WS2801 LED strip - replace first LED

Using Arduino LEDs and Multiplexing
1

Hello,

I successfully installed my LED strip but unfortunately the first LED is not working properly (Blue is missing). So the plan was to cut it off and start with the second LED. However, after cutting it off and removing the heat-shrink tubing I realized, that there is one thing different than on the other LEDs. Between the inputs and the IC are two smd's (resistor?), with "470" on it.
Does anybody know what they are for and how to achieve this the best, so I won't kill my strip?

Thanks a lot
Jujup

2

They are there to terminate the signal and prevent electronic reflections.
Add external series resistors instead. 470 = 47 * 10^0 = 47 to the data and clock lines.
See page 13 of attached datasheet.
Confirm with a multimeter, use sharp probes to break thru any outer covering if needed.

WS2801.pdf (423 KB)

3

Thanks for the fast reply!

In the datasheet its said, I should connect a resistor at data input. But I guess it's one for data and one for clock?

4

Yes.

5

I'm not exactly sure about where to put the resistor. Are they connected to ground or just in the lines?

5V GND DATA CLK
| | | |
| | Ω Ω
| | | |
| | | |

or like this

5V CLK GND DATA
| | | |
| |-Ω-|--Ω--|
| | | |
| | | |

6

In series with the lines. Do not connect to ground.