
call. "The computer is on fire. What do I do"? After careful
consideration of the situation for perhaps 100 milliseconds, I calmly
suggest they turn it off. I heard the loud "clunk" of the XT power
supply switch over the phone.
When I arrived, the culprit was obvious. There was a smoldering black
carbonized blob of charcoal where the tantalum should have been. I
couldn't resist applying power and watching it glow very bright red
and belch smoke. Was going to show everyone in the office the smoking
capacitor, but nobody seemed interested. So, I just cut it out of the
circuit board. I also looked around for more backwards capacitors,
but didn't find any. I don't recall if the silk screen was correct.
Incidentally, these were 10uf 15v caps on a 5v bus.
Later, I was curious if backwards tantalums could be thermally
detected. I applied reverse voltage and waited for the capacitor to
get hot. I had to apply more than the rated voltage to get it to
start heating. However, once it started to draw current and get warm,
it rapidly progressed towards burning. Thermal detection didn't work
because it took far too long to get hot.
Slight subject drift...
I had some difficulties with tantalums. I was dealing with a simple
voltage doubler power supply. For some reason, I decided to use
tantalum capacitors instead of the usual electrolytics. The result
was low output and far more ripple at the output than I would have
expected. I eventually found that I had a bag of defective tantalums
with very high ESR (as measured on my Dick Smith ESR meter).
Apparently, I wasn't the only person with the problem. See:
<http://ludens.cl/Electron/esr/esr.html>
to the right of the photo with the two yellow tantalums. I later
sample tested my small inventory, and but didn't find any more with
high ESR.
--
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
I had a similar experience. Ancient IBM XT clone motherboard with aOn Mon, 19 Nov 2007 09:37:33 -0800 Jeff Liebermann <jeffl@cruzio.com
wrote in Message id: <37h3k35aulhlpfpgktob56pg2agv7fvhps@4ax.com>:
Tantalums are quite different. Exceed the voltage specification and
they catch fire and burn. It's quite impressive. You can accellerate
the process by reversing the voltage across the tantalum. Try it.
Just take a random small tanatalum and put it across a power supply.
First, it starts to get hot. Then it glows red. Finally, it bursts
into flames and spews toxic smoke. It does take a while to break
down. I've had the polarity reversed for perhaps 3 hours before it
flamed out.
Hell, a few or ten years ago we had actually shipped product where the
polarity on the silkscreen was incorrect, causing the tantalum caps to be
installed backwards. Some of the boards ran 24/7 for 3 to 4 months of
operation before catching fire.
few tanatalums backwards on the 5V power supply bus. The board worked
just fine for about a month of daily use. Then, I get a panic phone
call. "The computer is on fire. What do I do"? After careful
consideration of the situation for perhaps 100 milliseconds, I calmly
suggest they turn it off. I heard the loud "clunk" of the XT power
supply switch over the phone.
When I arrived, the culprit was obvious. There was a smoldering black
carbonized blob of charcoal where the tantalum should have been. I
couldn't resist applying power and watching it glow very bright red
and belch smoke. Was going to show everyone in the office the smoking
capacitor, but nobody seemed interested. So, I just cut it out of the
circuit board. I also looked around for more backwards capacitors,
but didn't find any. I don't recall if the silk screen was correct.
Incidentally, these were 10uf 15v caps on a 5v bus.
Later, I was curious if backwards tantalums could be thermally
detected. I applied reverse voltage and waited for the capacitor to
get hot. I had to apply more than the rated voltage to get it to
start heating. However, once it started to draw current and get warm,
it rapidly progressed towards burning. Thermal detection didn't work
because it took far too long to get hot.
Slight subject drift...
I had some difficulties with tantalums. I was dealing with a simple
voltage doubler power supply. For some reason, I decided to use
tantalum capacitors instead of the usual electrolytics. The result
was low output and far more ripple at the output than I would have
expected. I eventually found that I had a bag of defective tantalums
with very high ESR (as measured on my Dick Smith ESR meter).
Apparently, I wasn't the only person with the problem. See:
<http://ludens.cl/Electron/esr/esr.html>
to the right of the photo with the two yellow tantalums. I later
sample tested my small inventory, and but didn't find any more with
high ESR.
