Multi-turn wirewound potentiometers are critical in precision instrumentation, industrial signal conditioning, and audio calibration for providing stable, fine control. The Bourns 3590S series is an industry-standard family of 10-turn precision potentiometers, trusted for applications requiring high adjustment accuracy and long-term reliability.

While the 3590S-2-103L, 3590S-1-103L, and 3590S-2-502L share a nearly identical form factor, they differ in critical parameters such as shaft specifications and resistance values. Relying solely on visual appearance or series designation can lead to mechanical mismatches or improper adjustment ranges.

Using the 3590S-2-103L as the reference model, this guide compares the variants from a specification and application perspective to ensure correct selection and substitution.

Parameter Comparison

Application Analysis

• 3590S-2-103L

Best For: General industrial control panels, power supply biasing, and standard calibration equipment.

Insight: This is the “go-to” reference model within the 3590S series. It balances electrical performance with standard mechanical compatibility. Its resistance covers most voltage divider needs, and the shaft fits standard 1/4″ knobs. Without specific constraints, this is the most compatible and lowest-risk choice.

• 3590S-1-103L

Best For: Equipment requiring specific fit tolerances, legacy systems, or knobs designed for slightly undersized shafts (0.248″).

Insight: Electrically identical to the reference model, the difference lies purely in the mechanical interface. The shaft is slightly smaller (0.248″ vs. 0.2497″), optimized for specific knob tolerances. Critical: Always verify mechanical fit, especially for collet-style knobs, to ensure proper clamping.

• 3590S-2-502L

Best For: Low-impedance voltage dividers, sensor calibration, and signal generation.

Insight: The key differentiator is the 5 kΩ resistance. It is intended for designs requiring lower output impedance or higher current drive. It is not a drop-in replacement for the 10 kΩ models without verifying circuit power dissipation and loading effects.

Design Considerations

• Knob-to-Shaft Compatibility

The shaft type code (-1 vs. -2) is a frequent source of assembly errors.

Set Screw Knobs: Both shaft types are generally compatible.

Collet/Interference Fit: Precision is critical. The reference shaft (0.2497″) fits standard hardware; the -1 shaft (0.248″) is looser. Mismatches can cause eccentric rotation, poor clamping, or slippage over time.

• Wirewound Characteristics

Being wirewound, these potentiometers exhibit finite resolution steps and may generate minor wiper noise during rapid adjustment. While acceptable for industrial use, ultra-sensitive audio or analog front-ends may require evaluation or a conductive plastic alternative if infinite resolution is needed.

• Power Derating & Environment

Rated power applies to controlled conditions. In high-temperature or enclosed environments, apply proper power derating to reduce thermal stress. This improves reliability and minimizes resistance drift caused by temperature coefficients.

Replacement & Substitution Recommendations

• 3590S-2-103L ↔ 3590S-1-103L

Electrical: 100% Compatible.

Strategy: You can substitute one for the other if the knob fastening mechanism allows it (e.g., set screws). If using precision dials or collets, measure the bore diameter to prevent a loose fit (using -1) or an impossible fit (using -2).

• 3590S-2-103L ↔ 3590S-2-502L

Mechanical: 100% Compatible.

Strategy: Do not swap without calculation. Replacing 5 kΩ with 10 kΩ changes the load current and circuit bias; replacing 10 kΩ with 5 kΩ at the same operating voltage doubles the current and power dissipation, risking component failure.

Key Takeaways

• 3590S-2-103L: The Standard Choice (10 kΩ, 1/4″ shaft).
• 3590S-1-103L: The “Special Fit” Choice (10 kΩ, 0.248″ shaft).
• 3590S-2-502L: The Low Resistance Choice (5 kΩ).

WIN SOURCE offers stable inventory and technical support for the Bourns 3590S series. From selection to legacy replacement, we ensure accurate alignment of electrical and mechanical specifications. Visit WIN SOURCE for real-time stock and pricing.