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What is the standard for LEDs?

By techrepublic ·
Some of my computers' LEDs are burned out.
What type of LED can be used to replace them?
These are the system is powered on LEDS and the
HARD DRIVE indicator LEDS.

Do they need a resistor inside the LED?
What is the cross over voltage needed?

Thanks for the help.

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by TheChas In reply to What is the standard for ...

First off, are you sure that the LEDs are burnt out, and not just plugged in backwards?

It takes a fairly large voltage spike and current surge to burn out an LED. I would even expect the dropping resistor or driver on the motherboard to fail before the LED itself.

If the LEDs are burnt out, the next question is do you have soldering skills and tools?
While not as demanding a soldering task as working on a motherboard or other computer card, it does take some skill and a reasonable quality soldering station to solder leads to LEDs without damaging the LED.

Next, you need to take the front of the case apart and determine the size of the LEDs and how they are mounted.

If they are soldered to a circuit board, you have a little more flexibility in choosing replacements. If the wires are soldered directly to the LED leads and the LED body snaps into the case, you need to have the exact LED body size and style.

Since you can find new cases without power supplies for under $20 on-line, this might be time to "customize" your system rather than repair it.

As far as the actual LEDs themselves, most case LEDs are basic standard low brightness LEDs with no built-in dropping resistor.

A couple of good sources for raw LEDs are:

www.digikey.com and

For a hit and miss selection of computer case LEDs, take a look at:


They both often have computer case LEDs with leads, or in circuit boards.


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by techrepublic In reply to

Thanks for the feedback.

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by HAL 9000 Moderator In reply to What is the standard for ...

LED's vary in quality depending on who makes them, as far as replacing the dead ones any will do as they should run around the 1.5 VDC though if you use AC Voltage they will flicker at the rate of your number of Hertz per second in the US that's about 60 and in places that use 240 VAC that's about 50. While this shouldn't hurt the LED's they will be flickering but generally speaking way to fast for the naked eye to see.

The other thing that you need to consider is that the Super Bright LED's don't have as wide viewing angle as the lower intensity ones so if you need a wide viewing angle to see the LED's you should use the lower output ones in terms of Candle Power that they produce. Because these are polarised components they should be fitted a certain way to work so the Longer leg in the Cathode + side of the Diode and should go to the coloured wire while the shorted leg goes to the plain wire generally in most cases the white wire and you need to have some Heat Shrink Tubing to cover the exposed metal to prevent shorting out occurring.


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by techrepublic In reply to What is the standard for ...

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