As I said, plugging into a live amp with everything cranked can cause problems for the amp, but there is
[u]no way[/u] that will damage the guitar unless there is a serious wiring problem with amp, or the AC line it's plugged into.
Guitars, and their amplifier inputs, are high-impedance circuits. There is no current flow, unless the guitar is producing a signal, or the input 'leaks'. In any case, we're dealing with
millivolts and
microamps.
If there are problems with the AC socket, the ground (shield) side of the guitar cord can be live, which can make the guitar player dead! :eek: This situation could also damage the guitar wiring, but the power-up routine you described would not help in this case.
Shorts in wiring occur when two wires are allowed to connect in ways they were not intended to. Open circuits are what happens when an intended connection is broken. Both faults occcur due to the mechanical shock and vibration that anything is subjected to when it is handled and moved around. Sloppy wiring and poor solder joints are particularly vulnerable. Long-term use will eventually cause problems with moving parts like the control pots, switches, and the jack.
The procedure you described is a good one to follow, (I do it that way myself), because it ensures that the amp is ready to run before you actually play into it, and it reduces the noise caused by transient voltages that occur when you plug in. By the way, you should always plug the cord into the guitar first, and then the amp. If you plug the cord into the amp first, the tip of the plug is connected to the input, and the amp gets fed all those crackling voltage transients as you plug into the guitar. If you plug into the guitar first, the amp input does not 'see' any signal until the plug is fully inserted into the jack.
Lordathestrings
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