UdaraVimarsha said:

I add Jspk2 port and two resistors to aspire 5742z  from aspire 5733z, but both L and R channel coming from both speakers(still MONO), can you please help me with that?

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I noticed that the second speaker doesn't respond to volume controller. So after going through schematic stuff I just simply unsolder J1 Jumper (1.5v_1). still I don't understand well what's the J1 jumper for, But it worked.

Thank You!

JackE said:

The 5742z realtek audio interface was set up to be monophonic, not stereophonic. Jack E/NJ

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Acer aspire 5733z and acer aspire 5742z has same schematic (PEW71 LA-6582P ::Rev 1.0) and It should be same BIOS, There's only some feature components  goes up and down (ex: 5733Z has no HDMI and  Bluetooth)

So not missing features, Just missing components (Not all Some are drop and add with the version [Rev 0.2, 1.0]) 
          P.S.  And aspire 5733z realtek audio drivers don't work well with both speakers, It make a mess

I don't understand what is the differences between acer aspire 5733, 5733z, 5742, 5742z yet. If both models use Same PEW71 LA-6582p  schematic board, only difference I see is the BIOS, HDMI and Bluetooth. 
When I solder jspk2 and two resistors to aspire 5742, Realtek audio drivers doesn't support for second speaker (I tried both aspire 5742 and 5733 drivers Audio_Realtek_6.0.1.6564_Win8x86x64 and Audio_REALTEK_6.0.1.6141_Win7x86x64). It just clones two internal speaker ports and both Right int. Speaker and right HD (Headphone Jack) doesn't respond to the volume controlling (except for mute which controls by shutdown pin of U37)

But I uninstall Realtek and install default Microsoft high definition audio driver. now it is working as it supposed to be, working well.

Please help me to understand this.

sincerely,

Udara Vimarsha.