Magnetic and pulse attacks are a specific, hardware-level way of cheating the coin mechanism. Both have the same goal — make the machine count credits that were never paid for — but they hit different parts of the coin path: a magnet interferes with the mechanical or sensor side of the acceptor, while a pulse attack feeds a false "coin in" electrical signal toward the board. They are popular with cheaters because they are quick, need no software, and on older or poorly protected cabinets they work. They are also, fortunately, among the most detectable once you understand the coin path.
I have repaired and hardened coin mechanisms for fourteen years in Panyu, Guangzhou. This page tells you what these attacks look like and how to catch them — not how to carry them out.
A genuine credit happens in two stages. First, the acceptor validates a coin or token using mechanical sizing and electromagnetic sensing. Then it sends a short electrical pulse down a wire, and the board counts that pulse as one credit. Magnetic and pulse attacks each target one of those stages:
Magnetic attacks go after the validation stage — the sensing that decides whether something is a real coin and how it moves through the mechanism.
Pulse attacks go after the signalling stage — the credit pulse the board listens for.
Knowing this split is the whole game, because the defence is the same in both cases: watch the coin path for events that do not match a real, paid coin.
I will keep this at recognition level. A magnetic approach tries to fool or disturb the acceptor's sensing so the mechanism behaves as if a valid coin passed when it did not, or so it miscounts. The tells:
A coin acceptor that suddenly registers credits inconsistently, or counts more than the coins actually inserted.
Faint scratch marks or residue around the validation area of the acceptor.
An acceptor that starts misbehaving only intermittently — fine most of the day, generous in a particular window.
Modern, well-built acceptors resist this far better than old ones, which is part of why grey-market and ageing cabinets get targeted.
A pulse attack bypasses validation entirely and aims a false credit pulse at the board. Because it skips the coin, it is fast and can rack up credits with no cash at all — it is the wiring cousin of coin acceptor and wiring tampering and of score theft more broadly. The tells:
Credit counts that climb with little or no matching cash — the classic cash-to-meter mismatch, often appearing in sudden blocks.
A credit wire that shows fresh strip marks, a tap, or tape that was not there before.
A connector on the coin harness that has been unseated and reseated.
Sudden large credit jumps in a second or two — no human inserts coins that fast.
The honest difficulty is timing. A magnet attack can leave almost no permanent mark, and a pulse attack happens in a flash during a quiet moment. A physical inspection at the next collection might show something, but it will not tell you when it happened, how often, or who was at the cabinet. You need something watching the coin path continuously.
The practical answer is a detection unit at the cabinet that recognises abnormal coin-path events the instant they occur, alarms, and logs them.
A Score Theft Detection Unit does exactly this. Set beside or under the cabinet — no wiring, no need to open the harness — it monitors for the abnormal credit behaviour these attacks create: false pulses, abnormal credit jumps, and the disturbance that comes with interfering with the acceptor or its wiring. The moment it sees one, it alerts and saves a time-stamped record. Gen 1 covers a single cabinet at about 1–1.5 m; Gen 2 reaches 2.5–3 m for a tight cluster. Both run on 220V, draw under 5W standby, sit in a flame-retardant ABS case roughly 12×8×5 cm, and do not affect normal play. The log is what turns "the count is off again" into "the coin path on cabinet two was hit three times this week, here are the timestamps" — and a pattern is what lets you act. How the unit separates a real attack from honest coin-in is explained in how arcade anti-cheat detection devices work.
Harden physically as well: replace weak or old acceptors with better-shielded units, upgrade flimsy coin-door locks, route credit wiring out of easy reach, and inspect the coin path on every collection. The early signs that this is happening are in why my arcade machine accounts do not add up, and the attack sits within the full picture at how arcade machine cheating actually works.
If your coin counts keep outrunning the cash, send me your cabinet and acceptor models on WhatsApp or WeChat at +86 17620842078 and I will tell you which unit covers them and how to place it. My team is also on the contact page.
— Engineer Wang