LED Strip Issue: 3m (180 Diodes), 4 Sections, 12V 1.4A Power Adapter - Two Sections Not Working

Hello,
I have a problem with a 3m LED strip (180 diodes). I divided it into 4 equal sections, each connected in series with a 2x0.5mm² cable. After a few months, it turned out that two episodes suddenly stopped working. I use a 12V 1.4A power adapter

So you had 60 modules of 3 leds (each module 5cm long).
4 equal pieces of 15 modules.

each module (3 LEDs + resistor) is powered in parallel.

If one section consisting of a dozen or so modules is not lit, then check
is there voltage to it, maybe a cold solder ... sometimes a led or a resistor will fail in one module, but for all modules to fail you would have to connect a higher voltage.
Check that the power supply has 12V output

I corrected the contacts of the wire and tape once again with a soldering iron, but now they shine weaker, as if there was a voltage drop :/

Arek1255 wrote:

3m LED strip (180 diodes). I divided it into 4 equal parts

zbychmg wrote:

So you had 50 modules of 3 LEDs (each module 5cm long).
It cannot be divided into 4 equal pieces.

Some alternative math?
180/3=60 modules
60/4=15 modules per section
180/4=45 modules
Or maybe I'm counting something wrong, or I slept through important night shifts?

Thanks to e-sparks...

Well, actually, if the sun was still shining, I could explain that I was warmed up....

The night shift was too strong...

I fixed it, although I don't want to, but I have to...

Added after 11 [minutes]:

Maybe try cleaning the next solder contacts and connect the wires there,
or maybe replace the wires, I once bought such "copper" wires that the magnet attracted

Arek1255 wrote:

4 sections, each connected in series with a cable

And why in series, the tapes are probably 12V

Unless you connect the first module from the power supply, and from the end of this module the next module, as you described it in series, then the last module will actually have a lower voltage.

In this case, supply power to the last module with additional wires.
Or power 4 sections from the inside. If that doesn't help, bypass the power supply to the sections
parallel wire 0.5mm2

With one-sided power supply of a 5-meter tape (9W/m). The voltage drop on the copper tracks reached 1.5V V (I measured the voltage at the beginning of the tape and at its end).
They probably save on copper and the resistance of the power supply paths of individual modules is too high in relation to the supply current.

You did not specify the power of the W/m ruler and the distance from the power supply and between the sections.

0.5 mm2 wire is approx. 0.1 Ohm per meter. at a distance of 2m, it will be about 0.4 Ohm

If you can, take a meter and measure the voltage on the power supply of individual sections,
this is the best way to find the cause.....

zbychmg wrote:

Unless you connect the first module from the power supply, and from the end of this module the next module, as you described it in series, then the last module will actually have a lower voltage.

If a few months were shining well, then the resistance of the tracks in the tapes and wires did not suddenly increase?

@Arek1255 solder the wire between the last glowing and the first unlit section of the tape to the next pads, 3 diodes into the tapes.

Problem solved. Thank you for your help. I close the topic.