FG4K-4096G-90G-NG should be replaced as a glass-disk FG 4 incremental encoder, where EncoderWorks can configure a custom compatible replacement solution only if the 4096 PPR scaling, A/B 90° phase relationship, inverted signal pairs, N marker pulse, K radial terminal-box wiring, shielded twisted-pair transmission, and coupling preload remain unchanged. The main failure boundary is a feedback system that still produces pulses but loses reference repeatability, direction stability, or EMC margin after the encoder and terminal-box layout are changed. 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 4096 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 rather than a redundant KK dual-terminal-box structure. Replacement work should focus on controller scaling, 100 kHz standard frequency margin, 150 kHz special-order boundary if applicable, A/B phase accuracy, N marker alignment, cable-gland sealing, shield bonding, and shaft coupling alignment.
System Limits
The first system limit is 4096 PPR counter scaling. Compared with 8192 PPR, this model gives more frequency margin at the same shaft speed, but the controller must still be configured for the correct pulse count and counting mode. If the drive remains set for another resolution, speed and position values can be wrong even when the A/B signals are electrically clean.
The second limit is A/B/N signal integrity. The controller must receive A with /A, B with /B, and N with /N as paired signals. If the inverted signals are not routed through twisted pairs, common-mode interference from inverters, brakes, contactors, or motor cables can become false edges, direction jitter, or marker-pulse drift.
The third limit is mechanical installation. Coupling misalignment, axial preload, radial load, vibration, or shaft runout can reduce bearing life and create rotational modulation in the output signal. A glass-disk encoder should be mounted without shock and with controlled coupling alignment.
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 the controller scaling for 4096 PPR and verify whether the application is designed around the 100 kHz standard frequency range or the 150 kHz special-order range.
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 and motor wiring. After commissioning, verify pulse count, direction, N marker repeatability, speed scaling, terminal-box sealing, and signal stability at maximum operating speed.
Custom Compatible Solution
EncoderWorks can configure the replacement around the installed drive and counter system:
- Match 4096 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-4096G-90G-NG |
| Encoder type | Heavy-duty optical incremental encoder |
| Series | FG 4 |
| Connection structure | K standard radial terminal box |
| Pulses per revolution | 4096 PPR |
| Pulse disk class | Preferred glass 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 | 4096 PPR scaling, A/B phase, N marker, terminal-box shielding, coupling preload |
