Change HD & Power leds

[John]

I would like to change the led's in a old pc I recovered amber=power
green=hd from there factory color to different colors like blue and super
red led's.
I use to play electronic hobbies years ago so I’m concerned that if I
just solder the defferent color led’s to the leads I might fry
something.
Any help welcome

 

[John]

On Mon, 02 Feb 2009 14:40:24 +0000, John wrote:

I would like to change the led's in a old pc I recovered amber=power
green=hd from there factory color to different colors like blue and
super red led's.
I use to play electronic hobbies years ago so I’m concerned that if I
just solder the defferent color led’s to the leads I might fry
something.
Any help welcome

Sorry amber is HD and green is power.

 

[John Fields]

On Mon, 02 Feb 2009 14:51:36 GMT, John <johnlostworld-spam@aol.com>
wrote:

On Mon, 02 Feb 2009 14:40:24 +0000, John wrote:

I would like to change the led's in a old pc I recovered amber=power
green=hd from there factory color to different colors like blue and
super red led's.
I use to play electronic hobbies years ago so I’m concerned that if I
just solder the defferent color led’s to the leads I might fry
something.
Any help welcome

Sorry amber is HD and green is power.

---
Measure the supply voltage and get the voltage and current specs for the
new LEDs and then figure out what the values need to be for the new
series resistors, like this:


Vcc - Vled
R = ------------
Iled

Where R is the resistance of the resistor, in ohms,
Vcc is the supply voltage, in volts,
Vled is the LED forward voltage, (from the data sheet) and
Iled is the LED forward current. (from the data sheet.

Then determine how much power the resistors will be dissipating, like
this:


P = (Vcc - Vled) * Iled


where P is the power dissipated, in watts.

A convenient rule-of-thumb to follow is to use a resistor which is rated
to dissipate 2P.

Once you've done all that and you have the parts on hand, carefully
unsolder the old LEDs and resistors and solder in the new ones making
sure you don't get the LED polarities backwards.


JF

 

[Jasen Betts]

On 2009-02-02, John <johnlostworld-spam@aol.com> wrote:

I would like to change the led's in a old pc I recovered amber=power
green=hd from there factory color to different colors like blue and super
red led's.

I use to play electronic hobbies years ago so I’m concerned that if I
just solder the defferent color led’s to the leads I might fry
something.

powersupply for the existing LEDs is most probably 5V through a series
resistor, so just replacing the leds should work. the new leds may not
light to full brightness but will probably look good none-the-less.
There's no risk of damage to the PC by this modification as long as you
take due care.

 

[John Fields]

On 6 Feb 2009 08:47:28 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2009-02-02, John <johnlostworld-spam@aol.com> wrote:
I would like to change the led's in a old pc I recovered amber=power
green=hd from there factory color to different colors like blue and super
red led's.

I use to play electronic hobbies years ago so I’m concerned that if I
just solder the defferent color led’s to the leads I might fry
something.

powersupply for the existing LEDs is most probably 5V through a series
resistor, so just replacing the leds should work. the new leds may not
light to full brightness but will probably look good none-the-less.
There's no risk of damage to the PC by this modification as long as you
take due care.

---
Bad advice.

He needs to _know_ what the supply voltage is and the Vf and If of the
LEDs he wants to use before he can proceed with the modification
intelligently.

JF

 

[John]

On Fri, 06 Feb 2009 07:32:13 -0600, John Fields wrote:

On 6 Feb 2009 08:47:28 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

Thanks for the replys.

 

[Jasen Betts]

On 2009-02-06, John Fields <jfields@austininstruments.com> wrote:

On 6 Feb 2009 08:47:28 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2009-02-02, John <johnlostworld-spam@aol.com> wrote:
I would like to change the led's in a old pc I recovered amber=power
green=hd from there factory color to different colors like blue and super
red led's.

I use to play electronic hobbies years ago so I’m concerned that if I
just solder the defferent color led’s to the leads I might fry
something.

powersupply for the existing LEDs is most probably 5V through a series
resistor, so just replacing the leds should work. the new leds may not
light to full brightness but will probably look good none-the-less.
There's no risk of damage to the PC by this modification as long as you
take due care.

---
Bad advice.

what can go wrong?

He needs to _know_ what the supply voltage is and the Vf and If of the
LEDs he wants to use before he can proceed with the modification
intelligently.

we're talking PC assembly here, intelligence isn't really needed

the motherboard already has resistors for the existing LEDs changing
in higher voltage LEDs isn't going to damage anything.

 

On Feb 6, 9:32 am, John Fields <jfie...@austininstruments.com> wrote:

On 6 Feb 2009 08:47:28 GMT, Jasen Betts <ja...@xnet.co.nz> wrote:

On 2009-02-02, John <johnlostworld-s...@aol.com> wrote:
I would like to change the led's in a old pc I recovered amber=power
green=hd from there factory color to different colors like blue and super
red led's.

I use to play electronic hobbies years ago so I’m concerned that if I
just solder  the defferent color led’s to the leads  I might fry
something.

powersupply for the existing LEDs is most probably 5V through a series
resistor, so just replacing the leds should work.  the new leds may not
light to full brightness but will probably look good none-the-less.
There's no risk of damage to the PC by this modification as long as you
take due care.

---
Bad advice.

He needs to _know_ what the supply voltage is and the Vf and If of the
LEDs he wants to use before he can proceed with the modification
intelligently.

JF  

Actually it was good advice. They are current limited already, within
the typical sub-20mA range as with any other 100mW encapsulated LED.
This is a necessary design parameter for motherboards. You can blindly
grab a similar looking LED and hook it up to any motherboard without
issue, and indeed that is exactly what happens when you install your
choice of motherboard into a computer case.

The intelligent data collection choice is significant if a mistake
would take a great deal of time or expense if things went wrong, which
it won't, or if there was nothing yet known about motherboard
circuitry, which there is.