Arcade Video Signals Explained: RGB, Sync, and How the PCB Connects to the Monitor

By HighScoreSaves Technical Team

Reviewed and updated August 23, 2026

The image on a classic arcade monitor begins with the game hardware. The arcade PCB generates video information and sends electrical signals through the cabinet wiring to a compatible monitor, where those signals become the picture seen by the player.

Many classic raster arcade systems use separate red, green, and blue video signals together with synchronization information. These are commonly described as RGB and sync.

Understanding that signal path helps explain the relationship between the PCB, edge connector or harness, cabinet wiring, and monitor—and why a bad picture does not automatically mean the monitor itself is defective.

How Does an Arcade PCB Create the Picture?

A classic arcade PCB contains circuitry responsible for producing the game's visual output. The exact architecture varies by game, but it can involve graphics ROMs, RAM, counters, custom chips, logic circuitry, color circuitry, and other components.

The stored graphics data is only part of the process. The video hardware must determine what should appear on the screen, where it should appear, what colors should be used, and when the monitor should draw each part of the image.

For background on the stored data used by arcade hardware, see Original Arcade ROMs Explained: Program ROMs, Graphics ROMs, and Sound ROMs .

What Does RGB Mean?

RGB stands for red, green, and blue. These are the three color components commonly used by classic raster arcade video systems to create the colors displayed on the monitor.

Rather than sending one combined consumer-video signal, many arcade PCBs provide separate electrical signals for red, green, and blue.

By varying the intensity of those components, the monitor can display the colors required by the game.

RGB is therefore describing the video signal components between the game hardware and monitor; it is not the same thing as the graphics data stored in a ROM.

What Is Arcade Video Sync?

The monitor also needs timing information so it knows when to begin and coordinate the drawing of the image. This timing information is provided by synchronization signals, commonly called sync.

Depending on the hardware, synchronization may be provided in different forms. Some systems provide composite sync, while others may use separate horizontal and vertical synchronization signals or other arrangements.

The arcade PCB and monitor must be electrically and operationally compatible with the video and synchronization signals being used.

What Happens If Sync Is Incorrect?

When the monitor cannot properly lock onto the synchronization information, the picture may fail to stabilize.

Depending on the monitor and the nature of the signal problem, symptoms can include rolling, tearing, an unstable image, incorrect positioning, or failure to display a usable picture.

These symptoms do not by themselves prove whether the fault is in the monitor, PCB, wiring, connector, adapter, or adjustment. The complete signal path must be considered.

How Does Video Travel From the PCB to the Monitor?

The video signals leave the game PCB through its designated connections. On many boards, those connections are part of the main PCB edge connector. Other hardware may use separate plugs or additional connectors.

The cabinet harness carries the signals from the PCB toward the monitor. Depending on the cabinet and monitor, the wiring then terminates at the appropriate video input connections.

A poor connector, broken wire, incorrect adapter, damaged PCB finger, or wiring modification anywhere in that path can interfere with video even when both the PCB and monitor are otherwise functional.

How Does JAMMA Carry Video?

JAMMA standardized common connection positions for red, green, blue, video sync, and video ground along with power, audio, controls, coin inputs, and other functions.

This made it easier for compatible JAMMA game boards to connect to cabinets using the same standard harness.

For the broader interface explanation, read What Is a JAMMA Arcade PCB? JAMMA vs. Pre-JAMMA Classic Arcade Hardware .

Pre-JAMMA Video Wiring Can Be Different

Earlier dedicated arcade hardware did not share one universal connector arrangement. Manufacturers could place video signals wherever their particular board and cabinet design required.

A connector that physically fits another board does not establish that red, green, blue, sync, ground, or power occupy compatible positions.

Always identify the PCB and verify the documented pinout before connecting unfamiliar hardware.

What Does an Arcade Wiring Adapter Do With Video?

An adapter can route video signals from the positions used by one PCB connection arrangement to the appropriate positions required by another harness or test setup.

For example, an appropriately designed adapter can route a dedicated pre-JAMMA board's video outputs to the corresponding connections used by a JAMMA-based setup.

The adapter does not convert the original game PCB into a JAMMA PCB. It provides an electrical interface between different connector arrangements.

This distinction is covered further in Arcade Edge Connectors Explained: Dedicated PCB Connectors, JAMMA, and Adapters .

Is Every Arcade Monitor Compatible With Every Arcade PCB?

No. Arcade monitors and game boards were produced with different signal requirements, scanning characteristics, synchronization arrangements, orientations, and other electrical considerations.

A monitor physically fitting inside a cabinet does not establish signal compatibility with the PCB. Likewise, an adapter that changes connector pinout does not necessarily convert one video format into another.

Verify the specifications and documentation for both the game hardware and monitor before connecting unfamiliar equipment.

Horizontal and Vertical Arcade Games

Classic arcade monitors may be physically installed in a horizontal or vertical orientation depending on the game.

Monitor orientation is separate from the RGB and synchronization signals themselves. A PCB designed for a vertically oriented game can still generate conventional arcade RGB video; the cabinet simply positions the monitor appropriately for the intended image.

Orientation becomes especially important with multigame systems because the included games must make sense for the monitor and cabinet configuration being used.

Multigame Kits Still Use the Original Hardware's Video System

A HighScoreSaves multigame upgrade for a supported original arcade PCB does not turn the cabinet into a generic emulation system with an unrelated video interface.

The supported original arcade hardware remains the foundation of the game system. That means cabinet controls, monitor orientation, original PCB compatibility, and the hardware platform's video capabilities remain important considerations.

Learn more in How Multigame Upgrade Kits Work on Original Arcade PCBs .

A Bad Picture Does Not Automatically Mean a Bad Monitor

The monitor is only the final major part of the video path. A video problem can begin before the signal ever reaches it.

Depending on the symptom and hardware, possible areas to investigate can include the PCB's video circuitry, RAM, ROM or graphics circuitry, edge connector, harness, adapter, ground, sync wiring, monitor input, or the monitor itself.

Avoid changing several things simultaneously. A controlled troubleshooting process makes it much easier to determine which change affects the symptom.

If a problem began immediately after installing an upgrade, use Arcade Game Won’t Boot After Installing an Upgrade Kit: What to Check First as the starting point rather than immediately adjusting the monitor.

Document Video Connections Before Removing the PCB

Before removing unfamiliar original arcade hardware, photograph all connectors and wiring. This is particularly useful when a cabinet contains separate video plugs, adapters, conversion wiring, or undocumented modifications.

Connector orientation should also be documented. Reversing an unknown edge connector or plug can route signals—and potentially power—to incorrect locations.

Follow the handling process in How to Safely Remove and Reinstall an Original Arcade PCB .

The Video Path Extends From the PCB to the Screen

A classic arcade picture is the result of an entire signal path. The PCB generates the video, the connector and cabinet harness carry it, and the monitor converts those electrical signals into the image seen by the player.

RGB provides the color information, while synchronization tells the monitor how to coordinate the image. Both must reach compatible hardware correctly.

Understanding that complete path makes it easier to identify original arcade hardware, interpret wiring diagrams, use adapters correctly, and avoid assuming every display problem originates inside the monitor.

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