Case LED

[Travis King]

One of the LEDs of the "headlight" of my Apevia X-Infinity is starting to
burn out as it is much dimmer now and it's flickering. I've been looking
around on the Internet for information about LEDs, but I'm not finding a
lot. Would it be possible to replace the blue LED without replacing the
whole case and if so, how? Thanks.

 

[Paul]

One of the LEDs of the "headlight" of my Apevia X-Infinity is starting
to burn out as it is much dimmer now and it's flickering. I've been
looking around on the Internet for information about LEDs, but I'm not
finding a lot. Would it be possible to replace the blue LED without
replacing the whole case and if so, how? Thanks.

The LED might be soldered to a small piece of PCB. But
before I replaced one, I'd want to check to see what
conditions the manufacturer was applying to it. That
is not the first time I've heard of some super-bright
case LEDs burning out.

It could also be a bad connection. A cold solder joint,
cracked PCB, heat-damaged current limiting resistor and
so on. You'd need to pull the module and have a look.

A LED circuit consists of:

1) power source
2) current limiting resistor
3) the LED

The higher the resistance value, the weaker the LED output. The
LED has a maximum current it can take, listed in the datasheet.
LEDs are now available that can take 1 ampere of current (and
years ago, I had in my possession, a LED that took 2 amps, but
you cannot buy those any more). But devices taking that much
current, need a heatsink attached to them. Ordinary LEDs might
use anywhere from 10 milliamps to 50 milliamps or so. Some
examples here - the second link is a page from the Digikey catalog.
You can see in the catalog page, that 3.5V to 4V of forward
bias has to be applied, before you get any blue light. So either
the 5V or the 12V rail of your PSU would be needed to power a
blue LED circuit, and the 5V is a bit safer. LEDs have a maximum
reverse voltage you can apply, and typical dime-store LEDs are
good for 5V in reverse (which is why hardly anyone ruins the LEDs
on their computer case, by reversing the two pin cable).

http://rocky.digikey.com/WebLib/Lit...L2T3TBK3,LTL2T3TBK4,LTL2T3TBK5,LTL2P3TBK5.jpg
http://dkc3.digikey.com/PDF/T072/P2192.pdf

More trivia here, including polarity determination (so you can
figure out which is the plus and minus lead). The most reliable
info can be obtained from the device datasheet, if you can track
one down.

http://en.wikipedia.org/wiki/Led

Have fun,
Paul

 

[kony]

Ordinary LEDs might
use anywhere from 10 milliamps to 50 milliamps or so.

Generally speaking, the typical case LEDs can be driven at
up to 30mA, with good heatsinking via leads that are short
and soldered to a large copper plane. Even so, it should
have still lasted longer than this unless the case is fairly
old and continuously powered. A more conservative estimate
for a typical superbright LED is 20mA. However if there
are more than one LED creating some visual effect, it might
require driving the LED to the same brightness level as the
others so it *matches* the others' output instead of being
brighter or dimmer, which would hopefully be accomplished by
the drop-in replacement LED, but not necessarily.

Some
examples here - the second link is a page from the Digikey catalog.
You can see in the catalog page, that 3.5V to 4V of forward
bias has to be applied, before you get any blue light.

That seems pretty high, often the forward drop is closer to
about 3.2 - 3.6V. Often the resistor used is 470 Ohm on 12V
rail or 68-120 Ohm if powered by 5V rail.


To the OP - Take out the LED and describe the circuit
*around* it. Probably a resistor going to a molex 4-pin
plug? If so, follow the circuit board traces if on a board,
and tell us the color stripes on the LED. However, "odds"
are that if you picked a typical general ultrabright blue
LED, it would be a drop in replacement.

This is unless the problem is not the LED, it might be
damaged wiring. In particular on some cases the wiring is
so high gauge (fragile) that the wire breaks off, typically
right at the point where it is soldered to the LED.

Do you have a soldering iron? It would certainly make the
repair more reliable. To start out with a plan to replace
it, it would help us to know what skills and related tools
you have as it's not necessarily likely you can just buy an
exact replacement - though you might try contacting Aspire
as you never know, they might rise to the occasion and send
you the assembly.

