Thursday, September 5, 2013

Looking into the crystal ball........kinda

It's crystal time
With posting about the toroid's I did get a little ahead of myself........I did say and I will post regarding Bi-filar toroid's but first I wanted to take a step back to the crystals. These were mounted and can's grounded well before you have to do the toroid thing! I wanted to take this post to look at the crystals both their mounting and the grounding of the cans. First off as I have said WAY to many times but I say it because it's important and can save you a POOP  load of time and that is to make sure you CAREFULLY  inventory your crystals. Problems can arise if you mount them in the wrong spot.....your alignment and testing can turn into a nightmare! Once these babies are in they are hard to remove and adding the extra heat to remove them can destroy them. So lets spend a moment on mounting them to the board. Here is what I do........
Installing the crystals
1. I check and double check to make sure I am mounting the proper crystal and mounting it in the proper place.
2. I tape the crystal in place by using some painters masking tape (very easy to remove) with a row of crystals I will run one long piece of tape across the top of the crystals and then to the board. Don't worry about a flush fit to the board at this moment that can be tweaked once the crystal is in place.
5 crystals that were taped
3. At SHORT INTERVALS solder the crystals in place. You don't want to heat the crystals up to hot as they can become damaged. are only soldering one leg of each crystal at this time.
4. Remove tape and reheat each leg single soldered leg while pushing down on the crystal to seat in firm and square on the board. Again applying heat at short intervals.
5. Solder all second legs of crystals and then trim flush with board.
Grounding the can of the crystal
Now comes the fun part and when you really have to take your time and check and double check things. I like to make the final build look as neat as possible and here is a step that takes some to to get it right. In the kit building process the manual has been asking you to keep the clipped leads and this is where they come in handy. You can take these clipped leads and use them to ground the cans of the crystals. Again care must be taken to not heat the crystals up to much as to damage them. I have a few trick up my sleeve to help the builder to avoid heat damage while grounding the can.

Here are the steps I do to ground the crystal can's
  1. I find a discarded lead in my container of "discarded leads" I take my time to shape the lead to fit neatly on the top of the crystal (some leads you are told to solder to the side as well). 
    Add flux to top
  2. I then add some flux to the top of the crystal to be grounded and then add some solder to the top of the crystal. The flux allows the solder to flow nicely and not much heat is needed to do this. 
  3. I then fit the preformed ground lead in place. I make sure the lead has an extra long tail as it goes through the board. This way I can hold it in place as I add a little solder to the soldering iron tip and then tac the ground lead to the top of the crystal. 
  4. Making sure the lead looks neat I then solder the lead at the circuit board.
    All done
  5. I now can go back to the top of the crystal and add more solder if needed. 
I find this way allows me to not heat the crystals up to much and possibly damaging them.  For side mounted ground leads I follow the same method and it seems to have worked very well for me.
Keep the spare leads

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