FG4K-1024G-90G-NG should be replaced as a preferred nickel-disk FG 4 feedback encoder, where EncoderWorks can configure a custom compatible replacement solution around the 1024 PPR scaling, 0°/90° channel relationship, inverted signal pairs, N marker pulse, K radial terminal-box wiring, shielded twisted-pair transmission, and coupling preload. The main failure boundary is not high-frequency overload, but wrong scaling, reversed phase sequence, marker-pulse mismatch, or poor terminal-box shielding after replacement. 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 1024 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 accuracy, N marker alignment, 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 1024 PPR scaling. If the drive or PLC was configured for 1000, 1200, 2000, 4096, or 5000 PPR, speed and travel values will be wrong even when the encoder outputs are electrically stable. Edge-counting mode, direction detection, and speed conversion must be verified before startup.
The second limit is phase and marker behavior. The controller must receive A with /A, B with /B, and N with /N as stable paired signals. If the 90° phase sequence is reversed, direction can be interpreted incorrectly; if the N marker polarity, timing, or terminal assignment changes, homing and zero recovery can fail.
The third limit is terminal-box EMC and coupling load. Long exposed shield drains, loose cable glands, moisture in the terminal box, or cable routing close to inverter and motor wiring can introduce false edges. Coupling misalignment, axial preload, radial load, or shaft shock can shorten bearing life and reduce signal 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 scaling is set for 1024 PPR and that the installed counter can accept the selected 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 cable away from inverter output, motor, brake, and contactor wiring. After commissioning, verify pulse count, speed scaling, direction, N marker repeatability, terminal-box sealing, and signal stability through the full operating speed range.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed drive and counter system:
- Match 1024 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-1024G-90G-NG |
| Encoder type | Heavy-duty optical incremental encoder |
| Series | FG 4 |
| Connection structure | K standard radial terminal box |
| Pulses per revolution | 1024 PPR |
| Pulse disk class | Preferred nickel-disk 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 | 1024 PPR scaling, N marker, 90° phase, terminal-box shielding, coupling preload |
