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I've killed a Project Board. — Parallax Forums

I've killed a Project Board.

HughHugh Posts: 362
edited 2014-07-07 13:09 in Propeller 1
I appear to have killed a brand new Project Board.

With the USB connected and 12V supplied to the board (in order to support the demands of an LCD) the 12V supply dropped out (literally fell from the connector I was using) and the PB died - I assume because the USB supply couldn't cope on it's own.

Is this a plausible theory? There's neither power light nor comms with PC.

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2014-07-07 06:25
    Hugh wrote: »
    the 12V supply dropped out (literally fell from the connector I was using)...

    What does that mean?
  • HughHugh Posts: 362
    edited 2014-07-07 06:27
    PJ Allen wrote: »
    What does that mean?

    The 12V connector was physically plugged in, but then fell out.
  • kwinnkwinn Posts: 8,697
    edited 2014-07-07 06:31
    Almost anything is possible but I would do a bit of checking before holding a funeral for the board. Start by checking the board using a Vin of 6 to 9V with nothing else connected to it and verifying the 3.3V is ok.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-07-07 08:40
    Hugh wrote: »
    The 12V connector was physically plugged in, but then fell out.

    The Project board doesn't come with a connector does it? Could the socket and the plug you were using be mismatched?

    The center post on a lot of barrel connectors are 2.1mm but some are 2.5mm. If your jack and connector weren't the right size, they wouldn't stay together as well as connectors intended to work together.
  • HughHugh Posts: 362
    edited 2014-07-07 12:33
    Applying power makes this component red hot within a second or so. (Ouch!)

    PB.jpg
    PB.jpg
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    PB.jpg 119.4K
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-07-07 12:40
    Hugh wrote: »
    Applying power makes this component red hot within a second or so. (Ouch!)

    How are you applying power? Is this the 12V you spoke of earlier?

    Is it possible the polarity was reversed?

    Was the board on any metal which could have caused a short on the bottom?
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2014-07-07 13:05
    Generally, a sudden disconnect of 12v power should not do any harm.

    The device that is hot is the switching regulator that is supposed to supply up to 1.0 amps at 3.3 VDC. How much of a load from the LCD are you putting on it? Are you trying to power the LCD's backlighting as well?

    I haven't located and read the switching regulator specifications, but if it does have an over-temperature and/or over-current shut down, it may revive once you stop overloading.

    Can you run some tests without all the extra load, like a "Hello World"?

    Reverse polarity is often a big disaster. It would likely destroy just about anything it contacts. And if you place you board on a messy table, tools and wire under the board could short all sorts of unexpected ways. Of course, a metal table is also a bad idea.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2014-07-07 13:09
    Yes, it is an RT8250 and does include thermal shutdown protection. Please rewire to something less power hungry and start over when it is cold.

    The board provides a diode to protect against reverse polarity reaching the switching regulator.

    You might also you have a short circuit somewhere that has gone unseen. These can be in the form of tiny solder bridges no bigger than a human hair. I have to look for them with a 20X jewellers loupe.

    But considering the built-in protection, you just may revive the board if you check all your wiring, soldering, and verify your loading is less that 1 amp.

    http://www1.futureelectronics.com/doc/RICHTEK/RT8250GSP.pdf
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