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Propeller Chip getting hot — Parallax Forums

Propeller Chip getting hot

jaegjaeg Posts: 156
edited 2010-10-12 15:03 in Propeller 1
I got a Propeller Platform USB from Gadgetgagnster. It is running off of 4 AA batteries. I didn't have much time to test it out but I did have Rayman's touch screen module hooked up to it. It was running fine then the screen went blank. I figured it might be the screen and tested it. Then I realized that the chip wasn't letting me program the eeprom and when I picked up the board the chip was hot. There is nothing I can tell that is shorting the board. Sometimes the chip heats up fast sometimes slow. It can load ram but it doesn't execute anything it just leaves all the pins at ground level. I emailed Gadget Gangster about it but I wanted to ask here if there is anything I can do to fix it?

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-10-09 07:07
    That's a sign of a short circuit somewhere or, for some reason, a damaged Prop. You're going to have to work this out with GadgetGangster. In terms of a "fix" ... we're talking about going over the board with a magnifying glass and maybe a fine tipped soldering iron and solder wick material to see if there are any bad solder joints.
  • jaegjaeg Posts: 156
    edited 2010-10-09 07:15
    Ok thanks Mike. The fix is probably beyond my abilities so hopefully I can just get it worked out with GadgetGangster.

    Is it possible this might of damaged the touch screen module? Nothing on it got hot, smoked, or made a bad smell.
  • Mike GreenMike Green Posts: 23,101
    edited 2010-10-09 07:21
    "damaged the touch screen module?" ... who knows? You don't have to get smoke or a hot chip for there to be serious damage. On the other hand, we don't yet know what's wrong with your Prop board or how it happened, so it's impossible to tell whether that affected things connected to it.
  • jaegjaeg Posts: 156
    edited 2010-10-09 07:22
    True. Thanks for your help. I'll try to get this all sorted out.
  • RavenkallenRavenkallen Posts: 1,057
    edited 2010-10-09 07:57
    You might get a multimeter and use the continuity setting to check for a short across the power supplies. You could also check the regulator with the multimeter.
  • jaegjaeg Posts: 156
    edited 2010-10-09 08:26
    That was one of the first things I had check I didn't find a short. The voltage going to the prop is a consistent 3.3. I did find a blob of solder on the usb chip. I don't think I can remove it. My smd soldering skills is 0.

    EDIT - now that I look at the chip the legs look all messed up. I wonder if it was a manufacturing fluke.
  • RavenkallenRavenkallen Posts: 1,057
    edited 2010-10-09 08:40
    It all depends on what is getting hot... If the Prop itself is getting hot, that could be a problem with the Prop(That could also make the regulators hot to). Are the regulators getting hot?
  • jaegjaeg Posts: 156
    edited 2010-10-09 13:27
    Nope. Just the prop.
  • RaymanRayman Posts: 14,889
    edited 2010-10-09 20:29
    I've seen a few Prop chips that were hot. Not one ever recovered. So, sorry to tell you, but I'd guess it's toast...

    It's rather hard to kill a Prop. I've never been able to tell for sure what has killed it in the past... But, I vaguely recall putting 5V on the 3.3V Vin is a sure killer...
  • LeonLeon Posts: 7,620
    edited 2010-10-09 21:21
    12V doesn't do them much good, either. :)

    Someone mentioned running one at 5V recently, and didn't notice it for a while. That one survived.
  • jaegjaeg Posts: 156
    edited 2010-10-10 06:17
    As far as I know I didn't put any power where it shouldn't go. It ran of 6v from 4 AAs going through the power connector at the top of the board. Hopefully GadgetGangster will replace it if not I might have to perform micro surgery .... which is slightly beyond my skills.

    I'm worried about the screen. I have no way to test if it works or not. Will you be making new touchscreen boards Rayman? They are currently out of stock at GadgetGangster and if it is toast too I'd like to buy just the board since I already have the screen.
  • RaymanRayman Posts: 14,889
    edited 2010-10-10 18:14
    Yes, I'll make more. I'm a bit behind on inventory after vacation, but I'm trying to catch up...
  • jaegjaeg Posts: 156
    edited 2010-10-10 19:10
    Ok awesome. Hopefully I won't have to buy a new one but you never know.
  • CannibalRoboticsCannibalRobotics Posts: 535
    edited 2010-10-11 09:31
    The messed up pins and solder blob at a pretty big concern.
    Load some code that basically defines all ports on the prop as input. If it stays cool and responsive then start activating port groups and objects one at a time to see which one makes it hot.
    I've accidently I've heated up a few and gotten them back. I now use a varriable power supply to start up prototypes or newly manufactured boards. Turn it on at 3.4 volts and watch the current. If current climbs dramatically as I go on up then I back off and start VOM testing. I also watch at 5 and 12 volts when bringing up other parts of the circuits.
  • jaegjaeg Posts: 156
    edited 2010-10-11 13:00
    I had tried that. They all just stayed at ground state. It quit accepting eeprom and now it doesn't accept ram. I got a reply from gadgetgangster that they can't replace it. So I'm going to try removing the excess solder with some solder wick. If that doesn't work I guess I'll try to replace the prop chip itself. It might just be better for me to make my own board though.

    I think the blob happened after the prop messed up though. I don't remember it being there before so that's probably my fault. So chances are the prop needs changed.

    Any suggestions on how to remove the old prop chip?
  • CannibalRoboticsCannibalRobotics Posts: 535
    edited 2010-10-11 13:16
    The problem is getting all of the pins hot enough to release simultaneously without frying everything in the hood and/or pulling up traces. Only way I've ever done it successfully was with a hot air rework station an those work beautifully.
    Rework stations are allot more expensive than props or boards but I think it's paid for itself numerous times over.

    Oops: did remember that you can use a Dremmel tool and grinder wheel to cut prop pin connections individually. Once you've cut all pins and removed the plastic case you can use a fine tip soldering iron and solder wick to clean off the remnants and pads individually. Be real careful though when you are cutting the last few make sure the chip does not jump and tear the traces.
  • jaegjaeg Posts: 156
    edited 2010-10-11 13:21
    Being on a college student budget I probably can't get one of those. So I guess I'll just either build my own board or use a protoboard from parallax. There really isn't any spectacular features of the propeller platform board anyway and I'm sure I can hard wire the modules to it. I'd rather just get something new than trying and failing to fix something and be out even more money. Thanks for all the help guys.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-10-12 10:46
    Your fears about the video screen are very understandable. From experience, the worst thing you can do to one is reverse polarity. Is that a possible source of error?

    The regulators have thermal shut down and that may have protected the screen. Some regulators have reverse polarity protection as well. But you really can't know if the video is okay until you test it with a safe working micro-controller.

    I hate to say this, but my experiences with reverse polarity are instant death to LCDs. If the video screen doesn't have reverse polarity protection of some sort, as little as 0.5 volt may cause disaster.
  • PavelPavel Posts: 43
    edited 2010-10-12 15:03
    I can remove the dead chip and replace it with a new one for you (you just have to mail the board to me). I cannot promise that I can make the board work but if it's just a matter of fixing some solder blobs and replacing a few chips, the odds are not miserable. Let me know.
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