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[SOLVED]820-3209 - no backlight (no feedback continuity)

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  • [SOLVED]820-3209 - no backlight (no feedback continuity)

    I have this 820-3209 board that was liquid damaged around the lp8550 so I removed the it and replaced it as well as all the components around it.
    With the lp8550 removed i did a continuity test from the feedback pad to the probe(938) as well as from the probe(938) to pin 2 of L9701 and there was no continuity for either one. Also when I measured the output caps in diode mode it measured 0.40v which I believe means the feedback line is broken

    I put a new lp8550 on to shove my 36AWG to the feedback ball and run it to the probe(938) but while doing that I ended up ripping the probe point pad. Can I just run the wire from the feedback ball straight to Pin 2 of L9701?


  • #2
    Which feedback are we talking about here? Usually it is ball A5 that has the bad trace. If it really is B1/B2 then both those balls will need to be connected. I see no issue with soldering directly to L9701 as long as it goes where it needs to.

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    • #3
      Sorry. I was referring to the A5 ball.

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      • #4
        A5 goes to the backlight output, so easiest would be cathode of D9701.

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        • #5
          Okay thanks. The board is now fixed. You can mark as solved.

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