Salam dear friend, i'm professional in this work,
Listen, some times 4 led's did not work fine in series, make series of 2 led's, then install 380 ohms resistor in both series to negative (-) point and install 1amp diote on positive (+) point, but be carefull while installing diote, b cz diote have two sides, + ve and -ve, conect +ve side to +ve point of series, diote have white or silver mark on +ve side.
Cheers!
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