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Something Fried on my Propeller Activity Board? — Parallax Forums

Something Fried on my Propeller Activity Board?

GeeksGoneBadGeeksGoneBad Posts: 100
edited 2014-03-03 19:25 in Propeller 1
Hey all - I think I fried something on my Propeller Activity Board - when I turn it on now to position 1 both the 1 and 2 lights light up and I have input power at the servos when in position 1 or 2

any ideas what I might have fried?

Thanks
Jamie

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-09-10 19:37
    Do you have any components connected to the board?

    You may have power passing through some component to the servo power rail.

    What happens if you have nothing connected to the servo power line?
  • GeeksGoneBadGeeksGoneBad Posts: 100
    edited 2013-09-11 03:13
    Hi - nope no wires plugged in at all - and after playing some more with it I don't think it's fully working right either - I can blink an LED but I can't run servos or steppers off that other power rail even if the switch is in position 2
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-09-11 03:27
    Possible switch failure.
  • GeeksGoneBadGeeksGoneBad Posts: 100
    edited 2013-09-11 05:31
    Oh that would be nice if I didn't fry something that I couldn't replace - I might be able to replace the switch :)

    here's some more news - I realized that I plugged in a 12V adapter when the board says 6-9V :( would that fry the switch?
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-09-11 07:31
    Would 12V fry a switch that is good at 9V? It is hard to say, but I suspect that the switch was designed for higher volatages than that. Voltage rating is really about insulaton.

    The other side of the equation is Amps. A lot of amps might be a source of damage, or a simple flaw in manufacture. Or debris from your workspace ( bit of wire or solder may have gotten into the works).

    Amps x Volts equal Watts, so more of both can fry things.

    It is all rather speculative from afar. Signs of burning and shorting might indicate something. Put the backside of some boards on a conductive surface or atop a screwdriver might produce a dramatic failure.

    Can you verify it is the switch by by-passing it? You might be able to get your servos working again if it is a through-hole type switch. If it is surface mount, you'd have to remove the existing switch to do a by-pass. It would first be best to survey your power circuitry for what distribution is okay, and what is missing.

    There is always the alternative of not touching a thing and asking Parallax to provide repair. Is this the board with a "Lifetime Warrenty"? If so, contact Parallax.

    I suspect that apply 12V would first show as a very hot voltage regulator. In the good old days, some would get hot enough to melt the solder and have it slide right off the board... but they often provide a thermal shut down internally for that can happen.

    The switch might have failed from being positioned half way between 1 and 2 while you plugged in power. Such a position might cause harm in some switches when powering up. You have a bit of in-rush current to the capacitors.


    ++++++++++++++++++++

    I suggest you read all the CAUTION remards in the Propeller Activity Board Guide. pdf to determine what might have happened. Of course, something else might have happened.

    http://www.parallax.com/product/32910
  • Ken GraceyKen Gracey Posts: 7,392
    edited 2013-09-11 08:28
    Jamie,

    This isn't normal behavior as you noted.

    But first I need to apologize for us not addressing this issue more quickly. Looks like over 24 hours have passed and we could have gotten a replacement board shipped to you a day earlier. But it's only Wednesday today and with some quick shipping you could have a productive weekend in Florida, so please get me your shipping address via e-mail before noon today Pacific - use kgracey@parallax.com.

    As Loopy indicated, we happily stand by our products. The problem you report could be one from manufacturing or your own mistake - I don't know and it truly doesn't matter. Maybe David could report for whether or not we check for this issue as part of our test procedure. In either case none of us should have our precious Propeller time reduced by such a problem!

    Let's get you a replacement Propeller Activity Board shipped out today, UPS Blue, so you're back in action. And please let us know in these forums if you have any further technical problems.

    Sincerely,

    Ken Gracey
  • PublisonPublison Posts: 12,366
    edited 2013-09-11 08:39
    Ken Gracey wrote: »
    Jamie,

    This isn't normal behavior as you noted.

