Chosen Solution

I have an early 2015 MacBook retina a1534 that I just repaired the c-port and replaced some ribbons and the touchpad. Everything is working fine, except the internal speakers. I can plug in headphones and get audio, just nothing through the internal speakers. Internal speakers do show up as an output device. I’ve tried the most common solutions:

  1. NVRAM and SCM resets, 2) Created new user, 3) Reseated audio board ribbon cable. My question is could a damaged audio board and/or ribbon cable affect the internal speakers, even though the headphone output is working properly? Thanks in advance for any insight on this odd issue

The fact you are getting sound via the headphone jack removes everything but the auto board its self! Let me explain… The action of plugging in your headphone plug into the jack causes two switches within it to alter their state as you can see here

So what’s happing is the closed circuit which sends the signal to the speakers is not happening. Check your headphone plugs as you may be using one that cause the damage or its just dirty. More often I find I need to replace it MacBook 12" Retina (Early 2015-2017) Audio Board

Either the connector is damaged, the audio circuit is blown or the speakers are dead.