--
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
F
Franc Zabkar
Guest
On Mon, 19 Nov 2007 08:50:51 +0000, Eeyore
<rabbitsfriendsandrelations@hotmail.com> put finger to keyboard and
composed:
I found the following datasheet useful because it discusses failure
rates for aluminium electrolytic capacitors:
NSP SERIES LOW ESR SOLID ALUMINUM ELECTROLYTIC CAPACITOR
http://www.niccomp.com/NSPAppGuide0503.pdf
There is a table at the end which represents a failure rate model as
outlined in MIL-HDBK-217, the Military Handbook for "Reliability
Prediction of Electronic Equipment".
The formula for failure rate (FR) is ...
FR = (BFR) x (temperature factor) x (voltage factor) x (capacitance
value factor)
BFR = Basic Failure Rate for Aluminum Electrolytic Capacitors (per
MIL-HDBK-217F)
FR is influenced by:
- temperature of operation
- applied voltage to voltage rating (voltage ratio factor)
- capacitance value factor
For example, the FR for a 1uF 100V electrolytic capacitor operating at
25C 30V is 1 x BFR.
The same cap operating at its rated voltage would have a 14x greater
failure rate. The voltage factors at voltage ratios of 0.6, 0.7, 0.8
and 0.9 are 2, 3.2, 5.2 and 8.6, respectively. This suggests to me
that any design that allowed for a 50% margin would be 5 times more
reliable than one that operated at rated voltages.
If typical "wet" electros follow the above pattern, then Arfa's
observations would be right on the money.
By comparison, solid electros (as used in current motherboards) appear
to be a *lot* more reliable and according to the datasheet suffer no
degradation in ESR, capacitance or leakage current after being
operated for 7000 hours at rated voltage and temperature (105C).
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
<rabbitsfriendsandrelations@hotmail.com> put finger to keyboard and
composed:
I'm aware that solid electros are not relevant to this discussion, butArfa Daily wrote:
they have tiny 85 deg caps fitted that are rated about 2 volts above what they
have to work at
There's nothing wrong with that voltage rating. Why do you think they have a
working voltage rating ?
Graham
I found the following datasheet useful because it discusses failure
rates for aluminium electrolytic capacitors:
NSP SERIES LOW ESR SOLID ALUMINUM ELECTROLYTIC CAPACITOR
http://www.niccomp.com/NSPAppGuide0503.pdf
There is a table at the end which represents a failure rate model as
outlined in MIL-HDBK-217, the Military Handbook for "Reliability
Prediction of Electronic Equipment".
The formula for failure rate (FR) is ...
FR = (BFR) x (temperature factor) x (voltage factor) x (capacitance
value factor)
BFR = Basic Failure Rate for Aluminum Electrolytic Capacitors (per
MIL-HDBK-217F)
FR is influenced by:
- temperature of operation
- applied voltage to voltage rating (voltage ratio factor)
- capacitance value factor
For example, the FR for a 1uF 100V electrolytic capacitor operating at
25C 30V is 1 x BFR.
The same cap operating at its rated voltage would have a 14x greater
failure rate. The voltage factors at voltage ratios of 0.6, 0.7, 0.8
and 0.9 are 2, 3.2, 5.2 and 8.6, respectively. This suggests to me
that any design that allowed for a 50% margin would be 5 times more
reliable than one that operated at rated voltages.
If typical "wet" electros follow the above pattern, then Arfa's
observations would be right on the money.
By comparison, solid electros (as used in current motherboards) appear
to be a *lot* more reliable and according to the datasheet suffer no
degradation in ESR, capacitance or leakage current after being
operated for 7000 hours at rated voltage and temperature (105C).
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
K
Ken G.
Guest
For the past 8 years i have been working on this new stuff ... store
returns ... As time goes on i see more & more samsung products inside
several major branded units . I have seen the same laser pickup used
inside those goofy branded players and inside a supposedly expensive
sony and in those 60$ little foldup portables .
Its all made up of who will send the cheapest part that week . Good luck
returns ... As time goes on i see more & more samsung products inside
several major branded units . I have seen the same laser pickup used
inside those goofy branded players and inside a supposedly expensive
sony and in those 60$ little foldup portables .
