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How do you disable the crystal on the Quickstart? — Parallax Forums

How do you disable the crystal on the Quickstart?

lardomlardom Posts: 1,659
edited 2017-02-14 15:41 in Propeller 1
I have a Quickstart board that will flash LED's but it won't communicate with the Parallax serial terminal. I want to replace the on board smt crystal with a through hole one.
The Quickstart layout PDF calls R13 a shunt which, if removed, will allow you to use a through hole crystal. Can I just snip it off?
Quickstart layout.PNG
1152 x 772 - 379K

Comments

  • PublisonPublison Posts: 12,366
    Yes you can remove R13, and use a through hole crystal in the X2 position.

    It is very unusual for a crystal to fail. It sound like the PLL on the propeller chip might have gotten damaged.
  • lardomlardom Posts: 1,659
    Thanks. It 'IS' unusual. I had no clue until I recently discovered why I was having problems with a custom PCB. I have several Quickstart boards that I like keep connected to different projects. It'll be nice to get this one back.
  • Cluso99Cluso99 Posts: 18,069
    Easier to use a soldering iron with a little extra solder and as you heat the resistor on top, just push it sideways until it slides off the pads. If you are lucky, it will stick to the tip of the iron. Then just clean up the pads, ensuring they are not shorting. Since you won't be putting the resistor back on it doesn't matter if there is solder left on the pads as long as they don't touch your crystal can. Note the resistor should not be used again as you no doubt have overheated it and its resistance will likely no longer be in tolerance.
  • lardomlardom Posts: 1,659
    Cluso99, I ordered some needed components today that I put it off because they were the small items where postage becomes the major cost.
    Personally, I think I destroyed my crystal when I desoldered it. While I have a desoldering iron, copper braid and a desoldering pump I need practice.
    I think I'll find something to practice on.
  • MikeDYurMikeDYur Posts: 2,176
    lardom wrote: »
    I think I'll find something to practice on.


    Salvaging parts from circuit boards in outdated electronics is good practice. A little more solder and some persuasion, or the vacuum + braid and some persuasion. It is the combination that works, as long as the heat isn't to high. A propane torch is useful on components with numerous pins. It is an art.

    Parallax boards are heavy duty, it would take alot of abuse to pull the print, especially on through hole.
  • lardomlardom Posts: 1,659
    edited 2017-02-18 22:26
    Well, I guess I do have a damaged pll. I temporarily soldered a brand new crystal into my Quickstart board and eventually tried
    setting the clock frequency in a child object in a new cog hoping that the problem was limited to cog zero.
    I could only get it up to 19,200 baud before I got garbage on the serial terminal.
    Oh well, I guess it's still usable. I can still find something to use it for. :frown:
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