Do you *require* blue? You could (within some limits, red
would probably require changing the resistor as it has a
lower forward voltage drop than most) pick a different color
like purple or aqua. Here's one place that has a blue and
unlike Digikey and many electronics houses, might just drop
it in a first class envelop for minimal shipping cost if you
asked them nicely (they used to do this, YMMV if they still
will), but otherwise it'll be a crazy overhead practically
anywhere to pay $6+ for shipping a < $1 LED.
http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=11757

In that case it could end up cheaper to just take the LED
out of something like this,
http://www.svc.com/lzled3blu.html
and I link SVC specifically because they will ship small
items at a USPS, First Class Mail rate is about $3 in the
US. There might be other even cheaper blue LEDs on SVC's
site, I didn't look for very long.

 

[kony]

If so, follow the circuit board traces if on a board,
and tell us the color stripes on the LED.

.... stripes on the resistor, not LED.

 

[Travis King]

Generally speaking, the typical case LEDs can be driven at
up to 30mA, with good heatsinking via leads that are short
and soldered to a large copper plane. Even so, it should
have still lasted longer than this unless the case is fairly
old and continuously powered. A more conservative estimate
for a typical superbright LED is 20mA. However if there
are more than one LED creating some visual effect, it might
require driving the LED to the same brightness level as the
others so it *matches* the others' output instead of being
brighter or dimmer, which would hopefully be accomplished by
the drop-in replacement LED, but not necessarily.


That seems pretty high, often the forward drop is closer to
about 3.2 - 3.6V. Often the resistor used is 470 Ohm on 12V
rail or 68-120 Ohm if powered by 5V rail.


To the OP - Take out the LED and describe the circuit
*around* it. Probably a resistor going to a molex 4-pin
plug? If so, follow the circuit board traces if on a board,
and tell us the color stripes on the LED. However, "odds"
are that if you picked a typical general ultrabright blue
LED, it would be a drop in replacement.

This is unless the problem is not the LED, it might be
damaged wiring. In particular on some cases the wiring is
so high gauge (fragile) that the wire breaks off, typically
right at the point where it is soldered to the LED.

Do you have a soldering iron? It would certainly make the
repair more reliable. To start out with a plan to replace
it, it would help us to know what skills and related tools
you have as it's not necessarily likely you can just buy an
exact replacement - though you might try contacting Aspire
as you never know, they might rise to the occasion and send
you the assembly.

Do you *require* blue? You could (within some limits, red
would probably require changing the resistor as it has a
lower forward voltage drop than most) pick a different color
like purple or aqua. Here's one place that has a blue and
unlike Digikey and many electronics houses, might just drop
it in a first class envelop for minimal shipping cost if you
asked them nicely (they used to do this, YMMV if they still
will), but otherwise it'll be a crazy overhead practically
anywhere to pay $6+ for shipping a < $1 LED.
http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=11757

In that case it could end up cheaper to just take the LED
out of something like this,
http://www.svc.com/lzled3blu.html
and I link SVC specifically because they will ship small
items at a USPS, First Class Mail rate is about $3 in the
US. There might be other even cheaper blue LEDs on SVC's
site, I didn't look for very long.

Here's a picture of the case. It's brighter in the picture than it is in
person, but I think you can easily tell which one it is.
http://img108.imageshack.us/img108/325/img3033bt2.jpg

The case is two years old, and it is almost continuously on. I will have to
look to make sure, but I believe all the blue LEDs are connected together,
and then there's a place to plug in a y-splitter where you plug your 4-pin
molex connector into. Then there's another one for the digital temperature
monitor.\

I would rather stay with a blue LED or else I'd have to change all of my
LEDs in my case to a different color. My case fans, digital temperature
display, and all the LEDs that light up the "X-Infinity" thing and the
headlights are blue. The case looks almost like a BMW towards the top, and
each headlight consists of two LEDs.

I have a soldering iron, and I know how to get to the front panel and remove
the LEDs. I am up for alternatives besides replacing the LEDs such as
putting different kinds of lights in there that might produce the same
effect.