Its all made up of who will send the cheapest part that week . Good luck
A
Arfa Daily
Guest
"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:iao4k3pqni7t5kahjhdl8kkgaoplogs4pi@4ax.com...
goes a long way towards explaining what I daily observe. It should also
knock on the head, any and all future discussion as to whether electrolytics
should be rated at +30% of applied voltage, for long-term reliability ...
Thanks for your interesting input on the subject, Franc.
Arfa
news:iao4k3pqni7t5kahjhdl8kkgaoplogs4pi@4ax.com...
That goes along with what Jeff Liebermann said on the subject as well, andOn Mon, 19 Nov 2007 08:50:51 +0000, Eeyore
rabbitsfriendsandrelations@hotmail.com> put finger to keyboard and
composed:
Arfa Daily wrote:
they have tiny 85 deg caps fitted that are rated about 2 volts above
what they
have to work at
There's nothing wrong with that voltage rating. Why do you think they have
a
working voltage rating ?
Graham
I'm aware that solid electros are not relevant to this discussion, but
I found the following datasheet useful because it discusses failure
rates for aluminium electrolytic capacitors:
NSP SERIES - LOW ESR SOLID ALUMINUM ELECTROLYTIC CAPACITOR
http://www.niccomp.com/NSPAppGuide0503.pdf
There is a table at the end which represents a failure rate model as
outlined in MIL-HDBK-217, the Military Handbook for "Reliability
Prediction of Electronic Equipment".
The formula for failure rate (FR) is ...
FR = (BFR) x (temperature factor) x (voltage factor) x (capacitance
value factor)
BFR = Basic Failure Rate for Aluminum Electrolytic Capacitors (per
MIL-HDBK-217F)
FR is influenced by:
- temperature of operation
- applied voltage to voltage rating (voltage ratio factor)
- capacitance value factor
For example, the FR for a 1uF 100V electrolytic capacitor operating at
25C 30V is 1 x BFR.
The same cap operating at its rated voltage would have a 14x greater
failure rate. The voltage factors at voltage ratios of 0.6, 0.7, 0.8
and 0.9 are 2, 3.2, 5.2 and 8.6, respectively. This suggests to me
that any design that allowed for a 50% margin would be 5 times more
reliable than one that operated at rated voltages.
If typical "wet" electros follow the above pattern, then Arfa's
observations would be right on the money.
By comparison, solid electros (as used in current motherboards) appear
to be a *lot* more reliable and according to the datasheet suffer no
degradation in ESR, capacitance or leakage current after being
operated for 7000 hours at rated voltage and temperature (105C).
- Franc Zabkar
--
goes a long way towards explaining what I daily observe. It should also
knock on the head, any and all future discussion as to whether electrolytics
should be rated at +30% of applied voltage, for long-term reliability ...
Thanks for your interesting input on the subject, Franc.
Arfa
M
Michael Kennedy
Guest
"JW" <none@dev.null> wrote in message
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I remember that..On Mon, 19 Nov 2007 18:03:23 GMT "James Sweet" <jamessweet@hotmail.com
wrote in Message id: <Ldk0j.7690$B21.1714@trndny07>:
We've had this conversation before Graham. As a service engineer, which
you, I think, are not, I can only go by experience. The caps which
regularly fail, are (most) always rated just a couple of volts above
what
they are actually running at. Now I know full well that you believe this
to be a nonsense, but I'm sure that anyone else on here who is regularly
involved in actually repairing the stuff, will tell you the same. It
might
be some kind of anomaly in your reckoning, or even not possible to your
mind. That doesn't alter the fact that it is true. It might just be a
physical size versus internal heat issue. I just don't know, but it is
so,
whether you believe it or not.
Other than this, I don't want to get into the discussion, as it's not
what
the thread is about, and the last thing we need is another one
degenerating into a ridiculous flame war, as you get madder and madder,
and all the usual suspects jump in to have a pop at you ...
Second that,
Thirded. I've been repairing electronics equipment for 20+ years.
I haven't seen much from that guy aside from inflamatory flame
posts.
And ditto as well. I was once looking for a source on power cords for some
vintage HP test equipment. The guy pops into the thread ranting and
screaming at me about how different types of wire would not effect the
quality of sound from a stereo system. Sheesh.