Hello D-Tools Members,

Last month we discussed connector tolerances as one of the main causes of the dreaded “cable falling out of the socket” syndrome. For this month, we will continue our discussion on the factors that cause, not only the annoying and sometimes costly problem of the cable disengaging from the receptacle, but one of the main reasons for cables being out of compliance – overmolding.

The overmold is the outside shielding part of the cable that you typically use to hold the cable when plugging it into the receptacle. The easiest way to make an overmold is to use injection plastic or rubber. Unfortunately, while cheap to produce, these materials are typically quite heavy, and in some circumstances, over the allowed amount listed in the HDMI Specification (Section 4.1.9.2). In fact, overmolding out of the specified range is one of the most common factors of HDMI cables being “out of Specification.” Large and heavy overmolding coupled with large gauge cabling will make a cable heavy right at the critical juncture of where it plugs into the unit.  This ‘perfect storm” will especially be evident when running long cables to such devices as projectors. Again, the decision to use a heavy material in the construction of the overmold does not add anything to performance, but really only saves dollars off the bottom line.

Another reason that out of specification overmolding is an important consideration is that it can block other HDMI ports. In many units, HDMI ports are stacked pretty close each other. With an out of specification overmold, these ports are easily blocked and cannot be used.

In some circumstances, overmolding is purposely made out of specification to incorporate “features” such as locking mechanism. Please be aware that any overmold, regardless of whether it is designed or made in error are still out of specification.  Also ,be aware that some of these designed locking mechanisms where you modify the port by adding a adapter that allows you to screw the overmold to the unit, are not only out of specification, but can potentially damage the unit should enough force be exerted on the cable to pull the internal components out of the unit.

Light weight, elegant overmold made from aluminum.

Out of compliance “screw lock” type connector

Bottom line: Not all HDMI cables are created equal. Overmolding may seem like a small detail, but the ramifications of having an out of specification overmold can make a difference in your installation and overall customer satisfaction.

Next month we will continue our discussion with the dreaded “HDMI Trademark and Logo Guidelines.” We will discuss how the guidelines impact cable construction and, hopefully, demystify and help alleviate some of the confusion around this important topic.

Also, if you need to catch up on any of the other topics on HDMI cable construction 101, please feel free to check out any of the previous discussion by clicking here.

As always, should you need any additional information on this topic or any other HDMI related issues, please feel free to drop me a line.

Michael Schaller
mschaller@kordz.com

+01.408.656.6090