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Most people don't take especially good care of analog A/V cables, and they are often subjected to getting stepped on repeatedly, chewed by pets, etc.

If an analog A/V cable (component, composite, etc.) is damaged and the center conductor shorts with the outer shield, would this result in any electrical damage to the connected devices?

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  • \$\begingroup\$ This is impossible to answer. Every design is different and the design considerations are unknown. \$\endgroup\$ – Matt Young Apr 9 '13 at 20:27
  • \$\begingroup\$ I'm asking in general for common consumer devices (tv's, projectors, receivers, etc.) Do these types of standard a/v cables carry enough current to do damage in a short circuit situation. Or would a damaged cable just cease to work, causing no ill effects? \$\endgroup\$ – BobRalph Apr 9 '13 at 20:58
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While it varies, for standard audio and video cables, a short shouldn't cause too much issue if any. Line Level audio has very little current, and goes through dc blocking capacitors and series resistors, into amplifiers, in most equipment. Yet you can still use a Mono 3.5mm cable on a Stereo Jack. The Right channel, normally on the middle Ring, would be shorted out to Ground, and has no affect on most devices. Same goes for 4 conductor TRRS jacks and 3 Conductor TRS cables.

Shorting a line level output to it's own ground isn't a problem. Same for composite video. I do not know if the same can be said for component or rgb connections. It's when either ground or the a/v signal is shorted to a power source that the issue occurs.

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  • \$\begingroup\$ Yes that's what I meant, a line level output shorting to it's own ground. I have seen a coaxial antenna cable have 1 strand of the braided shield sticking out and touching the center pin causing the signal to drop out. I just wondered what the consequences of a similar short in a/v RCA jacks would cause. As far as I know, component would be the same as composite since they share the same physical jacks on many TVs these days. \$\endgroup\$ – BobRalph Apr 9 '13 at 22:46
  • \$\begingroup\$ @BobRalph just because physical jacks match doesn't mean that the internal topology of the signal/specifications/device will match and act the same though. \$\endgroup\$ – Passerby Apr 9 '13 at 22:48
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The amounts of power that need to be conveyed through analog A/V cables other than speaker wires is generally pretty small, and most devices which output analog audio or video are incapable of outputting so much power as to damage themselves in the event of an output short circuit. Some devices may output power through a cable along with an audio or video signal, however, and a short between the power wire and a signal wire could cause damage.

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Suppose you have a small-signal audio output implemented as an op-amp stage. If the op-amp has no short-circuit or thermal protection, and you ask it to drive a short circuit, it will probably be permanently damaged. This is true even if the output is AC coupled via a capacitor because the capacitor is transparent to the AC signal, which could have a large signal swing, resulting in a large AC current. An AC short is just as bad as a DC short.

Analog inputs can usually be shorted. This is because they frequently are. Output circuits usually have a low impedance, often very low: close to zero. Furthermore, outputs sometimes go to 0V, like when there is no signal. A low impedance at 0V is a virtual ground: the input is basically grounded when driven at 0V by a low-impedance output. It's even a good idea for unused inputs to be grounded, to reduce opportunities for noise to enter into the device. Sometimes switched input jacks are used to automatically ground inputs when the plug is removed.

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