three pin multi colour led to two pin led

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Hello. I've never done this before so I just want to make sure I'm
doing this correctly.  I want to change a three pin multi colour led
activity light on a dvd drive to a two pin blue led. I'm guessing I
need to join the two cathode inputs on the circuit board together?
Makes sense to me but I don't want to screw anything up. Thanks

Re: three pin multi colour led to two pin led
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Look at the circuit diagram or reverse-engineer it.
Tying pins together might work just fine...maybe...or it may let the
smoke out. I can't count the number if times I assumed the designer
was logical and F'd something up.

Depending on how clever the original designer, there's more than one
way to connect stuff.  Tying pins together is a risky thing to do.
Might be safer to replace with two blue led's.
Or, since you're throwing away one indication, use one led and forget the
other.

What's the cost of a new drive?  How badly do you want the blue light?

The thing has two colors for a reason.
I don't remember the Shakespeare quote, but to goes somehthing
like, "if it bothers you, stick tape over it."
Or just Leave it alone and train yourself to ignore it!!!
If you have to ask the question, leaving it alone is appropriate.

Re: three pin multi colour led to two pin led
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    He might also try installing a diode between each input lead and the
controlling lead of the LED.  This would provide isolation and possibly
damage to the other control circuit.

Re: three pin multi colour led to two pin led
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There's a schematic on the board: ----------------------------------
20%
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*--------*--   |
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                                                   |__|__+___________|
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A slightly cruder version(I hope this formats ok) :)  The asterisk
denote contact points.  The top three are what is currently used to
power the three pin led, the other two sets are not being used.

Re: three pin multi colour led to two pin led

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   You need to use a fixed width font, if you want most people to be
able to view your drawing.  Google uses a proportional font as default.


--
You can't fix stupid. You can't even put a Band-Aidô on it, because it's
Teflon coated.

Re: three pin multi colour led to two pin led
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Thanks for the replies.  There's a schematic on the board and it looks
like this.
http://tinypic.com/r/29ynsrq/7Currently the top three
connections are being used for the led.

Re: three pin multi colour led to two pin led
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Your schematic is missing ALL the critical parts.
What drives the leds?
Likely comes out of some chip somewhere and you probably still won't
know what drives the leds unless you reverse-engineer the circuit and/or
the chip, depending on what documentation is available.

Put two blue leds and be done with it.

I am kinda curious what's so important about this that you'd risk
blowing up the drive??

Re: three pin multi colour led to two pin led


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That 'schematic' appears to show two manufacturer's options, the first being
the three pin bi-colour LED that you currently have fitted, and the other
being two single colour LEDs - one in each of the hole pairs below the three
hole set. One thing that you might like to bear in mind is that a blue LED
requires approximately twice the voltage across it to illuminate
satisfactorily, than does a red or green or yellow. This may or may not be
an issue, depending on how the original LEDs are driven. I'm basically with
everyone else. You're asking how to fit triangular wheels to your car, but
nor telling us why exactly you need to do it ...

Arfa


Re: three pin multi colour led to two pin led
On 4/28/2011 2:29 PM tom spake thus:

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IF the 3-pin LED is what's at the top of that schematic, then yes, you
can easily replace it with TWO leds connected as shown. (The three-pin
device is simply two separate LEDs in one package with a common cathode.)

I wouldn't mess with trying to replace this with a single LED. You never
answered the question: why are you doing this?


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The current state of literacy in our advanced civilization:

   yo
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Re: three pin multi colour led to two pin led
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Assuming for discussion the three-pin is a red/green LED, one circuit
powers the red LED while another circuit powers the green LED. Are
these circuits suitable for wired-OR operation? How is the LED current
limited?

Re: three pin multi colour led to two pin led
Use 2 white LEDs and color them blue with a Sharpie or similar translucent
coloring.

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Cheers,
WB
.............


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