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LED changing on cellphones

Discussion in 'Techno-Magic' started by Disciple of The Watch, May 17, 2007.

  1. Disciple of The Watch

    Disciple of The Watch Preparing The Coming of The New Order Veteran

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    Remove all ads!
    I've has this question of my mind for quite some time, and I've asked Kitrax about the issue, but unfortunately, he couldn't really help me out, so I decided I'd take a chance and topic it in case someone happens to be more of an electronics nut than I am.

    Not surprisingly, I operate a small cellphone-related buisness (or more of a service since I make next to no profit whatsoever) during my spare times, and recently, I've had a couple inquiries regarding LED changing - old Noks, Motos . Ericsson - hell, even Siemens - owners wanting to change the color of the LEDS (blue comes out pretty often, so does red and orange), or owners of more recent phones looking to get keypad LEDs changed, amongst other things.

    There's definitively a market (albeit a small one), so I'm thinking it might be worth learning how to change them.

    I've studied a few phones, and I have rough drafts of where the LEDs are situated, but problem is, I can't for the life of me determine which side is the cathode and which one is the anode. Soldering in the new LED on the wrong side is something I definitively want to avoid.

    So, with that in mind, any way of differentiating the poles of the LED? I'm pretty much a noob when it comes to dangling with electronics.
     
    Disciple of The Watch, May 17, 2007
    #1
  2. Blackthorne TA

    Blackthorne TA Master in his Own Mind Staff Member ★ SPS Account Holder Adored Veteran Pillars of Eternity SP Immortalizer (for helping immortalize Sorcerer's Place in the game!) New Server Contributor [2012] (for helping Sorcerer's Place lease a new, more powerful server!) Torment: Tides of Numenera SP Immortalizer (for helping immortalize Sorcerer's Place in the game!)

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    I imagine you're talking about the LED's already in the phone. There isn't really a way to tell for sure; it depends on the manufacturer, and sometimes the only way to know is one lead is shorter than the other which goes away after the LED is installed and the leads are trimmed.

    That being said, you can tell by using a voltmeter to measure the potential difference across the LED: if it's positive, your common lead is on the cathode; if it's negative, your common lead is on the anode. Or even easier, just touch the leads of your new LED to the leads on the one you want to replace and install it the way it lights up.
     
    Blackthorne TA, May 18, 2007
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  3. Kitrax

    Kitrax Pantaloons are supposed to go where!?!?

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    Heh...you're still on this quest, huh?

    There's a few things I need to mention...
    First, like BTA, said...the voltmeter might be your only way to tell the cathode from the anode. Second, 90% of the time, the LEDs are going to be board mount. Soldering board mount components takes a lot more skill than soldering a standard component...the two solder points are a lot smaller, and usually extremely close to other solder points. A soldering iron isn't ideal for board mount components...solder pots are what you should be using.
    With that out of the way...you are going to need to know the output voltage and current for LEDs on each cell phone, and buy replacement LEDs that can handle those values.

    If you're still willing to mess around with board mount stuff...try practicing on a phone you don't care about. Let us know how it goes. :rolling:
     
    Kitrax, May 21, 2007
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  4. Disciple of The Watch

    Disciple of The Watch Preparing The Coming of The New Order Veteran

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    Quick update...

    I've studied a couple of phones, and I have rough schemes of LED placements and such stuff.

    Figuring out the cathode and anode remains a problem, but the trusty voltmeter is on the shopping list.

    And Kitrax, soldering pots may be better, but they're horribly expensive (saw a model that chings in at 800$ :eek: :eek: :eek: :eek: ) and I don't really have this kind of dough to stash on something I won't be using THAT often.

    On the plus side, I've been looking at soldering irons with micro tips, and there are a few ones that seem to fit the bill, but I can't really decide between the Weller WM120, WP25, or the SP12. Since I'm working with micro components, lower wattage seems to be the way to go, but then again what do I know.

    Thoughts?
     
    Disciple of The Watch, Jun 2, 2007
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  5. Kitrax

    Kitrax Pantaloons are supposed to go where!?!?

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    Solder Pots are just like everything else. There are the cheap ones, and then there are the overly expensive ones. The first model listed in that link is only $71. That's really all you need.

    And yes, a lower wattage is better for board mount...unless you like the smell of melting plastic. :nolike: :rolling:
     
    Kitrax, Jun 3, 2007
    #5
  6. Blackthorne TA

    Blackthorne TA Master in his Own Mind Staff Member ★ SPS Account Holder Adored Veteran Pillars of Eternity SP Immortalizer (for helping immortalize Sorcerer's Place in the game!) New Server Contributor [2012] (for helping Sorcerer's Place lease a new, more powerful server!) Torment: Tides of Numenera SP Immortalizer (for helping immortalize Sorcerer's Place in the game!)

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    Not that I'm an expert, but for PCB soldering, wouldn't you need a wave or fountain solder pot? The one above and ones like it are more for dipping things like jewelry or something aren't they?
     
    Blackthorne TA, Jun 3, 2007
    #6
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