Royal 660-9 Encoder Replacement Module

Problem

The personally owned Royal 660-9 depended on a difficult-to-source vend-position feedback assembly. Replacing the whole mechanism was wasteful; the real need was a dependable module that could recognize movement and home position while the original controller continued to drive the motor.

Description

What I built or investigated

I inspected the Royal 660-9 motor-mounted feedback hardware, identified the separate motor and sensor conductors, tapped the feedback channels, and built Arduino-side logic to observe the channel states and reconstruct a repeatable vend/home sequence.

Iterations

The work did not happen in one jump.

1. 01

   Confirmed that the vending controller powered the motor while the attached sensor assembly only reported position.

2. 02

   Identified and tapped the existing feedback conductors without relying on the motor-power wires.

3. 03

   Read the two feedback channels as changing A/B states during movement.

4. 04

   Used the observed sequence and timing to distinguish motion from the home/end position.

5. 05

   Moved the concept toward a dependable replacement module rather than a one-off external timer.

Result

Where the project landed

A bench-tested foundation for replacing the Royal 660-9’s obsolete position-feedback assembly while preserving the existing motor and vend mechanism.

Lessons

What carried forward

• The most useful repair often replaces the unavailable subassembly, not the entire system.
• Power and feedback must be understood as separate signal paths before reverse engineering begins.
• A repeatable state sequence is more reliable than timing the motor alone.

Images & evidence

Work in context