MJS 1 Equivalent & Substitute Parts

Part Overview

The MJS 1 is a 1 A 250 V AC/DC fuse cartridge with glass construction in 2AG package format (5mm x 15mm axial). This through-hole mounted slow-blow fuse is designed for circuit protection applications requiring moderate current ratings and standard voltage specifications. The MJS 1 carries an Obsolete product status, making identification of suitable alternatives necessary for ongoing system maintenance and new design implementations.

Substiute Parts

MJS 1

Bel Fuse Inc.In Stock: 777MJS 1 Datasheet

Current PartRFQ

MJS 1-R

Bel Fuse Inc.In Stock: 989MJS 1-R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

The MJS 1-R qualifies as a direct substitute based on identical electrical and mechanical parameters. Substitution is valid when the following criteria are met:

• Current Rating: 1 A (exact match)
• Voltage Rating (AC): 250 V (exact match)
• Fuse Type: Cartridge, Glass (exact match)
• Package / Case: 2AG, 5mm x 15mm (Axial) (exact match)
• Response Time: Slow Blow (exact match)
• Mounting Type: Through Hole (exact match)
• Breaking Capacity @ Rated Voltage: 200 A (exact match)
• Operating Temperature Range: -55°C ~ 125°C (exact match)
• Melting I²t: 6 (exact match)

The MJS 1-R maintains full electrical and mechanical compatibility with the original MJS 1 specification.

Parameter Comparison

Engineering Selection Recommendations

The MJS 1-R is the appropriate substitute for the obsolete MJS 1. Both components are manufactured by Bel Fuse Inc. and maintain identical electrical and mechanical specifications across all critical parameters including current rating, voltage rating, fuse type, package format, and response characteristics.

The MJS 1-R offers the advantage of Active product status, ensuring continued availability and supply chain reliability. The MJS 1-R also provides ROHS3 compliance, whereas the original MJS 1 is RoHS non-compliant. Both components carry equivalent international approvals (CE, CSA, PSE) with the MJS 1-R including cULus certification.

The DC cold resistance differs between the two parts (0.281 Ohms for MJS 1 versus 0.19 Ohms for MJS 1-R), but this variation remains within acceptable tolerances for slow-blow fuse cartridges and does not affect functional compatibility in standard circuit protection applications.

Frequently Asked Questions (FAQ)

Q: Can MJS 1-R be used as a direct replacement for MJS 1?

A: Yes. The MJS 1-R is a direct substitute. All electrical parameters (current rating, voltage rating, response time, breaking capacity, melting I²t) and mechanical parameters (package format, dimensions, mounting type) are identical.

Q: What is the difference in DC cold resistance between MJS 1 and MJS 1-R?

A: The MJS 1 has a DC cold resistance of 0.281 Ohms, while the MJS 1-R has 0.19 Ohms. This difference is within normal manufacturing tolerances for slow-blow fuse cartridges and does not impact circuit protection performance.

Q: Why is MJS 1 listed as Obsolete?

A: The MJS 1 has reached end-of-life status. The MJS 1-R, which is Active, provides equivalent functionality and is the recommended alternative for new designs and replacements.

Q: Are there any compliance differences between MJS 1 and MJS 1-R?

A: The MJS 1-R is ROHS3 compliant, whereas the MJS 1 is RoHS non-compliant. Both components carry CE, CSA, and PSE certifications. The MJS 1-R additionally includes cULus certification.

Q: Is the 2AG package format standard for both parts?

A: Yes. Both MJS 1 and MJS 1-R use the 2AG package format with dimensions of 5mm x 15mm (0.217" Dia x 0.591" L) for through-hole mounting applications.

Q: What is the operating temperature range for these fuses?

A: Both the MJS 1 and MJS 1-R operate across the temperature range of -55°C to 125°C.