Every pre-soldered Zega Mame Boy is fully tested prior to shipping including: All inputs, Audio (headphone and speaker, Video & Power supply. If you do encounter any issue please DO NOT CHANGE SOFTWARE SETTINGS. If you have already altered any settings or updated Retropie in any way, install a fresh copy of the image before contacting me.
As stupid as this sounds, a number of customers have been using a Pi Zero, mistakenly thinking it to be a Zero 2. This is actually not that stupid. If you are not familiar with the Raspberry Pi Zero it can be easy to mistake one for the other. If in doubt, ask me first and I can confirm which model you have.
This can happen for a number of reasons.