DC Screw Lock Cable with Threaded Retaining Collar Barrel Plug

Overview

A plain barrel plug is held in by nothing more than the spring of the jack contact, which is enough on a bench and not enough on anything that moves. This DC screw lock cable puts a threaded retaining collar on the plug, so it screws onto a matching thread on the jack and turns a friction fit into a clamped one. The plug has to be unscrewed before it can come out.

Key Specifications

Barrel size and thread reference

Barrel plugs are described by three numbers and people usually quote one. The outer diameter of the barrel, the diameter of the center pin bore, and the length of the barrel all have to match the jack. These are the sizes we already tool; anything else is built to your sample.

Three dimensions to measure before you order

1. Outer diameter of the barrel, measured across the metal sleeve with calipers, not by eye.
2. Center pin bore, measured on the jack pin. A plug with an oversized bore on a small pin makes contact over a reduced area, which shows up as voltage drop and heat rather than an open circuit.
3. Barrel length. A plug that is too short bottoms out; a plug that is too long never seats, and the collar then appears to be tight when the contact is not made.
4. The collar thread, if the jack is already threaded. Measure the outside diameter of the jack thread and the pitch, or send the jack.

Forcing a plug with an oversized center pin into a jack made for a smaller one spreads the contact spring permanently, and the jack is then loose for every plug that comes after it.

Polarity is not guessable

Nothing about the connector forces a polarity. Center positive, where the tip carries the positive rail and the barrel is ground, is the common convention, but center negative exists and audio-adjacent and pedal equipment is a regular offender. Reversed polarity on a device with no input protection destroys it the first time it is plugged in. Read the symbol molded or printed next to the jack on the equipment, not the label on the old adapter, and confirm it before you order.

Why the friction plug walks out

• Contact spring force is the only retention, and it falls with every mate and unmate cycle.
• Vibration does the rest: on a machine frame or a cart, the plug migrates out over weeks.
• The symptom is an intermittent reboot rather than a clean shutdown, which is expensive to diagnose.
• Once it has backed out part way, arcing pits the contact and the jack is damaged as well as the plug.

Typical applications for this DC screw lock cable

• Industrial panel PCs and HMIs mounted on a vibrating machine frame
• LED lighting fixtures and signage drivers in ceilings and soffits — see also the LED power injection cable
• Kiosks, ticketing machines and vending units that are serviced in the field
• CCTV cameras on poles and on pan-tilt heads
• Medical carts and test carts that are wheeled around all day, where the medical panel feedthrough set handles the panel side
• Retrofits onto an existing threaded jack, using the threaded locking DC pigtail

What we need to quote

• Barrel dimensions: outer diameter, inner pin diameter and barrel length, measured or read off the existing jack.
• Collar thread on the jack, if it is already threaded, or the jack part number.
• Polarity as fitted on the equipment, center positive or center negative.
• Voltage and the continuous current the load draws, so the conductor size and jacket are chosen correctly.
• The other end: stripped and tinned, ferrules, a second barrel plug, or a different connector entirely.

Ordering and lead time

DC barrel plug dimensions are conventions rather than a standard, which is exactly why we build to a measurement instead of to a catalog number. Send the jack, a photograph with a scale, or the equipment part number and we come back with a build we can hold to.

DC Screw Lock prototype lots start from 1 to 50 pcs and ship in 3 working days; production requires 500 pcs and runs 14 working days after sample approval. Your part number and labeling go on OEM and ODM DC shipments, and material certificates with first-article reports are available. We hold 100 sets of mold tooling in house, so a standard body needs no tooling time and a new one adds about 10 working days.

Workmanship and testing

For DC Screw Lock builds the line runs to IPC/WHMA-A-620 Class 3 under ISO 9001, terminating 32 to 12 AWG. continuity and pinout are tested on each DC unit before it is packed, and seal checking is quoted whenever an ingress rating is on the drawing.

Material declarations against RoHS and REACH are issued per project, alongside the dimensional and electrical reports agreed at quotation; see certifications, compliance and material declarations. Where your drawing names a UL style or another approval, the build follows your drawing and ships with the supporting document rather than a claim of our own. Where this build needs an overmold, the tool is designed, cut and maintained in our own shop under the overmold tooling we build in-house, and it is never used for another customer’s program. More background: build-to-print cable assemblies.

Related power assemblies

• Threaded locking DC pigtail, 5.5 x 2.1 mm
• IP67 waterproof DC extension cable
• DC barrel pigtail cable to bare wire or ring terminals
• USB-C PD trigger power cable to a 5.5 x 2.1 mm barrel

Full ranges: DC plug power cable and screw-lock molded cable.

Frequently Asked Questions