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RCA jacks are constructed such that the inner pin of the plug cannot contact the outer ground ring at the same time that it is contacting the jack's inner pin contact. Disconnecting the plug could short the signal line of the cable to ground, but only after disconnecting from the DSP - the device that would see the short would actually be the amp on the other end of the cable.

Also - I'm not seeing it listed as a feature on the data sheet, but most op-amps are protected against short circuits on their output; a brief short wouldn't cause it to blow like that. If that particular op-amp is sensitive; then there should be current-limiting resistors in series with it's output to prevent just such an occurrence.

I suspect that you just got unlucky and the op-amp chip just happened to blow co-incidentally.
 

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I'm not an EE, but I do design stuff as a hobby (professionally I'm a software guy).

I mostly agree with yobbo7 - if hot-plugging a RCA causes a device to fail (especially in the manner that this one did, where an IC lets out the "magic blue smoke") then it was indeed designed by morons.

However - the speaker damage thing is a real possibility; as you can end up sending a nasty high-power transient into a tweeter that just can't handle it. Functionally, it's the same thing as driving the amp into clipping, hard.

Based on the apparent damage; it looks like that op-amp chip developed a short across the power rails. A transient across the output pin usually won't do that - you could very well destroy the ability of the op-amp to produce an undistorted output signal - but making a continuous short between the positive and negative rails is unlikely.

I think you just got unlucky.

BTW - some connections are specifically designed to accommodate hot-plugging: MIDI ports, Ethernet ports; most RS232, RS422, and RS485 ports, USB ports, many (but not all!) VGA ports, headphone jacks, and some PCI slots (typically found in server-grade machines where you want to avoid having to restart the system to replace a failed card) all come to mind. You probably wouldn't find it in serious use today, but the LocalTalk networking system used by classic Macs was also hot-pluggable; but the ADB keyboard & mouse ports weren't - you could fry your ADB chip on the motherboard by plugging in a keyboard or mouse while the Mac was on (fortunately ADB hasn't been a thing since the late '90s - it's all USB or Bluetooth instead).
 

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Whatever actually did transpire is definitely highly unlikely: either unplugging a line-level signal fed a big enough energy spike into the output pins of that opamp to cause a short across the power rails, or it blew at just the moment the plugs were being messed with.

:unsure:
 

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You should never fuse the ground wires - only the hot (+12v) ones. It's important to maintain ground continuity no matter what; and if there's a short that's drawing inordinate amounts of current, one of the fuses in the hot side of the circuit will blow to prevent a fire.

It's possible that the amp has a bad ground - enough continuity to function, but bad enough that the chassis ground of the amp rises in voltage relative to the frame of the vehicle. High powered amps have an internal DC-to-DC converting power supply that generates more than enough voltage for you to feel it if you touch one of the amp's hot power rails. The fact that you are getting zapped touching the case of the amp makes me highly suspicious...

Just to clarify: when you get zapped, it's not a momentary thing, if you touch the amp again immediately afterwords you get zapped again, right? So - it's not a static discharge that's zapping you (like if you walk across a carpet and touch a doorknob, you get zapped once, but grabbing the doorknob again is zap-free)?
 

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Running parallel conductors like that is fine.

If it's just a single shock, then it could well be just static discharge - I get zapped by car frames often. Just moving around in the seat can generate quite a lot of voltage (this is why one should always wear an ESD wrist strap wired up to a good solid ground, and use a grounded ESD mat when handling unboxed electronics - i.e, bare circuit boards).
 
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