When replacing FG4K-1000G-90G-NG, EncoderWorks configures the custom compatible replacement solution around 1000 PPR scaling, 0°/90° phase behavior, inverted signal pairs, N marker pulse repeatability, K radial terminal-box wiring, shielded twisted-pair transmission, and coupling preload. The main failure boundary is a system that appears electrically stable but calculates the wrong speed, reverses direction logic, or loses zero recovery because the pulse count, marker channel, or terminal assignment is not preserved. Typical production lead time: 15 working days.
This configuration belongs to the FG 4 optical incremental encoder platform for heavy-duty industrial environments. It uses 1000 pulses per revolution, square-wave output, a 0° basic channel, a second channel electrically shifted by 90°, inverted outputs for industrial signal transmission, and an N marker pulse with inverted marker signal. The K version uses a standard radial terminal box with terminal-strip wiring, not a redundant KK dual-terminal-box structure. Replacement work should focus on controller scaling, A/B phase sequence, N marker position, 100 kHz standard frequency margin, 150 kHz special-order boundary if applicable, shield bonding, cable-gland sealing, and shaft coupling alignment.
System Limits
The first system limit is 1000 PPR reference scaling. A controller set for 1024, 1200, 2000, 4096, or another pulse count may still receive clean A/B signals, but speed, length, travel, or synchronization values will be wrong. The counter mode, edge multiplication, speed conversion, and direction logic should be confirmed before startup.
The second limit is A/B/N signal behavior. The controller must receive A with /A, B with /B, and N with /N as paired signals. If the 90° phase sequence changes, direction can be interpreted incorrectly. If the N marker polarity, wiring, or mechanical reference position changes, homing and zero return may fail even though normal running looks acceptable.
The third limit is terminal-box EMC and mechanical preload. Long exposed shield drains, loose cable glands, moisture in the terminal box, or routing near inverter output, motor, brake, and contactor wiring can create false edges. Coupling misalignment, axial preload, radial load, or shaft shock can reduce bearing life and degrade pulse stability.
Wiring & Installation
Before replacement, record the radial terminal-box wiring for the basic channel, 90° channel, marker pulse, inverted signals, supply voltage, GND, shield, and LED-check or diagnostic output if used. Confirm that the controller is scaled for 1000 PPR and that the installed counter has enough frequency margin for the actual shaft speed and edge-counting mode.
During installation, fit the coupling smoothly and do not strike the shaft or housing. Keep the encoder centered, control angular and parallel offset, and avoid axial preload. Route A-/A, B-/B, and N-/N through paired shielded conductors, bond the shield through the terminal box with a short low-impedance path, and keep the signal cable away from high-current wiring. After commissioning, verify pulse count, speed scaling, direction, N marker repeatability, terminal-box sealing, and signal stability through the operating speed range.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed drive and counter system:
- Match 1000 PPR square-wave incremental output with 0°/90° channel behavior and inverted signal pairs
- Preserve N marker pulse behavior, K radial terminal-box layout, supply range, output level, and controller input compatibility
- Adapt the FG 4 mechanical envelope, shaft interface, flange or foot mounting requirement, coupling alignment, and cable-gland layout
- Review 100 kHz / 150 kHz frequency margin, shielded twisted-pair routing, EMC grounding, terminal-box sealing, bearing load, and marker-pulse repeatability
Key Data
| Item | Data |
|---|---|
| Model | FG4K-1000G-90G-NG |
| Encoder type | Heavy-duty optical incremental encoder |
| Series | FG 4 |
| Connection structure | K standard radial terminal box |
| Pulses per revolution | 1000 PPR |
| Pulse disk class | Nickel-disk available pulse rate |
| Signal output | Square wave, 0° and 90° channels |
| Inverted signals | Yes, Option G |
| Marker pulse | Option N with inverted marker signal |
| Supply voltage | 12–30 VDC |
| Output type | Differential line driver / push-pull style output |
| Frequency range | 0–100 kHz standard, up to 150 kHz if specified |
| Standard shaft | Ø11j6 × 30 mm |
| Optional shaft | Ø14j6 × 30 mm |
| Key checks | 1000 PPR scaling, A/B phase sequence, N marker, terminal-box shielding, coupling preload |