    But first I need to apologize for us not addressing this issue more quickly. Looks like over 24 hours have passed and we could have gotten a replacement board shipped to you a day earlier. But it's only Wednesday today and with some quick shipping you could have a productive weekend in Florida, so please get me your shipping address via e-mail before noon today Pacific - use kgracey@parallax.com.

    As Loopy indicated, we happily stand by our products. The problem you report could be one from manufacturing or your own mistake - I don't know and it truly doesn't matter. Maybe David could report for whether or not we check for this issue as part of our test procedure. In either case none of us should have our precious Propeller time reduced by such a problem!

    Let's get you a replacement Propeller Activity Board shipped out today, UPS Blue, so you're back in action. And please let us know in these forums if you have any further technical problems.

    Sincerely,

    Ken Gracey

    Outstanding Ken!

    Parallax is always to the rescue to service the great bunch of characters hanging around these parts. :)

    Jim
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2013-09-11 10:34
    David should know the details of the board and power requirements and I have notified him of this thread, so he should be able to respond shortly.
  • David CarrierDavid Carrier Posts: 294
    edited 2013-09-11 12:00
    Jamie,
    There are four MOSFETs in in a group above the "PARA" in the PARALLAX logo on the Propeller Activity Board PCB that switch the auxiliary power on and off. If you ramp the voltage over the 9 VDC max, those MOSFETs will blow before anything else. The board may still work, but it won't be able to deliver power to the servo headers, and the power LEDs might light up incorrectly. We can repair it if you send it back, but it looks like Ken is sending you a new one.

    If you want to keep using the damaged board too, minus the servo headers, either use a soldering iron or a pair of pliers to remove the MOSFET closest to the "RA" in the PARALLAX logo, as it can draw excessive power once it is damaged.

    — David Carrier
    Parallax Inc.
  • GeeksGoneBadGeeksGoneBad Posts: 100
    edited 2013-09-13 07:59
    Thanks for the reply guys! (now I'm the one lagging in response LOL)

    I'm 99% sure the problem was 100% my fault ;)

    Thanks for the advise on removing the mosfets - I will :)

    I have a few other boards to keep me occupied in the mean time - this forced me to break out the Propeller Minis I got :)

    You guys rock! Thanks!

    Jamie
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2013-09-14 03:41
    Apologies, with the advent of USB powered Propeller boards have begun to use MOSfets for switching the power distribution. While I did look at the board's schematic, I missed this detail as the schmatic is spread over quite a few pages.

    Live and learn.

    Generally, I also repair my own boards as it is a long way between Kaohsiung and Rocklin. But Parallax is wiling to help out. They do want to know about these faillures as they then learrn how to improve their designs.
  • John KauffmanJohn Kauffman Posts: 653
    edited 2014-03-03 18:20
    I agree with David: blown MOSFETs from high input voltage.

    I goofed once and suspected the power switch; same double green LEDs unexpectedly and a whiff that reminded me of a kid playing with matches near a duffle bag of ice hockey gear. Chris S. guessed from afar a wall wart gone bad. He noted that if not top quality they can short or 110/220 switcher go bad.

    Since it was dead I plugged in again for entertainment and it fulfilled: I had never seen a component actually glow re-hot.

    I have now developed the habit of having one finger on the mosfets when I turn the switch on. If it happens again I will detect the problem real fast.
  • Clock LoopClock Loop Posts: 2,069
    edited 2014-03-03 18:28
    John Kauffman wrote: »
    I have now developed the habit of having one finger on the mosfets when I turn the switch on.

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  • RaymanRayman Posts: 14,659
    edited 2014-03-03 18:29
    FWIW, I once had an issue that I traced back to customers using an unregulated 12V supply.
    Turns out that even though some power supplies say "12 V", unregulated ones will put out much more with no load...

    So, that's when I changed to 6..9 V specification for power supplies.
    Idea is that even unregulated supplies at 9 V wouldn't fry the power parts...
  • John KauffmanJohn Kauffman Posts: 653
    edited 2014-03-03 19:25
    A little burning is good for learning
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