Vintage ALPS Full-Sized Tapped Potentiometer

Stereo 250K Linear | Dual Centre Loudness Taps | PCB PIN Layout | Japan NOS Pair

👨‍🛠️ Bench Verification & Technical Condition

Up for sale is a pair of New Old Stock (NOS) vintage 1970s ALPS Japanese-Made full-sized dual-ganged stereo potentiometers. This high-grade audio component features a robust 24mm can architecture engineered with a unique dual-sided 8-terminal configuration: 6 downward vertical pins handle the main resistor tracking loops while 2 opposite-facing terminals house the independent physical loudness taps as traditional hollow solder tags. Built with a stamped metal faceplate bracket hosting a flat anti-rotation panel alignment locating pin. Sourced as original repair stock and safely preserved in dry workshop drawers for decades, these components remain entirely unused, unmounted, and have never seen a single drop of solder.

Verified Linear Track Curve: Factory stamped with the classic ALPS 5NC-250KΩBX2 series identifier sequence. Confirmed via multimeter measurement to provide a highly uniform linear distribution curve across both ganged tracks, ensuring perfect stereo tracking balance.
Symmetrical Centre Loudness Taps: Outfitted with independent centre tap lines on the reverse side of both decks terminating in clean solder tabs. Direct bench diagnostics confirm that the physical loudness taps and mechanical midpoints sit perfectly synchronized right at the dead-centre 50% mechanical half-turn mark.
Flat Structural Safety Pin: Stamped metal mounting faceplate plate features a solid flat anti-rotation tab adjacent to the threaded collar block. This key slots into panel sub-frames to completely eliminate tracking chassis rotational twist under continuous operational knob torque.
Fluted Aluminium Shafts: Standard 6mm diameter solid aluminium split-spline shafts measuring a generous 28mm visible extension length (35mm overall length including the 7mm threaded collar block face). Perfect for standard push-on vintage knobs.

🔹 INDEPENDENT BENCH DIAGNOSTICS & RESISTANCE RATIOS:

- Mechanical Operation: Smooth Continuous Non-Stepped Rotation with Flat Panel Alignment Pin
- Termination Architecture: 8 Active Connection Nodes (6 Vertical PCB Pins + 2 Opposite Solder Tags)

🏷️ POTENTIOMETER #1 READINGS:
- Front Section (Pins 1 to 3): 245.400 kΩ Max | 50% Mechanical Midpoint & Loudness Tap (Pins 1-2 / 1-4): 122.000 kΩ
- Rear Section (Pins 1 to 3): 244.600 kΩ Max | 50% Mechanical Midpoint (Pins 1-2): 125.000 kΩ | Centre Loudness Tap (Pins 1-4): 124.700 kΩ

🏷️ POTENTIOMETER #2 READINGS:
- Front Section (Pins 1 to 3): 272.500 kΩ Max | 50% Mechanical Midpoint (Pins 1-2): 147.000 kΩ | Centre Loudness Tap (Pins 1-4): 146.600 kΩ
- Rear Section (Pins 1 to 3): 265.000 kΩ Max | 50% Mechanical Midpoint (Pins 1-2): 134.700 kΩ | Centre Loudness Tap (Pins 1-4): 134.800 kΩ

- Physical Frame Footprint: 24mm Full-Size Can Diameter Casing Body (Total frame span length 56mm tip-to-base)

📊 Factory Component Specifications

Brand / Manufacturer	ALPS Electric Co., Ltd. (Made in Japan)
Full Manufacturer Part Number	5NC-250KΩBX2
Taper Architecture Code	"B" - True Linear Taper Profile Curve with Centre Taps (Japanese JIS standard)
Nominal Resistance Base	250 kΩ Nominal Base Class (Batch verified tracking between 244kΩ and 272kΩ Max)
Architecture Layout	Dual-Ganged / Stereo Coaxial Configuration with Independent Dual Centre Loudness Taps
Terminal Style Configurations	8-Pin Hybrid: 6 Downward Vertical PCB Pins + 2 Opposite Side Hollow Solder Tags
Casing Footprint Diameter	24mm Full-Size Can Main Housing Footprint
Mechanical Structural Security	Stamped Tin Bracket Faceplate with Flat Metal Anti-Rotation Locating Tab
Shaft Interface Dimensions	6mm Diameter \| Fluted Solid Aluminium Split-Spline Layout
Shaft Extension Measurements	28mm Visible Shaft Alone (35mm Overall Length Including Threaded Collar Bushing)
Total Component Length	56mm End-to-End Footprint Profile (From casing can backing plate to spline tip)
Era & Origin / Condition	Vintage 1970s Production \| Made in Japan \| New Old Stock (NOS)

📻 Vintage Solid-State Stereo Restoration

This robust, dual centre-tapped 250K linear control is an essential original resource for classic audio repairs:

Premium Integrated Amplifiers & Tuning Stages: Direct drop-in match for loudness-compensated volume matrices or advanced active tone/feedback filtering networks inside classic 1970s **Pioneer, Sony, Sansui, Sanyo, or Marantz** solid-state lines.
Flawless Track Continuity: Pristine internal carbon elements completely shield your signal path from tracking mismatches, sudden level surges, and scratchy tarnish noise common in aging original assemblies.

📮 Combined Shipping Policy

Clearing out multiple vintage assets from your workspace project bins? I will gladly manually combine shipping costs across all active listings to save you money on postage. Please add your items to your cart and request a final total before making your payment so I can issue an adjusted invoice based on the true package size and weight.

⚠️ Vintage Electronics Disclaimer

This item is a premium New Old Stock (NOS) component from an accumulation of classic workshop stock. While it has been cleanly bench-tested to confirm precise track resistance, switch continuity, and smooth tracking, vintage electrical hardware components are sold as-is without modern commercial warranties. Please review all dimensions and chassis shaft profiles closely before purchasing. Added this!!