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board of education working but not - bad LM2940CT? — Parallax Forums

board of education working but not - bad LM2940CT?

charlieknoxcharlieknox Posts: 27
edited 2006-12-15 00:57 in BASIC Stamp
I have a BOE Rev B with a BS2 mounted.· When powered up, the green power LED does not come on, and I get no 5 V at the Vdd terminals bordering the breadboard, however I do get 5 V at the AppMod Vdd socket and the Vdd pin on the BS2.· Program runs fine.· I could not find BOE Rev B schematic on parallax.com, but did find it for Rev C.· I'm suspecting the LM2940 is bad (no voltage at it's inboard pin), but the on BS2 regulator is giving me the 5 V at the chip and AppMod.· Please confirm/deny, and point me to the Rev B schematic.

Thanks !!!

Charlie

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-12-14 22:50
    Charlie,
    ·
    ·· That is correct.· On the Rev B BOE the AppMod VDD came from the BASIC Stamp on-board regulator.· It does sound as if your regulator is damaged.· I hope this helps.· Take care.

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    Chris Savage
    Parallax Tech Support
  • Martin HebelMartin Hebel Posts: 1,239
    edited 2006-12-14 23:14
    Charlie,
    Just a quick question, everything is disconnected from the board so it's simply not shorted out at this time?

    -Martin

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    Martin Hebel
    StampPlot - Graphical Data Acquisition and Control
    AppBee -·2.4GHz Wireless Adapters & transceivers·for the BASIC Stamp & Other controllers·
  • charlieknoxcharlieknox Posts: 27
    edited 2006-12-15 00:57
    Yes· Martin, there are·no loads connected.· I was using the board to generate random squarewave signals with a high low loop with pauses, to give my students practice with the oscilloscope, finding frequency, etc.· One never knows what unintentional errant damage can result.· freaked.gif

    Charlie
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