Swapping Out LEDs to Change Color
jedihobbit
Central Virginia, USA New
As part of the “as yet to be named†build I plan on replacing the blue LEDs that are part of the Zalman ZM850-HP that is in its future. Currently they are the usual “blue†and wish to replace with green.
While I have no issues with de-soldering and soldering, component selection will be. In my limited knowledge I believe I’ve read somewhere that just because it is an LED doesn’t mean they are all the same. Soooo was wondering if there may need to be a resistor or something that will need to be in the circuit? :confused2
While on the subject of soldering, as I don’t do that much and no longer have a soldering tool…….which would be better the traditional “iron†or the racing looking “gun�
While I have no issues with de-soldering and soldering, component selection will be. In my limited knowledge I believe I’ve read somewhere that just because it is an LED doesn’t mean they are all the same. Soooo was wondering if there may need to be a resistor or something that will need to be in the circuit? :confused2
While on the subject of soldering, as I don’t do that much and no longer have a soldering tool…….which would be better the traditional “iron†or the racing looking “gun�
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Comments
You will almost certainly need a current-limiting resistor but to size it you need to know the LED supply voltage and the supply voltage from the power supply. If it's an LED fan then the latter is probably 12V. The equation Rl = (Vs - Vl)/Il will give you the value of the LED current limiting resistor Rl for supply voltage Vs, LED rated voltage Vl, and LED rated current Il. That information will be in the LED datasheet.
I prefer a soldering pencil for this sort of work. I have a really nice Metcal soldering station but the Weller 25W or 30W pencil is perfectly adequate. The gun is for soldering big hunks of metal like copper pipe or power conductor and will probably melt/set fire to your PSU's guts. You'll want to get some fine-gauge 63/37 rosin-core lead solder; 60/40 lead is okay but the green lead-free stuff sucks. For splicing wire you'll get good results by tinning each conductor with a small amount of solder and then sweating the conductors together.
To be totally honest though, you'd be better off just replacing the LED fan as an assembly. Buy one that's the same size as the one inside your power supply with a nice bearing and the LED you want and solder that in place of the old one.
They seem to work but I am now worried about their lifespan?
As a rule of thumb, you can go from longer wavelength LEDs to shorter wavelength LEDs without changing the resistor though you'll lose some intensity as you'll be driving the new LED at a lower voltage. Going the other way you need to modify the resistor since the short-wavelength LEDs require higher operating voltage than what the long-wavelength LEDs are rated for.
No hijack that I noticed! :bigggrin:
Hope to have some parts to play with by next week. I'm sure the assembly I'll be attacking has the resistors hardwired. Will just have to see if an extra will need to be inserted or if a total replacement will be required.
http://ledcalculator.net/