Shop OBEX P1 Docs P2 Docs Learn Events
SX Key Heating up, pulling 400mA...Need help... — Parallax Forums

SX Key Heating up, pulling 400mA...Need help...

SteelSteel Posts: 313
edited 2006-09-19 22:40 in General Discussion
I am trying to program an SX28.· I am using the SXTech board.· There are no components plugged into it, and no external oscillator.

I have an 8.5V benchtop power supply powering it.

When I plug my SX Key RevF onto the board, the board begins pulling 400mA and The SXKey starts burning up.

When I connect a Serial cable, I get the message "SXKey not found on COM1"

Could my SX28 chip be bad?· The voltage levels are correct at VDD and VSS·.

Wierd....

Comments

  • cbmeekscbmeeks Posts: 634
    edited 2006-09-19 19:41
    Are you pushing 8.5V to the SX??? That will cook it. It should only be pulling 5V.


    EDIT:

    Oh wait, I didn't catch that you are using a tech board...I thought you were putting 8.5v into the SX directly. smile.gif

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Coders' Hangout
    A place for programmers to hangout!
    http://www.codershangout.com

    METROID?
    Metroid Classic
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2006-09-19 19:52
    Before doing anything else, please do the following, and double-check:

    - Disconnect the SX-Key from the SXTech board, and also pull out the SX28.
    - Make sure that the power supply has correct polarity, and then turn it on.
    - Take a voltmeter, and check if the voltage between pins 2 and 4 of the SX28 socket is 5Volts (+ at pin 2, - at pin 4). When it is remarkably higher, the on-board regulator may be fried.
    - When you have measured 5 Volts, disconnect power, plug in the SX-Key, oriented correctly and aligned with all four header pins. Do not insert an SX28 in the socket yet.
    - Turn on power again.
    - Does it still pull 400mA, and get hot?

    If yes, I have bad news - most likely, your SX-Key is fried - if not, your SX28 may be in semiconductor's heaven, so hopefully, you have another SX28 on hand to try.

    And ALWAYS turn off power before attaching or removing the SX chip, or the SX-Key!

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Greetings from Germany,

    G
  • SteelSteel Posts: 313
    edited 2006-09-19 21:49
    [noparse]:([/noparse]

    My SXKey seems to have gone onto better places....It is only pulling 200mA, but still Getting real hot.

    Thanks, Gunther

    *Sigh....
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2006-09-19 22:40
    Steel,

    sorry to read your message - 200mA is WAY too much for just the SX-Key!

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Greetings from Germany,

    G
Sign In or Register to comment.