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What was that guy going on about?

Discussion in 'General Electronics Discussion' started by ZeroDivided, Feb 1, 2014.

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  1. ZeroDivided

    ZeroDivided

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    Jan 31, 2014
    Sorry for the stupid title. Noob stuff ahead:
    So I went to my local electronics store today to buy a cheap Weller soldering iron, but they only had the stations so I ended up buying one with a temperature controll from their house-brand. Well, thing is: The guy who sold it to me asked me what I wanted to do with it (trying to fix an old Gameboy), and he just started pouring stuff on me and I just didn't keep up, and then he had another customer and told me he'd be back in 5, but I just didn't see him anymore and left after a bit. So I thought maybe someone here could help me out. Only thing I ever soldered was a radio kit, which was fun but more of a paint by numbers kind of deal, so I basically know nothing, and now I'm slightly frightened.

    First he ask me if that thing had components on it that are sensitive in some way I don't remember, then he was going on about the grounding on the soldering iron and taking something out of the soldering iron. I know what grounding is so my mind got stuck there for a second, next thing I remember is him going on about getting an old pen and doing something to it with a nail and a capacitor or resistor, I don't remember which anymore because by that time I was thinking about dying a horrible death. Well, he said I could pat down the circuit board with that pen contraption.

    Basically I understand that some parts can store electric charges (sorry for sounding dumb) and that this can be kind of dangerous, and that grounding is kind of important for not dying, but that's all I could put together from what he told me. I have no idea what I should look out for, or do to not kill myself.

    I was hoping that someone maybe has some idea what the guy was on about and enlighten me, because I kinda like not dying (it's a thing I'm known for doing). Basically the things the Cartridges go into broke on a GameBoy Pocket, and I wanted to replace it with one from another GameBoy Pocket, because fixing stuff instead of throwing it away is kind of nice.

    Let me know what you think!
    [​IMG]
     
  2. BASICFreak

    BASICFreak

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    Jan 30, 2014
    Well, lots of devices have capacitors in them, which are designed to store a charge. But because you're working on a gameboy (which if I remember right runs on 3V DC) only thing I would suggest is keep yourself and your tools grounded to avoid a static discharge on an IC.

    If you were working on something with a higher voltage I would suggest making sure all capacitors are drained - I still suggest it - at 3V you could feel a "bite" but your body wouldn't mind too much.

    I highly recommend practicing solder joints on something you feel fine tossing in the trash, it's not that hard to do but does take some practice.



    P.S. I realize it's the Amps that kill not Volts, but the gameboy doesn't use much current it runs for hours on two AA batteries.
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,482
    2,830
    Jan 21, 2010
    BASICFreak has noted the potential for problems with charged caps, but of far greater concern is for electrostatic (or indeed thermal) damage of sensitive electronics.

    On a battery powered device that does not generate any high voltages internally, you can basically ignore charge on capacitors as a personal safety issue (and the chance of you feeling 3V -- none, you might notice the discharge of a particularly large capacitor charged to that voltage though if done through a screwdriver).

    The risks to yourself in soldering on a gameboy are limited to being burned by the soldering iron (or something heated by it) and having to shell out for a new one if you break it beyond repair.
     
  4. BASICFreak

    BASICFreak

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    Jan 30, 2014
    How could I forget heat sensitive devices - Work quickly on each lead and take breaks to avoid over heating a component. Should take between 5 and 10 seconds per lead. (pulling number out of thin air)
    I usually take a break every 60 seconds to allow things to cool, also helps avoid burning your hand even if the components are not heat sensitive.

    Yea and after I posted I put it in a calculator - 3V cannot get through the resistance of your skin. 3V can't get more than .05mA through 60K ohms -the resistance of dry skin is usually between 1,000-100,000 Ohms which could get 0.03-3mA at 3V and that's just the skin layer.
     
  5. ZeroDivided

    ZeroDivided

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    0
    Jan 31, 2014
    Very good to know! Thanks guys! Now I'm also getting results from Google! I think I remember that resistors don't have a polarity so that's one thing less to worry about.

    For the sake of learning: So, if I had something higher voltage, I'd just take a resistor and carefully touch the legs of the capacitor to let it discharge/drain. I guess I should just use the biggest resistor I can find for that, if I make myself a little device to do that with?! Do I have to do that to every single capacitor? There are some electronics that are simply loaded with those - I imagine that would be a bit of pain.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,482
    2,830
    Jan 21, 2010
    In general, you're only going to be worried about capacitors that are used for storing energy. In most cases they're in the power supply. (beware of things that you might not associate with being a power supply)

    The risk increases with voltage and physical size. Don't work on devices with internal voltages above 24V or so and you don't have to worry too much about voltage (the exception might be those with a capacitance measured in Farads - or tend or even hundreds of Farads)

    You can build a device to discharge capacitors, but I've only use them for capacitors holding maybe a couple of hundred volts or more. I built one when I was routinely working with capacitors of maybe 2200uF with 330V across them. Capacitances much smaller than this can give you a nasty kick at these voltages. 2200uF @ 330V was easily enough to kill -- although I never tested that out.
     
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