Hardware noob, changing DVD-RW drive LED light.

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solidsnake204

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Mar 19, 2010
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I have a Samsung SH-S223 SATA DVD-RW drive.

However, as a little sort of project, I would like to change the green LED for a blue LED (To match the case) and also very slightly enlarge the hole for the LED light (Just using a drill to do this, easy enough).

I understand how to do it (At least I think I do...): Unsolder the LED, remove it from the plastic holder, insert new LED into holder, solder LED, done.

I myself wont be doing the soldering (For a start I don't even own a soldering iron), so I'll let my friend do the soldering part.

But my questions are about the LED itself. I measured the width across the LED and it was 5mm. However, 5mm LED's come in 5v and 12v varieties, would it be safe to assume that the drive LED would be a 5v?

As for the LED, would this LED work? (And which one should I get, diffused or clear?)
http://maplin.co.uk/Module.aspx?ModuleNo=12703

Thanks in advance.
 
I'd get diffused, and yes it should be a 5v LED, though you can test that with a cheap multimeter (plug in the drive, set the multimeter to DC, touch both legs of the LED and see what voltage it reads).
 
Blue LEDs have a typical Vf of about 3.5-4V; non ultrabright ones are more around 2V, but almost everything is the ultrabright type these days. There are definitely not any common 12V 5mm blue LEDs - if they're sold as such, they have an integrated resistor or are bundled with resistors - you don't want this since the resistor will be on the DVD board. In fact the voltage doesn't really matter as long as your supply voltage is higher than the Vf of the LED, it's the current that you must regulate. However the DVD drive will already have current limiting, the only concern is that it might be a 3.3V logic line driving the LED, which may not be high enough to turn on a blue LED which have significantly higher Vf than the standard green or red. If you have a multimeter, you should remove the existing LED and then measure the voltage across the pins and confirm it's higher than the specified Vf of your LED or it won't work. 3.2V blue LEDs are available, but they're somewhat less common, and if you do only have a 3.3V output you probably will also need to change the current limit resistor on the board (which you might need to do with a blue LED anyway since Vf is so much higher, but it's worth a test to see if it's bright enough for you). With a 3.2 or 3.3V LED and a 3.3V logic output you might get away without current limiting so you could just jumper across the resistor, but you might not...

If there's a light pipe that the LED touches to bring the indicator out to the front, go with the clear LED. Otherwise go with the diffused one. Those LEDs will work, but wow that price is awful.

Is the old LED not a square type? Most CD/DVD drives I've taken apart use square ones mounted directly in the faceplate.
 
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Vf is a property of the device. It can vary fairly widely depending on how it's constructed; you'll need to look at datasheets for the particular LEDs. White tend to have about the same Vf as blue since they're constructed very similarly from the same materials. About 3.2-4V. ~2V blue LEDs are available, but they'll be tougher to find and dimmer, but probably fine for an indicator.

TL;DR of the below wordiness:

If you're going to use an LED with Vf above 3.3V or so, verify that the voltage applied on the board to the LED when it's removed is at least a few tenths of a volt higher than the specified Vf. If it's not you need to find an LED with a lower Vf. After installation if the LED is too dim for your preference, find and replace the LED resistor.

You may want to just find a 2V blue LED, it will make this a simple swap and you won't have to worry about any of this :p

And if I the VF isn't high enough on the DVD board, would I just remove the current resistor and solder in a new one?
Click to expand...
Vf is the voltage the LED needs to have applied to it before it will turn on. Below that voltage very little current (basically none) will flow through the LED and it will be off or extremely dim. Once you reach that voltage it will come on abruptly. But once on, unless the voltage is very close to the actual LED voltage, current ramps up extremely fast - if you drive the LED with just a couple 10ths of a volt too much it will have much too current through it and will burn up. So you place a resistor there as a current limiter, basically it 'burns' any additional voltage that is above the LED's Vf and sets the current (remember V=IR from high school physics, V is fixed by the supply voltage and LED Vf, R is also fixed, so current is fixed as well. Consequently if you increase Vf, the extra voltage across the LED means less voltage on the resistor, so current falls as well, which is why you might need to change the resistor). When you remove the LED from the circuit, the voltage at the resistor is the maximum the DVD drive can output; if it's not high enough, you need an LED with a lower Vf or a more complicated circuit to drive the LED. However if the voltage is high enough but you hook it up and find it's quite dim, removing and replacing the resistor with a lower valued one will allow more current and make the LED brighter.
 
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Sorry, I don't even know of a place in North America or a part number from a reliable manufacturer. However, Futurlec claims to sell some and I've been happy with purchases from them before, but not these LEDs (though they take forever to ship): http://futurlec.com/LED/LED5B.shtml .
 
Have you taken the drive apart yet and checked the led? I have done this mod on several drives and they have always been 3mm leds. If it is a 5mm, I'd be surprised.

That being said figure on a 3.3v 20mA LED these are pretty common.

You can pick them up at most electronic stores, Maplin is the only one I knoe of in UK, in the US, Mouser, Digikey, Radioshack, Sidewinder PC, Frozen Cpu, FRY's, etc. Pretty much any good electronic/pc parts/modding vendor.

But here is a Mapin link to a blue 3.3 v (3.3-3.6Vf) Blue LED.

5mm

3mm

Edit: as far as diffusing the led you can do it with a little bit of high count sandpaper 800grit etc.
 
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