Onn 15" lcd

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  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK
    #1

    Onn 15" lcd

    A friend at work heard I repaired TVs so he brought this small one in for me to have a look at. Normally wouldn't bother but I thought there was nothing to lose.

    Fault: Not powering up. Standby red, pressing the button makes it flicker but it stays on red. Doesn't power up.

    Diagnosis: The 2.5V TS1117 regulator had failed. Before pressing the button, it measured 2.5V, but when pressing the power button it dropped to 2.33V. The TAB pin and 2nd pin of the IC was visibly discoloured -- a deep grey/blue compared to the outer two pins which indicated to me the device must have been badly stressed. In addition, a 470uF 25V capacitor near the LVDS output was bad (bulged), although it wasn't the cause of the fault.

    Fix: The TS1117 was replaced. TV works fine now. The capacitor was later replaced for reliability.

    This emphasises the need to test regulators while the unit is under load i.e. the fault must be occurring. It can't just be in standby.
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.
    Tags: None
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