If you have no audio output, the common culprits include:

Red Screen Boot (Atari Jaguar)

Audio Circuit (Atari Jaguar)

Video Output (Atari Jaguar)

RetroSix Wiki

Byte Swapping (BIOS Files)

Digital Logic Levels

YUV vs YCbCr vs RGB (Color Space)

RGB Formats

Composite (CVBS)

S-Video (Y/C)

Component (YPbPr)

VGA (RGBHV)

SCART

CleanRGB SCART Cables

Learn Electronics

Power Supply Details

PC Floppy Drive In Amiga

Create Amiga Floppy Disk On PC

Amiga (Various)

Schematics (Amiga 600)

Power Circuit (Amiga 600)

No Screen (Amiga 600)

White Screen (Amiga 600)

Amiga 600

Schematics (Atari 2600)

Hardware Overview (Atari 2600)

Joysticks (Atari 2600)

TIA Chip (Atari 2600)

Video / Button Hex Buffer (Atari 2600)

Extracting Composite Video (Atari 2600)

TIA Video Faults (Atari 2600)

Atari 2600

Schematics (Atari 7800)

Hardare Overview (Atari 7800)

Video Output (Atari 7800)

Atari 7800

Schematics (Atari Jaguar)

Power Circuit (Atari Jaguar)

BIOS Boot (Atari Jaguar)

Black Screen (Atari Jaguar)

Tom IC (Atari Jaguar)

UART JagLink (Atari Jaguar)

Region Free BIOS (Jaguar)

Atari Jaguar

Schematics (Atari Lynx)

Safe Boot (Atari Lynx)

Power Circuit (Atari Lynx)

The Mikey ASIC (Atari Lynx)

Atari Lynx

Schematics (Atari Lynx II)

Board Scans (Atari Lynx II)

Safe Boot (Atari Lynx II)

Power Circuit (Atari Lynx II)

The Suzy ASIC (Atari Lynx II)

The Hayato ASIC (Atari Lynx II)

LCD Circuit (Atari Lynx II)

LCD Interface (Atari Lynx II)

LCD Enable Pin (Atari Lynx II)

Reading Game Cartridge (Atari Lynx II)

Hayato / Mickey / Suzy Variations (Atari Lynx II)

Atari Lynx II

Schematics (Commodore 16)

Power Circuit (Commodore 16)

CPU 8501 (C16)

Commodore 16

Schematics (Commodore 64)

Commodore 64

Schematics (Dreamcast)

Region Free BIOS (Dreamcast)

Region Change (Dreamcast)

Minimum Boot (Dreamcast)

Dreamcast

GB CleanAmp Install Guide

GB CleanPower Install Guide

Game Boy

GBP IPS Screen Install

GBP CleanAmp Install Guide

Game Boy Pocket

GBC IPS Screen Install

GBC Board Scans

GBC CleanAmp Install Guide

Schematics (Game Boy Advance)

Board Scans (Game Boy Advance)

Dehum Dehiss: Removing noise from GBA audio

Power Regulator Circuit (Game Boy Advance)

Power Switch Circuit (Game Boy Advance)

Wire Free Dehum Kit (Game Boy Advance)

CleanAmp Install Guide (Game Boy Advance)

LED Triggers (Game Boy Advance)

GBA-SP Board Scans

Dehum Dehiss: Removing audio noise from GBA SP

Battery Charge Circuit (GBA SP)

USB-C Charging (GBA SP)

GBA-SP CleanAmp Install Guide

Game Boy Advance SP

Schematics (Game Gear)

 Board Scans (Game Gear)

Hardware Overview (Game Gear)

Model Versions (Game Gear)

Soft Start / Fast Reset (Game Gear)

Getting to Red Light Boot (Game Gear)

ASIC Dead Test (Game Gear)

Reading Game Cartridge (Game Gear)

LCD Circuit (Game Gear)

Visual Diagnostics (Game Gear)

VA0/VA1 LCD Interface (Game Gear)

CleanScreen Installation Guide (Game Gear)

Capacitor Replacement (Game Gear)

Power Circuit (Intellivision)

RF Module (Intellivision)

Mattel Intellivision

Schematics (Neo Geo AES)

AV Pinout (Neo Geo AES)

Initial Power Up (Neo Geo AES)

Diagnostic BIOS (Neo Geo AES)

Visual Diagnostics (Neo Geo AES)

RGB Video Out (Neo Geo AES)

Video Encoder (Neo Geo AES)

Fixing RGB Voltages (Neo Geo AES)

Neo Geo AES

Power Circuit (Panasonic Q)

Ribbon Connections (Panasonic Q)

Power Up Basics (Panasonic Q)

Panasonic Q

Schematics (PC Engine)

Board Scans (PC Engine)

Visual Diagnostics (PC Engine)

PC Engine

AV Pinout (PC Engine Duo-R)

RGB Video Output (PC Engine Duo)

PC Engine Duo

Schematics (PC Engine GT)

Board Scans (PC Engine GT)

Expected Power Draws (PC Engine GT)

Front Button Board (PC Engine GT)

5V Circuit (PC Engine GT)

Backlight Driver (PC Engine GT)

LCD Circuit (PC Engine GT)

Audio Circuit (PC Engine GT)

PC Engine GT

Laser Tuning (PS2)

PlayStation 2

PS5 HDMI Port

Playstation 5

SNES Controller Board Scans

PPU Chips (SNES)

AV Pinout (Master System)

Master System

Hardware Overview (Mega CD)

Power Circuit (Sega Mega CD)

Boot Up Diagnostics (Mega CD)

Mega CD Engine Pinout

Region Free BIOS (Sega Mega CD)

Sega Mega CD

Schematics (Sega Mega CD 2)

Board Scans (Sega Mega CD 2)

Sega Mega CD 2

Hardware Overview (Sega Mega Drive)

AV Pinout (Sega Mega Drive)

Sega Mega Drive

AV Pinout (Sega Mega Drive 2)

Sega Mega Drive 2

Schematics (Sega Mega-Tech)

Hardware Overview (Sega Mega-Tech)

Powering From Bench (Sega Mega-Tech)

Menu Select BIOS (Sega Mega Tech)

Mega Drive (Sega Mega-Tech)

Sega Mega Tech Arcade

Power Basics (Multi Mega)

Laser Tuning (Multi Mega)

Hardware Overview (Sega NAOMI 2)

Power Rails (Sega NAOMI 2)

No Screen (Sega NAOMI 2)

Black Screen (Sega NAOMI 2)

Glitched Graphics (Sega NAOMI 2)

Sega Naomi

Region Free BIOS (Sega Saturn) (cloned)

Sega Saturn Minimum Boot

Laser Tuning (Sega Saturn)

Sega Saturn

Board Scans (Nintendo Switch)

First Stage Boot Short Checks

3.3V Regulator Checks

Full Boot from Bench Power

BQ24193 Battery Charger

Diagnostics Power Draws

MAX77620 CPU Regulator

eMMC Booting

Joy Cons (Nintendo Switch)

Nintendo Switch

Power Up Basics (Xbox Original)

System Management Controller (Xbox Original)

Power Supply Pinout (Xbox Original)

AV Cable (Xbox Original)

Flashing Orange LED (Xbox Original)

DVD Drive (Xbox Original)

Xbox Original

White Light Diagnosis (Xbox One S)

Hard Drive Offline System Setup (Xbox One S)

HDMI Issues (Xbox One S)

Repair & Schematics