Audio 2.1 Speakers+Subwoofer, one speaker not outputting audio

Hi, hope you guys can help/guide me out.

So I receive a gift a couple of months ago, but did not have the chance to test it until now.

I have a set of audio speakers+sub-woofer, if you take a look at the pics (specially the back.jpg) the speakers are connected through a RCA cable, and where says input its a 3.5mm cable that goes into the computer (speakers output)

Now when I connected them to the PC, the sub-woofer and right speakers works fine, but the left is not producing audio at all. I find out that both speakers are working fine if I connected them in the red output/R, seems the left one is not working. At first I thought it was config of my PC I did download the latest drivers from Realtek Website, I tried the ones that comes from the DVD/Motherboard (ASROCK H81M-HDS) and same issue. I tried multiple settings from the audio devices (5.1 surround, quadraphonic, stereo) but no success.

Finally what I did is that I connected the system to my Galaxy S3 smartphone and another audio system as well and I have the same issue, no audio coming from the output Left/White, Subwoofer is working fine, and output/Red(Right) is working fine. I'm not sure if its due to the fact that system receives the signal from a 3.5mm cable and then has to send it through 3 outputs (L/R RCA speakers and the subwoofer)

What I'm trying to find out is, if this something related to the audio system itself, or does the PC and S3 need a configuration?
In case is something related (hardware) of the audio system, could it be repairable?

thanks in advance!

As the speakers do the same thing on two different systems it says there is a problem with the speaker system. I see RCA connectors on the rear for the two speakers. Switch the connections (connect the right speaker to the Left jack and the left speaker to the right jack) and see if it follows the speaker or if its the Left output from the speaker base. That will isolate where the problem is. If its the speaker base unit, the problem could be the cable that connects to the PC or it could be an internal amplifier problem. However, in either case if the speaker system is still under warranty, contact the manufacturer for warranty assistance.

In most cases these are not made to be repaired, but I see screws holding the back on, the base unit, and you may be able to get into the electronics. However, without a schematic you are probably not going to find any problems.