Re: We have no green light....

[Graham Cox]

LEDs almost never burn out - unless you stick an AA battery across  
them, that is ;-)

I don't recommend this. Though an LED has a voltage drop of about 1.2V  
(at least red and green ones do), and this is close to an AA battery's  
output, without current limiting it would be very easy to burn out the  
LED even if the battery has only a small amount of excess voltage. You  
MUST have a limiting resistor in there. LED current is usually set at  
about 20 mA, so you can work out what resistor to use from ohms law:

R = (Vbatt - Vled)/0.02

Blue LEDs drop up to 7V depending on type - some drop less. It might  
not be possible to substitute a blue LED, depending on what voltage is  
available on the board, and you would definitely have to change the  
resistor.

--Graham

On 2 Mar 2004, at 8:31 am, Joshua Coombs wrote:

----- Original Message -----
From: "Mark Benson" <[EMAIL PROTECTED]>
To: "Compact Macs" <[EMAIL PROTECTED]>
Sent: Monday, March 01, 2004 2:22 PM
Subject: Re: We have no green light....

Erm. Well....

I replaced the button board and it's not that. Still no LED.
Nothing
seems to have come apart or anything. connector seems to fit on
firmly.
I'm lost.

Might be as simple as a bad/burnt out LED.  Use a AA battery with
some paperclips as test leads, and with the module unplugged, see if
you can get the LED to light by putting power to it directly.  It'll
only work with the polarity in the right direction, so if it fails
to light on your first try, flip the battery around.  If it still
fails to light, you've found your problem.
PC Modders would recomend a nice bright blue replacement LED... : )

Joshua Coombs



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