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Replacing the power LED...


liquidcross

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Anyone ever done it? I want to put in a green or blue one...

 

Yep, and it's easy enough to do. The polarity is marked on the board (the silkscreened line is the cathode or negative leg - usually longer on a new LED), if you're not already au fait with doing this :)

 

My own Jag has a switchable bi-colour (red/green) LED in there, so I can make it look like an NTSC or PAL one with the flick of a switch (if you didn't already know, PAL Jags have green power LEDs, and NTSC have red). I've also converted 2 Jags (one to a Stub dev Jag, one to a BJL Jag) with a power LED that reflects the state of the region-switch I installed - 50Hz makes the LED green, and 60Hz makes it red. A very cool effect, though I like my switchable one more :D

 

I always thought orange would look nice...then again I saw a multi-coloured flashing one for sale at one stage I thought could be good...but now I'm rambling :)

 

The answer to your question is yes, it can be done, and easily, just get the polarity right and all should be fine. Note: the Jag factory bent the LED legs outwards at extreme angles to hold it in the board before soldering and snipping the legs off - make sure you remove *all* the solder from the legs and then use some needle-nose pliers to get the LED off the board. I've had severe difficulties in the past, just thought I'd share :)

 

Rgs,

 

Stone

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AFAIK, all LEDs drop 2V...

 

I guess the 3.7V one has an internal resistor or something...

 

The Jag power LED runs off 5V through a 330R resistor, iirc, which makes the current flow 15mA (I= V/R = 5/330 = 0.015A = 15mA) - any standard LED should work. You should use a 5mm type to be the same size as the one in the Jag already, btw.

 

I'm still confused about voltage ratings...I never knew LEDs had them! I've been taught that all LEDs drop 2V, with the protective resistor being required in order to take the other 3V and prevent the power supply from being forced into an intermediate state with the weaker of the two components giving way (in this case the LED).

 

Just straight replacement of the LED with a 'normal' 5mm type should work fine.

 

Stone

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FYI, an LED only drops .7V - just like any other diode. Who taught you it was 2V drop. Put a meter across one when it's powered up - the LED itself, not the current limiting resistor. I suggest a 5V diode, but blue LEDs are only available in 3.3V. After you've installed it, if its too bright, install a higher value current limiter. Likewise, if it's too dim - nix it altogether.

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Do what I suggested via PM earlier, check the actual voltage.

I shall. For that "zero ohm" resistor...I can just use a piece of jumper wire instead, yes?

 

My advice would be not to mess with the resistor at all...it's only 330R and can easily cope with taking a tiny bit extra voltage with a 3.3V LED (whatever the hell they are). The protective resistor is only there to limit the amount of CURRENT going into the LED - as it's a junction drop, it'll take whatever voltage it needs and leave the rest of the 5V across the resistor. Simple. Kinda...;)

 

Leave the resistor alone and replace the LED - I'd be 95% certain it's not gonna die. If you replace the resistor with a zero-ohm one and the LED doesn't contain its own current-limiting resistor then it can draw near-infinite current from the power supply, which WILL blow it. Not worth the risk, IMO.

 

Stone

 

Stone

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My advice would be not to mess with the resistor at all...it's only 330R and can easily cope with taking a tiny bit extra voltage with a 3.3V LED (whatever the hell they are). The protective resistor is only there to limit the amount of CURRENT going into the LED - as it's a junction drop, it'll take whatever voltage it needs and leave the rest of the 5V across the resistor. Simple. Kinda...;)

 

Leave the resistor alone and replace the LED - I'd be 95% certain it's not gonna die. If you replace the resistor with a zero-ohm one and the LED doesn't contain its own current-limiting resistor then it can draw near-infinite current from the power supply, which WILL blow it. Not worth the risk, IMO.

 

Stone

 

Stone

Cool. I'll just nab another 3.7V blue LED, and try that.

 

Out of curiosity...what's the "R" notation you used for the resistor? i.e., "330R". Do you mean 330 ohm?

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Cool. I'll just nab another 3.7V blue LED, and try that.

 

Good :) Let us all know what happens.

 

Out of curiosity...what's the "R" notation you used for the resistor? i.e., "330R". Do you mean 330 ohm?

 

Yes. It's part of the engineering resistor notation - while 1,000,000 ohms is written 1M, and 2700 ohms 2K7, it's sensible to have another symbol meaning 'units' rather than having people potentially confused over the numbers. The idea is to remove the decimal point, so it's possible to print it in really small letters on components...and just to insulate engineers from the world a little more :) Sorry if I caused confusion ;)

 

Stone

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It's part of the engineering resistor notation - while 1,000,000 ohms is written 1M, and 2700 ohms 2K7, it's sensible to have another symbol meaning 'units' rather than having people potentially confused over the numbers. The idea is to remove the decimal point, so it's possible to print it in really small letters on components...and just to insulate engineers from the world a little more :) Sorry if I caused confusion ;)

 

Stone

No problem. I'm just used to writing 1M ohm, 2.7k ohm, etc. :D

 

Anyways, I'll get the work done sometime next week. My friend's sending me a Jaguar deck, so I'll have to track down some accessories for it after I return from my vacation this weekend.

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Yeah, don't mess with the resistor unless you find the LED to be too dim. And then try going with a smaller value before going with the zero ohm (or jumper). Some LEDs have the current limiter built-in - some don't. I think 3.7V is the standard (not 3.3V). Also, after checking out the 5V versions, they require a minimum of 4.4V to light properly.

 

You can check this place for LEDs:

http://ledmuseum.home.att.net

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Yeah, the $5.00 handling fee pisses me off too.  :x

 

$5??? You got off lightly. I ordered some stuff off them ages ago and got one of their new catalogues a little while ago...I believe it was a £15 handling fee on orders under £75, and a flat-rate shipping fee of £20. Needless to say, the catalogue went straight in the bin after seeing that bit...:roll:

 

Stone

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