 

[kony]

Here's a picture of the case. It's brighter in the picture than it is in
person, but I think you can easily tell which one it is.
http://img108.imageshack.us/img108/325/img3033bt2.jpg

Since this is one LED out of 4, you might find the
replacement doesn't quite match in hue or intensity. If
having it match is important, I would buy at least 4 of the
same replacement LED then after having replaced the one, if
it doesn't match then replace the others as well.

The case is two years old, and it is almost continuously on. I will have to
look to make sure, but I believe all the blue LEDs are connected together,
and then there's a place to plug in a y-splitter where you plug your 4-pin
molex connector into. Then there's another one for the digital temperature
monitor.\

Two years is nothing for an LED, it should last many years
longer unless they had overdriven it (too much current) to
produce more light and/or use a lower grade (cheaper) LED
for the same amount of light. It might just be flawed, but
if they had overdriven it, if you find it later fails again,
you might use a slightly large value of resistor than they
did (and accept the associated decrease in brightness,
except that if you chose an LED with a higher MCD value then
it might still be more or less bright regardless of a little
lower current). Then again while it looks like an LED
failure it might be wiring, I'd take it apart and examine it
before ordering anything.

There's lots more to picking LEDs but it might be overkill
to mention things like viewing angle as it's likely a
typical (most common) 30' or less type, not wide-beam.

I would rather stay with a blue LED or else I'd have to change all of my
LEDs in my case to a different color. My case fans, digital temperature
display, and all the LEDs that light up the "X-Infinity" thing and the
headlights are blue. The case looks almost like a BMW towards the top, and
each headlight consists of two LEDs.

I have a soldering iron, and I know how to get to the front panel and remove
the LEDs. I am up for alternatives besides replacing the LEDs such as
putting different kinds of lights in there that might produce the same
effect.

LEDs are the best bet. Mounting anything else could be
fiddly and would (normally, ignoring this odd failure you
have) be shorter lived and potentially produce more heat and
would make it harder to achieve the same color, brightness
level, and semi-focused output without a lens and a current
control method.

 

[Travis King]

Since this is one LED out of 4, you might find the
replacement doesn't quite match in hue or intensity. If
having it match is important, I would buy at least 4 of the
same replacement LED then after having replaced the one, if
it doesn't match then replace the others as well.




Two years is nothing for an LED, it should last many years
longer unless they had overdriven it (too much current) to
produce more light and/or use a lower grade (cheaper) LED
for the same amount of light. It might just be flawed, but
if they had overdriven it, if you find it later fails again,
you might use a slightly large value of resistor than they
did (and accept the associated decrease in brightness,
except that if you chose an LED with a higher MCD value then
it might still be more or less bright regardless of a little
lower current). Then again while it looks like an LED
failure it might be wiring, I'd take it apart and examine it
before ordering anything.

There's lots more to picking LEDs but it might be overkill
to mention things like viewing angle as it's likely a
typical (most common) 30' or less type, not wide-beam.





LEDs are the best bet. Mounting anything else could be
fiddly and would (normally, ignoring this odd failure you
have) be shorter lived and potentially produce more heat and
would make it harder to achieve the same color, brightness
level, and semi-focused output without a lens and a current
control method.

I contacted the company a few days ago, and I just got a response today that
they will offer me a $6 replacement string of LEDs. I will have to replace
all the LEDs, but this will be easier than trying to find one that works
Before I officially order a replacement, I'm going to make sure there's not
a bad connection like you said. Thanks.

 

[Travis King]

I contacted the company a few days ago, and I just got a response today
that they will offer me a $6 replacement string of LEDs. I will have to
replace all the LEDs, but this will be easier than trying to find one that
works Before I officially order a replacement, I'm going to make sure
there's not a bad connection like you said. Thanks.

Checked the wiring. Looked good. Even took the front panel off to look at
the wiring going to the LEDs. That looked fine also. Turned on the
computer, and now that LED is completely dead. On occasion, I'll see just
the faintest blue, but otherwise, it's dead.

 

[kony]

Checked the wiring. Looked good. Even took the front panel off to look at
the wiring going to the LEDs. That looked fine also. Turned on the
computer, and now that LED is completely dead. On occasion, I'll see just
the faintest blue, but otherwise, it's dead.

