newbie - simple questions on project

Discussion in 'The Projects Forum' started by meestahelectro, Aug 10, 2006.

  1. meestahelectro

    Thread Starter Member

    Aug 10, 2006
    28
    0
    Hi. Ive recently beomce interested in electornics... to start i took apart an electronic scale the other and planned to desolder the pieces and put it into a breadboard and then take it apart and the resolver it all back together. Logically this to me seemed like a great way to learn how the circuits work, use my DMM and of course practice how to solder.

    However, to my surprise and amazement, when i looked at the circuit boards that were part of the scale, there seemed to be only a few components that I recognized, some wires, some capacitors, etc. many of the items soldered onto the board were extremely small. I mean really really minute. I couldnt even in some cases hardly see them under the solder... are these just really small componenets? How the heck can I solder/desolder something this small.

    Was this scale meant to be disposable of some sort... never to be desoldered?

    Any guidance or advice is welcome. I've read a few books now on electronics, but probably havent even touched the tip of the iceberg?

    Any good diea on projects. My ultimate goal is to be able to fix circuits on my pinball machines when/if they ever were to break. Right now that are fine.

    Thanks,
    Marc
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    You have just come eye-to-eye with surface mount components. They can be replaced, but it helps to have speciaized soldering equipment. They only work on printed circuit boards, so they are no good for breadboard experimentation.

    What you need are called "through hole" components. They have leads and are large enough to be handled easily.

    You might look at www.circuitspecialists.com. They have educational kits and good prices on solderless breadboards.

    It is hard to get experience with electronics. Most equipment is not repairable, so the neighborhood repair shop no longer exists. Kids used to be able to walk in and learn something. Another problem is that nothing comes with a schematic any longer, so you have nothing to go by if you open up the case.

    If you look through this site, you will find a lot of information and experiments that are reasonably instructive and affordable. That's a good way to get started.
     
  3. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
    2
    I repair surface mount electronics. We use a microscope made for it. There are boards for surface mounted components that allow them to be used in breadboarding but you still have to solder them on.

    Since your eyes are probably better than mine you could probably get away with a magnifying headset http://www.action-electronics.com/magnifiers.htm

    It's a hassle and for most components you can still get through hole packages which are easier to deal with for people.

    The soldering iron I used was not fancy but did have expensive tips. I was not working on the ultrafine surface mounted components or I'd have been using some automated tools.

    Normally you don't repair the electronics but this was for a defense contractor. There were no replacements available so even badly burned or broken boards have to be repaired.
     
  4. meestahelectro

    Thread Starter Member

    Aug 10, 2006
    28
    0
    thanks... both answers shed some light onto my eager to learn mind...

    1. with regards to the surface mount components, how do you go about removing them... do you just use standard desoldering tools?

    2. what kind of tips are you using? I was told to get 1/16th chisel tips II havent gotten them yet) and to use a weller wes50 soldering station.

    3. do all electronic gadgets nowadays use these surface mount components?

    4. is it possible to look at the surface mounts and the circuit board and draw the circuit on paper, or are there hidden connection which cant be seen with the eye (or magnifying glass)

    thanks for any help. rgds, Marc
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    Some rework stations use hot air to melt solder at both ends of the device simultaneously. And you use fine tipped pliers or tweezers to grip the part.

    Be aware that markings are hard to make out, and that some capacitors are not easily distinguished from resistors. As to making up a schematic, it can be a challenge, as markings are only on one side, which may be on the down side. Boards may have multiple interior layers with traces routed invisibily from one point to another

    Having a fine tip is good. Heat is another matter. Moder solder is mostly lead-free. It is 98% tin and 2% silver, and melts at a higher temperature than tin-lead solder. The soldering tip will need to be hot enough to melt the solder quickly, so you don't heat the device excessively, causing it to fail. That's mostly technique - learning to do the joint in the minimum time. Sometimes devices like ic's are held in place by a dot of glue so they don't move before soldering at the factory.

    Not everything is surface mount. It requires robotic equipment to do it in volume.
     
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