Classic Arcade Power Supplies Explained: +5V, +12V, Ground, and Voltage Drop

By HighScoreSaves Technical Team

Reviewed and updated August 23, 2026

Every original arcade PCB requires the correct electrical power to operate. The cabinet power system must provide the voltages required by the game and deliver them through wiring, connectors, and PCB contacts with the correct polarity and a reliable ground path.

Two voltage rails commonly encountered on classic arcade hardware are +5 volts and +12 volts, although the exact requirements vary by game and hardware platform. Older and specialized systems may require additional voltages.

Understanding power, ground, connector resistance, and voltage drop helps explain why an arcade PCB can behave differently when measured at the power supply versus at the board itself—and why increasing a voltage adjustment without understanding the actual problem can damage vintage hardware.

What Does an Arcade Power Supply Do?

An arcade cabinet receives AC mains power, but the game PCB generally operates from regulated DC supply voltages. The cabinet's power system converts and distributes the electrical power required by its components.

Depending on the cabinet and era, the power system may involve a linear supply, switching power supply, transformer assembly, rectification and regulation circuitry, or a combination of components.

Because classic arcade hardware varies widely, the correct schematic or service documentation should be consulted before assuming the required voltages or connections.

What Is +5V Used for on an Arcade PCB?

On many classic arcade PCBs, the +5V rail supplies much of the digital logic. CPUs, RAM, ROM interfaces, logic ICs, and other digital circuitry commonly depend on a properly regulated supply.

This makes the +5V supply particularly important. If the voltage reaching the PCB is outside the acceptable range for the hardware, the game may operate incorrectly or fail to operate at all.

The correct voltage and acceptable tolerance are hardware-specific. Do not assume that every board should be adjusted to exactly the same measurement without consulting the proper documentation.

What Is +12V Used for?

+12V is another common arcade supply rail, but its purpose varies by design. It may be used by audio circuitry, amplifiers, certain analog circuits, coin-related hardware, or other devices.

Some boards and cabinet components use additional positive or negative voltages as well. Pre-JAMMA arcade hardware in particular should never be treated as though it automatically follows later JAMMA power conventions.

The PCB pinout and cabinet documentation should determine what power belongs on each connection.

Why Is Ground Important?

Voltage only makes sense relative to a reference. In the arcade PCB's DC power system, ground provides the common reference and return path used by the circuitry.

A poor ground connection can therefore create serious operating problems even when the power supply itself appears to be producing the expected voltage.

Ground connections should not be confused with every other grounding or safety-earth connection found inside a cabinet. Cabinet wiring and electrical safety should be understood from the correct documentation before modifications are made.

What Is Voltage Drop?

Wiring and connections have resistance. When electrical current flows through resistance, some voltage can be lost between the source and the load.

In an arcade cabinet, the electrical path between the power supply and PCB may include wiring, crimp terminals, plugs, harness contacts, adapters, and PCB edge fingers. Age, oxidation, contamination, heat damage, loose contacts, and poor repairs can increase resistance.

The result can be a higher voltage measured at the supply terminals and a lower voltage actually reaching the arcade PCB.

Why Does Voltage at the PCB Matter?

The game circuitry operates from the voltage that actually reaches the PCB, not simply the voltage present at the output terminals of the power supply.

If there is significant resistance in the wiring or connector path, measuring only at the supply can hide the voltage loss occurring between the supply and the board.

This is one reason the condition of the cabinet harness and PCB connector matters when evaluating power-related problems.

Edge Connectors Can Affect Power Delivery

Many original arcade PCBs receive power through conductive fingers at the board edge. The mating harness connector presses contacts against those fingers.

Dirty, oxidized, loose, worn, or heat-damaged connections can increase resistance. Power contacts carrying substantial current are especially important to inspect when there is visible discoloration or connector damage.

Learn how these connections work in Arcade Edge Connectors Explained: Dedicated PCB Connectors, JAMMA, and Adapters .

JAMMA Standardized Common Power Connections

JAMMA standardized a common arcade PCB interface that includes established positions for power, ground, video, audio, controls, and other functions.

That standardization made compatible board changes easier, but it does not mean all arcade hardware uses JAMMA. Many classic games use dedicated pre-JAMMA wiring, and later systems may require additional connections beyond the basic standard.

See What Is a JAMMA Arcade PCB? JAMMA vs. Pre-JAMMA Classic Arcade Hardware before assuming a board follows JAMMA power connections.

Why Turning Up the Power Supply Is Not Automatically the Solution

If voltage reaching a PCB is low because of excessive resistance in a connector or wiring path, simply increasing the power-supply adjustment does not repair the bad connection.

Raising the source voltage can also create excessive voltage if the load changes, a poor connection is later repaired, or another board is connected.

Vintage integrated circuits can be damaged by improper supply voltage. Determine why the measurement is incorrect rather than treating the adjustment control as a universal repair.

Can Low Voltage Cause an Arcade Game Not to Boot?

Incorrect power can contribute to startup failures, unstable operation, resets, corrupted behavior, or other problems. However, those symptoms are not unique to the power supply.

CPU orientation, daughterboard seating, damaged sockets, bent pins, ROM changes, wiring errors, and unrelated PCB faults can also prevent a game from operating correctly.

If a game stops working immediately after an upgrade installation, follow Arcade Game Won’t Boot After Installing an Upgrade Kit: What to Check First before changing unrelated adjustments.

Never Assume an Unknown Arcade PCB Pinout

Applying the wrong voltage to the wrong PCB contact can damage original hardware. This is especially important with dedicated pre-JAMMA boards, conversions, bootlegs, reproductions, and unfamiliar adapters.

Physical connector fit does not prove electrical compatibility. Identify the board and verify its pinout before connecting power.

Use How to Identify Your Original Arcade PCB Before Ordering a Kit when the hardware inside a cabinet is uncertain.

Document Wiring Before Removing a PCB

Before disconnecting an original arcade board, photograph its wiring, edge connector, separate power plugs, grounding wires, adapters, and connector orientation.

Decades-old cabinets may have undocumented modifications or repairs. Photographs provide a reference if the actual cabinet differs from a factory diagram.

See How to Safely Remove and Reinstall an Original Arcade PCB for the complete handling procedure.

Correct Power Begins With the Correct Hardware Information

+5V, +12V, ground, and other supply connections are fundamental to arcade operation, but the exact requirements must come from the hardware being serviced.

Measure and evaluate the complete electrical path rather than assuming the power supply itself is the only part that matters. Wiring, connectors, adapters, edge contacts, and previous repairs can all affect the voltage reaching the PCB.

Most importantly, never compensate for an unknown problem by increasing voltage without first understanding the board, its required supply, and the condition of the connections delivering that power.

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