If an LED fails through only moderate overcurrent/heat, it
may tend to still (barely) dimly glow. It is unusual to
have it flicker though, that was one of the reasons I
wondered about the wiring. If/when it breaks it tends to do
so right at where the wire is soldered to the LED lead
(unless there was some overt accident like it getting caught
in a fan) and if that is covered in heatshrink tubing it may
not be obvious with a visual inspection. Wiggling the wire
around can sometimes find this fault or checking continuity
between the other end of the wire and the LED lead itself
(easiest to take a multimeter needle probe which pierces a
small enough hole that it's essentially self-closing after
the needle is withdrawn.

$6 seems very reasonable to replace the whole set (assuming
they don't gouge you on S/H charges), now just hope the
replacement isn't subject to same failure within the life of
the system. At least with the replacement set you
"hopefully" have all same LEDs and if one fails in the
future you have spares. If another fails I suggest doing
what I'd mentioned previously, to examine the connector and
determine what resistor value they are using and replace
that with a somewhat higher value, or add this resistor in
series with the positive power lead while leaving the
original in place, which of course means choosing a much
lower value of resistor. As mentioned in one of my past
posts, 20mA (0.02A in equation below) or a little less is a
typical conservative current to allow, then depending on
whether the LEDs are in parallel or series themselves you
can Google for an LED resistor calculator which will
elaborate on the basic theme of;

[ (PSU voltage supplied by connector, 5 or 12V) - [ (# of
LEDs in series) * (Forward Voltage Drop per LED) ] ] /
0.02A = n Ohms resistor per group of LEDs

Per group of LEDs means it might be one resistor for the
whole thing, one per LED, or one per pair of LEDs. Noting
the value of the original resistor(s) is a good start.

 

[Travis King]

Checked the wiring. Looked good. Even took the front panel off to look
at
the wiring going to the LEDs. That looked fine also. Turned on the
computer, and now that LED is completely dead. On occasion, I'll see just
the faintest blue, but otherwise, it's dead.

If an LED fails through only moderate overcurrent/heat, it
may tend to still (barely) dimly glow. It is unusual to
have it flicker though, that was one of the reasons I
wondered about the wiring. If/when it breaks it tends to do
so right at where the wire is soldered to the LED lead
(unless there was some overt accident like it getting caught
in a fan) and if that is covered in heatshrink tubing it may
not be obvious with a visual inspection. Wiggling the wire
around can sometimes find this fault or checking continuity
between the other end of the wire and the LED lead itself
(easiest to take a multimeter needle probe which pierces a
small enough hole that it's essentially self-closing after
the needle is withdrawn.

$6 seems very reasonable to replace the whole set (assuming
they don't gouge you on S/H charges), now just hope the
replacement isn't subject to same failure within the life of
the system. At least with the replacement set you
"hopefully" have all same LEDs and if one fails in the
future you have spares. If another fails I suggest doing
what I'd mentioned previously, to examine the connector and
determine what resistor value they are using and replace
that with a somewhat higher value, or add this resistor in
series with the positive power lead while leaving the
original in place, which of course means choosing a much
lower value of resistor. As mentioned in one of my past
posts, 20mA (0.02A in equation below) or a little less is a
typical conservative current to allow, then depending on
whether the LEDs are in parallel or series themselves you
can Google for an LED resistor calculator which will
elaborate on the basic theme of;

[ (PSU voltage supplied by connector, 5 or 12V) - [ (# of
LEDs in series) * (Forward Voltage Drop per LED) ] ] /
0.02A = n Ohms resistor per group of LEDs

Per group of LEDs means it might be one resistor for the
whole thing, one per LED, or one per pair of LEDs. Noting
the value of the original resistor(s) is a good start.

Apevia said that the $6 includes the shipping charge.

 

[~misfit~]

"Travis King" <[email protected]> wrote in message

I contacted the company a few days ago, and I just got a
response today that they will offer me a $6 replacement string
of LEDs. I will have to replace all the LEDs, but this will be
easier than trying to find one that
works Before I officially order a replacement, I'm going to
make sure there's not a bad connection like you said. Thanks.

Checked the wiring. Looked good. Even took the front panel off
to look at
the wiring going to the LEDs. That looked fine also. Turned on
the computer, and now that LED is completely dead. On occasion,
I'll see just the faintest blue, but otherwise, it's dead.

