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Need help picking a circuit board for my flashligh

  • desolder Top 10 Forum Poster Friday, November 11, 2016 2:31 PM Reply

    I am unable to make out the traces on the LED board. Do you think you can use a better camera, and photograph from different angles, or use brighter lighting? You should be able to make out the traces yourself. They will appear as slightly raised areas on the surface of the board. Those are the copper traces which are painted over by the white paint.

    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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  • gasbag11 Top 10 Forum Poster Friday, November 11, 2016 9:21 PM Reply

    The backround in those pics is pretty clear, so I think he had the driver too close to the camera.

    NO! I don't know why DX screwed up the site so badly.
    Ask them.
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  • jimasbill1 Saturday, November 12, 2016 7:22 AM Reply

    Hope this helps


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  • desolder Top 10 Forum Poster Saturday, November 12, 2016 7:37 AM Reply

    Much better! It's wired 5S3P. That's a little surprising since the battery is only 4S. The LEDs will be very under-driven. But that is probably a good thing since 15 XMLs going at full power would probably cause the flashlight to overheat.


    The existing driver is a simple PWM dimmer. But a buck mode driver should work. If you can get it to fit, sku.50025 should work. Otherwise, try the one on ebay that I linked to.


    Can you post a better photo of the driver? The 78L "OS" is probably a 78L05 regulator. Those are easy to find.

    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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  • jimasbill1 Sunday, November 13, 2016 12:23 AM Reply

    Here are some better pics. The small driver I bought 2 weeks ago but it's to small. mine is about 1 1/8 across the face. The small one is 26mm I think. U2 is the broke one.


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  • desolder Top 10 Forum Poster Sunday, November 13, 2016 12:39 PM Reply

    Is the broken chip the small chip with three small legs , one wide leg, and marked "78L05"? That is most likely a LM78L05 voltage regulator in the SOT-89 package. You should be able to get those on ebay. But before you do, you should confirm it is really broken. For that, you should measure the output voltage to see if it is 5v or not. Download the datasheet for the LM78L05 to identify the pins.

    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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  • jimasbill1 Monday, November 14, 2016 7:59 AM Reply

    Yes it's the small chip. I've got a volt metter but not sure how to test it. I'll go ahead and see if I can buy the chip on ebay. What do you think if I used the small driver that I showed in one of the photos? It's supposed to be compatible. It's almost to the point of saying f-it and buy a new flashlight. I do want to thank you very much for your help. I've learned a few things You can never know to much.

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  • desolder Top 10 Forum Poster Tuesday, November 15, 2016 1:29 AM Reply

    Connect the driver to a 12V to 15V power supply. Or you can use a 12V lead acid battery or a 3S or 4S lithium ion battery. The positive lead of the power supply should connect to the driver's positive battery spring contact. The negative of the power supply should connect to the copper ring around the edge of the bottom of the driver (circling the positive pad and spring). You may need to temporarily solder a small jumper wire to this negative ring.


    Once the driver is connected to a power source, measure the voltage across pin 1 (Vout) and pin 2/tab (ground). It should be 5V. If not, then the chip is probably fried. If you don't know what pin is what, see this datasheet:

    http://www.st.com/content/ccc/resource/technical/document/datasheet/15/55/e5/aa/23/5b/43/fd/CD00000446.pdf/files/CD00000446.pdf/jcr:content/translations/en.CD00000446.pdf


    What do you think if I used the small driver that I showed in one of the photos?

    Did you buy that driver on DX? What is the SKU number?

    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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    post edited by desolder on 11/15/2016 at 1:31 AM
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