change x0xb0x-LEDs

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roxxx303
 
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Joined: Tue Nov 08, 2011 11:33 am

change x0xb0x-LEDs

Post by roxxx303 »

Hi,

I want to change the red LEDs to blue ones. I have a pre-build x0xb0x and I am no electronic-expert.
Can I use these ? :

http://de.opitec.com/opitec-web/article ... VkIGJsYXUz

If not which must I use?
Is it difficult to change ?

Thanks!

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antto
 
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Re: change x0xb0x-LEDs

Post by antto »

i just hated the LEDs on my old x0xb0x, they were Red, but not very diffused, and when you look on top of them they were "okay" but if you look at an angle - you can no longer tell which are lit, which not, nor even which blink!

i had other Red LEDs which were better (more diffused) and i already built a x0x with them, so they looked great with 10K resistors
luckily, my old x0x had 10K resistors, so i had to only desolder the damn LEDs

is it easy? - well, you have to desolder 40 LEDs (and maybe 40 resistors) ... try not to melt any components with the iron

make sure you select the resistor value for the LEDs you have wisely, because you don't wanna regret it afterwards for the LEDs being "too bright" or "too dark"
take 5V from the power supply, get a bunch of resistors (or a pot) and hook one LED to it and to the 5V, play with it, see what kind of resistance is best (not too bright, yet bright enough)
when you're happy with that - go and desolder the stuff

then, for soldering the actual LEDs, the spacers are really good, but you also wanna have the front panel on, so they are positioned perfectly

Luap
 
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Re: change x0xb0x-LEDs

Post by Luap »

I've done this a couple of times. It is a chore.. Especially, as Annto mentions, if you have to change the resistors also. Which is quite possible with blue LED's as they tend to mostly be available in hyper bright retina burner form, so they need more resistance than your average LED in order to retain your eyesight.
So.. There is a fair chance you have 40 LED's and 40 resistors to remove, and resolder. You'll need to be reasonably good at reworking electronics, or PCB damage awaits. Generally, soldering parts is easy, it's removing them and managing to leave the PCB in a good state afterwards that can be tricky.

roxxx303
 
Posts: 93
Joined: Tue Nov 08, 2011 11:33 am

Re: change x0xb0x-LEDs

Post by roxxx303 »

Thanks for your tips! I think I will only change a few of them at first.
I found a formula in the forum by GUEST:

>there are 40 leds
>so if each led draws 10mA
>then you run the risk of exceeding the limit
>if you use 1k resistors
>you are gauranteed to consume less than 5mA per led
>so you wont hit this limit
>
>the way to calculate the current through the led
>is current =(5v - led voltage)/resistor
>red leds usually have 1.2v and green 2.4v and blue 3.6v
>guest

So I assume this calculation is right?:
blue: (5V - 3,6V) / 1000 Ohm = 0,0014 A = 1,4 mA
green: (5V - 2,4V) / 1000 Ohm = 0,0026 A = 2,6 mA
red: (5V - 1,2V) / 1000 Ohm = 0,0038 A = 3,8 mA

In the specs the blue LEDs (500 mcd 3,6 V) are 25 times brighter than the red ones (20 mcd 2,4 V),
so which resistor would you suggest?

Thanks!

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antto
 
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Joined: Thu Apr 15, 2010 3:21 pm

Re: change x0xb0x-LEDs

Post by antto »

the thing with these formulas is all nice, only that i can't visualise how bright the LED would be
that's why i recommend you try in practice, have a multimeter with you and test with a bunch of resistors (watch out with the low-value ones)

you can measure the current as well

i think you can measure the LED resistors in your x0x "in-circuit" (without removing them or lifting one leg)
at least that worked for me with R234

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altitude
 
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Re: change x0xb0x-LEDs

Post by altitude »

This is a bad idea IMHO. Get some blue LEDs and test a couple on a once on bread board before desoldering the 40 resistors

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