If an LED fails through only moderate overcurrent/heat, it
may tend to still (barely) dimly glow. It is unusual to
have it flicker though, that was one of the reasons I
wondered about the wiring. If/when it breaks it tends to do
so right at where the wire is soldered to the LED lead
(unless there was some overt accident like it getting caught
in a fan) and if that is covered in heatshrink tubing it may
not be obvious with a visual inspection. Wiggling the wire
around can sometimes find this fault or checking continuity
between the other end of the wire and the LED lead itself
(easiest to take a multimeter needle probe which pierces a
small enough hole that it's essentially self-closing after
the needle is withdrawn.

$6 seems very reasonable to replace the whole set (assuming
they don't gouge you on S/H charges), now just hope the
replacement isn't subject to same failure within the life of
the system. At least with the replacement set you
"hopefully" have all same LEDs and if one fails in the
future you have spares. If another fails I suggest doing
what I'd mentioned previously, to examine the connector and
determine what resistor value they are using and replace
that with a somewhat higher value, or add this resistor in
series with the positive power lead while leaving the
original in place, which of course means choosing a much
lower value of resistor. As mentioned in one of my past
posts, 20mA (0.02A in equation below) or a little less is a
typical conservative current to allow, then depending on
whether the LEDs are in parallel or series themselves you
can Google for an LED resistor calculator which will
elaborate on the basic theme of;

[ (PSU voltage supplied by connector, 5 or 12V) - [ (# of
LEDs in series) * (Forward Voltage Drop per LED) ] ] /
0.02A = n Ohms resistor per group of LEDs

Per group of LEDs means it might be one resistor for the
whole thing, one per LED, or one per pair of LEDs. Noting
the value of the original resistor(s) is a good start.

Apevia said that the $6 includes the shipping charge.

Get two.

 

[Travis King]

On Thu, 07 Jun 2007 03:06:11 GMT, "Travis King"


I contacted the company a few days ago, and I just got a
response today that they will offer me a $6 replacement string
of LEDs. I will have to replace all the LEDs, but this will be
easier than trying to find one that
works Before I officially order a replacement, I'm going to
make sure there's not a bad connection like you said. Thanks.

Checked the wiring. Looked good. Even took the front panel off
to look at
the wiring going to the LEDs. That looked fine also. Turned on
the computer, and now that LED is completely dead. On occasion,
I'll see just the faintest blue, but otherwise, it's dead.


If an LED fails through only moderate overcurrent/heat, it
may tend to still (barely) dimly glow. It is unusual to
have it flicker though, that was one of the reasons I
wondered about the wiring. If/when it breaks it tends to do
so right at where the wire is soldered to the LED lead
(unless there was some overt accident like it getting caught
in a fan) and if that is covered in heatshrink tubing it may
not be obvious with a visual inspection. Wiggling the wire
around can sometimes find this fault or checking continuity
between the other end of the wire and the LED lead itself
(easiest to take a multimeter needle probe which pierces a
small enough hole that it's essentially self-closing after
the needle is withdrawn.

$6 seems very reasonable to replace the whole set (assuming
they don't gouge you on S/H charges), now just hope the
replacement isn't subject to same failure within the life of
the system. At least with the replacement set you
"hopefully" have all same LEDs and if one fails in the
future you have spares. If another fails I suggest doing
what I'd mentioned previously, to examine the connector and
determine what resistor value they are using and replace
that with a somewhat higher value, or add this resistor in
series with the positive power lead while leaving the
original in place, which of course means choosing a much
lower value of resistor. As mentioned in one of my past
posts, 20mA (0.02A in equation below) or a little less is a
typical conservative current to allow, then depending on
whether the LEDs are in parallel or series themselves you
can Google for an LED resistor calculator which will
elaborate on the basic theme of;

[ (PSU voltage supplied by connector, 5 or 12V) - [ (# of
LEDs in series) * (Forward Voltage Drop per LED) ] ] /
0.02A = n Ohms resistor per group of LEDs

Per group of LEDs means it might be one resistor for the
whole thing, one per LED, or one per pair of LEDs. Noting
the value of the original resistor(s) is a good start.

