Bill Acceptor Keeps Rejecting Notes: A Field Troubleshooting Path

“It won’t take notes” is the single most common cash-acceptor complaint, and in most cases the fault is not the acceptor. Work the path below in order — cheapest causes first — and you will resolve the majority of cases on site without swapping hardware.

Stage 1 — Rule out the notes themselves

• Damp, heavily folded or taped notes fail even on clean optics. Test with a different strap of crisp, dry notes before touching the machine.
• Counterfeit-pen-marked notes can trip detection; try unmarked ones (official currency-authentication guidance from the U.S. Secret Service explains what marks mean).

Stage 2 — Optics and sensors

Dust on the optical path is the number-one real cause. Paper lint accumulates on the transparent sensors inside the throat. Use dry compressed air in short bursts through the note path; never wipe optics with a dry cloth — fibres scratch them.

Stage 3 — Transport path

• Listen: a note that starts to feed then stops usually indicates a worn rubber belt or a slipped roller — belt glazing shows as shiny, hardened rubber.
• Retrieve any jammed note with the release lever, power off first, and check the path for torn fragments left behind.

Stage 4 — Cassette seating and escrow behaviour

A cassette that is not fully seated keeps the unit from entering service mode. Confirm the cassette latch engages and the note-stacking area is not over-full. If the unit escrows then returns every note, the software state — not the hardware — may be rejecting the transaction; check the host machine logs.

Stage 5 — Interface and power

Intermittent acceptance followed by total silence often traces to marginal power: voltage sag during motor start will reset a module. Measure supply rails under load, inspect edge connectors for oxidation, and reseat ribbon cables before condemning the board.

If all five stages are clean and faults persist, the module genuinely needs bench repair. RMG keeps spares for the common validator families in stock, and our support desk can help match a tested replacement by interface and voltage rather than guesswork. Continue with the companion guides on matching a compatible acceptor spare and escrow versus drop behaviour, or browse everything in the RMG Knowledge Base.