Thursday, May 31, 2012

USB Problems and How To Fix Them

Unique USB Fixes to Common Problems


USB Product Video

USB products are everywhere. From cell phones, smart phones, digital cameras, tablet computers, camcorders, and just about every other gadget uses USB connectors on it. So you are very likely to need a USB cable, adapter, or other connectivity item as a common fact of modern life.

But USB isn't perfect. Common USB problems include:

  • Friction fit connectors popping out of their jacks if pulled or vibrated
  • Difficulty mounting a USB female on a panel or faceplate
  • Sensitivity of USB to dirt, dust, moisture, and other ingress
  • Plugging in a USB connector in tight spaces

Fortunately, solutions to these problems are not hard to get, as you can see from this video.  USB connectivity equipment is commercially available and often costs very little compared with the headaches of dealing with the problems above.

Latching USB Cables

Latching USB Drawing

USB connectors use what's called "friction fit" to hold the plug in the jack when connected, which you may notice as you plug or unplug a USB cable.  This is as opposed to things like screw or lock connectors, which maintain a firmer connection. Friction fit isn't a problem, and in fact makes it very quick and easy to plug and unplug a cable without having to unscrew it or unlock it. However, in some applications, the friction fit design is a problem.  Consider military vehicles that may experience frequent and jerky vibrations as they are driving across a battlefield. If occupants are using USB devices, the vibration is often enough to disconnect them, and often the connection is critical.

L-com's latching USB cables use a unique design modification to the type A male connector. It adds tiny spring latches on the sides that can be depressed by squeezing the sides of the molding behind the connector. Once mated, the latches spring out and hold the connector firmly in place. Also, and following with the military applications, L-com offers LSZH rated latching cables for applications where cable burning is a concern and halogen gasses cannot be tolerated. If you have a USB application and you've noticed that the friction fit is a problem, consider getting one of these.

Bulkhead USB Adapters

ECF Style Diagram

The opposite of the Type A male issue above is how to mount female jacks so you can mate to them easily. Again, one of the advantages of USB is that it is quick and easy to plug and unplug your portable devices. But sometimes your computer or other USB host device is in an inconvenient spot, maybe behind an equipment rack, deep under your desk, on a shelf, or sometimes even in another room. In these cases, the ability to mount a female USB port somewhere that you can easily reach is a huge help.

Bulkhead USB products come in various types, but the most common two are the "ECF" flange mount styles, and the side-flange mount styles.  The "ECF" styles use a sturdy, firm flange above and below the jack that can be screwed to the outside of the panel. The side-flange mount styles have smaller flanges to the sides of the jack, which can be screwed either outside or inside the panel.  Either type comes with advantages, but in general if you need a sturdy mount, use the ECF style, if you need to mount in a small space with a small footprint, use the side-flange style.

Quick Note: There are other styles for mounting available, such as this Keystone style panel-mount USB coupler and these interesting round jacks and cables. But these are more apt to be used in waterproof and dust proof applications, so we'll talk more about them next.

Waterproof USB Options

Waterproof USB Cable Connectors

Water and electricity don't mix well. Also, dust and dirt in a connector can seriously impact the connection. So any electronic cable, even a low-voltage signal cable, must remain ingress-free.  In most cases, this isn't a problem. But sometimes you need to provide USB connectivity in an environment that may involve splashes or sprinkles of water, or dirt and dust. In these cases, waterproof cables and connectors with Ingress Protection (IP) ratings could be your answer.

In order to work properly, you usually need matching jacks with cable plugs, along with waterproof covers to protect the connectors when not mated. There is a good variety of panel-mount USB jacks available, with flying leads, finished cables, or field-install solder cups on the inside of the panel (the side presumably protected from ingress). These usually use a screw barrel body to allow the male cable connector to screw a waterproofing hood to it.

Right Angle USB Products

USB 2.0 Type A Low Profile Right Angle Adapters

If you need to get a USB cable into a tight space, you've no doubt noticed the immense difficulty with bending the back of the connector at a tight angle. USB cables have a minimum bend radius of 10x the outer diameter of the cable, and exceeding that can add stress to the connector on the cable and the jack that it is connected to.  Fortunately, widely available and moderately priced right angle adapters and cables can easily solve the problem.  Make certain you understand what kind of an angle you need, however. It is sometimes difficult to tell the difference between the "top" and "bottom" of a USB Type A connector, but it will only plug in one way. If you get the wrong angle, the adapter or cable won't mate.  Fortunately, this helpful guide shows close-ups of the connectors to explain which angle you need.  Also, you can always look into Flexible USB options, like flexible adapters and flexible cables.

Quick Note: There's a lot more out there for USB applications, such as customizable USB products, passive USB extenders, active USB converters, wireless USB equipment, and a range of USB 3.0 items. Check out a comprehensive USB tutorial here.

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