LED strip fault-tracing

[blackdogsdad]

I bought a 4500mm LED strip roll complete with power supply and I've cut this into 5x800mm and 1x500mm lengths.
I've used proprietary connectors to join the strips back together on my project but have had to solder additional lengths of wires
between the connectors as the wires attached to the connectors were not quite long enough.
All strips lit up fine until I attached the final 500mm length: this one was usually not as bright as the others
and would also blink on and off.
I then tried connecting the power-supply to the 500mm strip and sending the power back through the strip
assembly "in the opposite direction": this time the 500mm strip works fine as do all of the 800mm strips apart from the last one
in the run which has now become the dimmer one and sometimes flashes off and on.
Does anybody know why this is happening?
Might it be my soldering?
Or should I scrap the lot, buy new parts and try again?!?
(Incidentally, the uncut 4500mm strip worked fine.)

 

[bertus]

Hello,

Did you cut the strip on the correct position?
Here is an example of a RGB ledstrip:

Bertus

 

[Harald Kapp]

What kind of LED strip?
- single color?
- RGB?
- addressable (WS2812 or similar)?

In any case: the traces on such an LED strip are comparatively highly resistive. The voltage will drop along the length of the strip due to the current drawn by the LEDs along the strip. It may be required to supply additional power through sutable wires (e.g. 0.5 mm²) after e.g. 1/2 of the length of the strip.

With single color LED strips or addressable LED strips, simply connect an additional power feed ("+" and "-") after about 1/2 of the total length. Or supply power from both ends. With addressable LED strip do not (!) feed the data signal anwhre else but to teh beginning of teh strip.
With RGB LED strips you need to supply all 4 connections (R, G, B and +5 V) either after 1/2 of the total length or from both sides.

 

[blackdogsdad]

Hello,

Did you cut the strip on the correct position?
Here is an example of a RGB ledstrip:
View attachment 63382
Bertus

Hello bertus!
Thanks for your reply: yes I cut the strips in exactly the correct positions.

 

[blackdogsdad]

What kind of LED strip?
- single color?
- RGB?
- addressable (WS2812 or similar)?

In any case: the traces on such an LED strip are comparatively highly resistive. The voltage will drop along the length of the strip due to the current drawn by the LEDs along the strip. It may be required to supply additional power through sutable wires (e.g. 0.5 mm²) after e.g. 1/2 of the length of the strip.

With single color LED strips or addressable LED strips, simply connect an additional power feed ("+" and "-") after about 1/2 of the total length. Or supply power from both ends. With addressable LED strip do not (!) feed the data signal anwhre else but to teh beginning of teh strip.
With RGB LED strips you need to supply all 4 connections (R, G, B and +5 V) either after 1/2 of the total length or from both sides.

Hello Harald,
Thanks for your prompt reply.
They're single-colour (white) although I'm very much an amateur so unfortunately don't know what WS2812 or addressable means.
The description (on ebay) was "12V Cool White Led Strip Light 3528 SMD 60leds/m"
Anyhow, are you saying that if I purchase a second power supply and basically split my LED project into two separate runs that should work?
Thanks again and please pardon my ignorance!

 

[Harald Kapp]

No need to buy a second power supply. You use the one you have. Like so:


To the left is your power supply. You connect the output of the power supply at both ends of the LED strip.
Watch out to connect "+" to "+" and "-" to "-" !
Of course you could also split the LED strip into 2 parts, but that is not necessary.

 

[blackdogsdad]

No need to buy a second power supply. You use the one you have. Like so:
View attachment 63383

To the left is your power supply. You connect the output of the power supply at both ends of the LED strip.
Watch out to connect "+" to "+" and "-" to "-" !
Of course you could also split the LED strip into 2 parts, but that is not necessary.

Thanks again Harald! I'll try that shortly... I would NEVER have thought of doing this!!! (Sorry for the delayed reply)

 

[blackdogsdad]

Done it and it works with not a hint of a flicker anywhere!!! You knew it would work of course but anyway, I'm VERY happy. Thank you so much for the advice.