Madrigal Imaging N38 manual Ground Isolation Adaptor

Noise in A/V systems

Ground Isolation Adaptor

In some cases, connecting your audio and video systems together in this fashion can result in noise, typically a 60 Hz or 120 Hz hum. The most common cause for this noise is a “ground loop” caused by the presence of two ground references in the system: one from the power company and another from the cable-television company. The simplest way of solving this problem is to break the cable company’s ground by using an isolation transformer on the incoming cable line, before it reaches your television or VCR. If you cannot find a 75Ω -75Ωbalans (isolation) transformer, you can easily construct one from the adaptors which probably came with your VCR and television, as shown below.

Ground Isolation Adaptor

75Ω 300Ω 300Ω 75Ω

place in-line with your cable feed, prior to the system connection

The assembly shown above may cause some loss of video signal strength and/or bandwidth, and should be used as a temporary fix. It is useful in determining the cause of some video-related noise problems, however. If it seems to correct a problem, consult with your dealer regarding a long-term solution which does not degrade video performance.

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