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DLP Lightcrafter stop working (only D3 is on)

Can Can
Prodigy 80 points


Hi,

We want to use external trigger signal to control the lightcrafter to display images at different times. Therefore, R285 is connected on the board.

Pin 1 on J7 is connected to 3.3V

Pin 2 on J7 is connected to trigger signal

Pin 4 on J7 is connected to GND

The lightcrafter worked fine until Pin 1 was accidentally connected to GND. The lightcrafter stopped working. We tried to reboot the lightcrafter alone. The lightcrafter didn't boot up.

We think this accidence may cause a short circuit somewhere on the board.

When the power is applied to lightcrafter. The red LED (D3) is on for a second. Then the green LED (D2) is on for a second. After that, D3 is continuously on. D1 and D4 are off all the time.

The upper board of the lightcrafter is working fine because we put the upper board on another working lightcrafter and it have no problem to boot up. Therefore, we think there is a problem on the bottom board. Can you give us a hint how to track down the damage?

Many thanks.

CanCan

  • 0
    TI__Intellectual 1565 points

    Hello CanCan,

    From what you described, looks like connecting  Pin 1 of the J7 connector to GND has definitely caused a short on the board. If you would still like to trace the damage, you can refer to the board schematics ( DLP LightCrafter EVM Reference Design)  on the DLPLIGHTCRAFTER product tool page  (http://www.ti.com/tool/DLPLIGHTCRAFTER)

    You can find the connector J7 on the page 13 of systems board schematics.

    Hope this helps.

    Regards

    Manasi

  • 0 in reply to Manasi Navare
    Prodigy 80 points

    Hi Manasi,

    Thanks for your suggestion. We tested our board. The upper board worked fine when we attached it to a functioning bottom board. Therefore, we believed the problem is about the 3.3V power supply on the bottom board which doesn't work properly.

    Here is the tracing:

    Pin 1 at J7 (Trigger Interface on p.13, dlpr003.pdf) = 0.24V

    Pin 1 & Pin 3 at J8 (System Board interface Interface on p.16, dlpr003.pdf) = 0.24V
    Pin 1 & Pin 3 at J7 (Board interface Interface on p.9, dlpr002.pdf) = 0.24V

    We can't measure the TP39, TP40 and T41, TP38 on the bottom board without removal of the upper board.

    ----------------------------------------

    We disconnected the upper board, tested the bottom board alone.

    We found MSP_PWREN_CORE and MSP_PWREN_INTF (Pin 21 and Pin 22 at MSP430, P8, dlpr002) are low.
    Therefore, U15, U16 and U17 are not working.

    We understand the MSP430 has a power up sequence. We think without connecting to the upper board. The MSP430 won't start up properly. Could you suggest a better way to test the power supply (especially P3P3V from U15) on the board?

    Thank you very much.

    Can