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I am installing 5V 1903 chip 3-wire LED-strings in model buildings and have constant issues with Brown-outs and getting white to be #)*% white. Have also used WS2011 which are pretty similar and cross compatible (+ - Data)

  1. Brownouts- I inject power at twice the recommended interval and still get purplish whites and off colours. My power supply is well in excess of the 3A per 50 expected draw.

Previously I got around this by overvolting the 5v strings to about 5.8V at the power supply. This seems well within parameters for other scenarios, but it seems to be biting me some weeks later with....

  1. BrownING - yes! the casing (and it may be the filler waterproofing plastic they use) is actually going brownish... this seems bad and the lights are going greenish all down the line! Could this be a burnout chip early on degrading the signal further down the line??

I believe the driver is a lil arm chip if this helps.

PS: one thing people have talked about is using thin wires and inadvertently upping the resistance... mine are thin, but still multi-core and less than 4 meters.

PPS: I do use a lot of screw-down terminals is it possible that they have current limiting connections?

EDIT I have tried a short string and it lights up nicely..

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    \$\begingroup\$ 4 meters of 18awg stranded wire is maybe .25 ohms. If you are pulling the max expected 3A then the extra series impedance is dropping almost 1v. Fat wire is a must if you are feeding an entire string from a few meters away. You are likely over driving the leds at lower voltage and this is responsible for the damage to LEDS and casing as well as the inconsistent lighting \$\endgroup\$
    – crasic
    Commented Oct 13, 2015 at 7:04
  • \$\begingroup\$ The browning and failure of the LEDs is definitely due to over-voltage. Have you measured the voltage at the point of connection to the strip, rather than at the PSU? \$\endgroup\$
    – pjc50
    Commented Oct 13, 2015 at 9:35

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If possible, it might be better to add local (to the strip) switching regulator modules, then you can use low voltage 24V and not worry about wire size. Instead of 3A per strip you'll have more like 0.7A, and a volt or several volts drop will make no difference.

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