Apevia said that the $6 includes the shipping charge.

Get two.

The LEDs will come with both sides, so that would essentially be two. I'll
only need to replace one side. There are four LEDs on each side of the
case, and each set of four LEDs are connected to one wire that plugs into
the 4-pin molex. This means there will be two seperate strings of LEDs.

 

[~misfit~]

On Thu, 07 Jun 2007 03:06:11 GMT, "Travis King"


I contacted the company a few days ago, and I just got a
response today that they will offer me a $6 replacement
string of LEDs. I will have to replace all the LEDs, but
this will be easier than trying to find one that
works Before I officially order a replacement, I'm going to
make sure there's not a bad connection like you said. Thanks.

Checked the wiring. Looked good. Even took the front panel
off to look at
the wiring going to the LEDs. That looked fine also. Turned
on the computer, and now that LED is completely dead. On
occasion, I'll see just the faintest blue, but otherwise,
it's dead.


If an LED fails through only moderate overcurrent/heat, it
may tend to still (barely) dimly glow. It is unusual to
have it flicker though, that was one of the reasons I
wondered about the wiring. If/when it breaks it tends to do
so right at where the wire is soldered to the LED lead
(unless there was some overt accident like it getting caught
in a fan) and if that is covered in heatshrink tubing it may
not be obvious with a visual inspection. Wiggling the wire
around can sometimes find this fault or checking continuity
between the other end of the wire and the LED lead itself
(easiest to take a multimeter needle probe which pierces a
small enough hole that it's essentially self-closing after
the needle is withdrawn.

$6 seems very reasonable to replace the whole set (assuming
they don't gouge you on S/H charges), now just hope the
replacement isn't subject to same failure within the life of
the system. At least with the replacement set you
"hopefully" have all same LEDs and if one fails in the
future you have spares. If another fails I suggest doing
what I'd mentioned previously, to examine the connector and
determine what resistor value they are using and replace
that with a somewhat higher value, or add this resistor in
series with the positive power lead while leaving the
original in place, which of course means choosing a much
lower value of resistor. As mentioned in one of my past
posts, 20mA (0.02A in equation below) or a little less is a
typical conservative current to allow, then depending on
whether the LEDs are in parallel or series themselves you
can Google for an LED resistor calculator which will
elaborate on the basic theme of;

[ (PSU voltage supplied by connector, 5 or 12V) - [ (# of
LEDs in series) * (Forward Voltage Drop per LED) ] ] /
0.02A = n Ohms resistor per group of LEDs

Per group of LEDs means it might be one resistor for the
whole thing, one per LED, or one per pair of LEDs. Noting
the value of the original resistor(s) is a good start.

Apevia said that the $6 includes the shipping charge.

Get two.

The LEDs will come with both sides, so that would essentially be two.
I'll only need to replace one side. There are four LEDs on each side
of the case, and each set of four LEDs are connected to one wire that
plugs into the 4-pin molex. This means there will be two seperate
strings of LEDs.

Yeah yeah, I got all that.

I meant, get two lots. At that price, and with a history of failure, it
might be a good idea.

 

[kony]

Yeah yeah, I got all that.

I meant, get two lots. At that price, and with a history of failure, it
might be a good idea.

$6 delivered is a great price for the set, but I'd still
think about adding a series resistor either way, or swapping
out the original, as 4+ ultrabright LEDs is a lot of light
which might look cool initially but you get used to the
effect.

 

[Travis King]

$6 delivered is a great price for the set, but I'd still
think about adding a series resistor either way, or swapping
out the original, as 4+ ultrabright LEDs is a lot of light
which might look cool initially but you get used to the
effect.

Keep in mind that this case is in a bedroom, so having something that is
much brighter than it is now would not work out well. The case is already
close to being too bright for a bedroom. It already lights up the room more
than a nightlight would.

 

[kony]

Keep in mind that this case is in a bedroom, so having something that is
much brighter than it is now would not work out well. The case is already
close to being too bright for a bedroom. It already lights up the room more
than a nightlight would.

No, swapping in the resistor lowers the current (for longer
LED life) which would lower the brightness a bit. That is,
so long as you increase the series resistance to the LEDs
which lowers the current.