EMC Emission Issues - Communication between PC and Monitor



We are currently testing our device on EMC emissions, and unfortunately we are over the limit. We have found the source of our problem which is the communication between the PC and the monitor. The cabled are acting as antennas.

We are currently using an adapter from DVI to optical fibre. This reduces the emission a lot, but just not enough to pass the test. The troublesome frequency is at 742.5 MHz.

Have some of you encountered a similar problem regarding EMC and have you found a solution for the communication between pc and monitor?


I would look very carefully at the PC board layout of the DVI interface (and the rest of the board also) and the way the shield on the cable is connected to the enclosure shield and PCB ground. DVI is used other places without fiber optic interface so it is possible to pass.
For help on this look at Bruce Archambeault's book "PCB Design for Real-World EMI Control" and Henry Ott's book "Electromagnetic Compatibility Engineering".
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