Acoustic guitars come in all shapes and sizes with a number of options. One of the most popular options is the addition of a pickup system that allows the guitar to be plugged into amplification.
When a pickup system is added to an acoustic guitar it becomes an "acoustic/ electric" guitar because it can be played on its own, acoustically, or connected to an amp or PA system like an electric guitar.
And as with anything mechanical, the more pieces you add to the puzzle, the more that can go wrong. If you have an acoustic/ electric guitar it's just a matter of time before you experience a break down in the signal chain, and it's important to know how to diagnose the problem.
Issues that can arise when plugging an acoustic/ electric guitar into an amp or PA system typically fall into two categories. Distorted or static sounds - or complete loss of signal.
Distorted or Static Sounds
When the sound that the guitar produces is distorted or full of static, there are a couple of culprits.
The first thing to check is the guitar cable you are using. Gently shake the cable and listen for a "crackling" sound. If you hear one then the cable may have a short somewhere down its length. Also, apply some pressure back and forth on the ends. If you hear a crackling sound then that is usually an indicator of a short in the cable connectors.
Either way, try a new cable and see if that alleviates the problem.
If not, try gently moving the end of the cable that is plugged into the guitar back and forth. If this produces a crackling noise then you may have a short in the input jack of the guitar itself.
If you have tried all of the above and not located a problem, then the next thing to check is the battery for the pre-amp of the guitar's pickup system.
Most acoustic guitar pickups have a pre-amp built in that boosts the signal out of the guitar before it goes to an amp or PA. One of the most common problems with these guitars is that the battery (often a 9 volt) loses power, or dies out altogether. Put a new battery in and try the guitar. This, quite often, will solve the problem.
Complete Loss of Signal
Diagnosing this problem is similar to the above issues, but since there is no signal at all you will want to check the other parts of the signal chain.
First check the amp. I know this sounds obvious, but make sure it's on! If so, check volume level settings. Use another guitar that you know is working and make sure the amp is functioning properly.
If the guitar is plugged into a D.I. (Direct Box), check the box for defects and proper cable routing. Also check the XLR cable that goes from the D.I. box, to the mixing board or snake.
Once those possibilities are eliminated, then proceed to diagnose issues as with a distorted or static sound.
The above troubleshooting tips may sound like a lot of steps to go through to discover the problem, but once you have a grip on the concept of what can go wrong, you will find that tracing down the problem can be done fairly quickly.
It's really just a matter of knowing the signal path of the guitar, and eliminating everything that "is" working, until you find the thing that "isn't" working.
And remember, the number one culprit of signal loss, or distorted signal in an acoustic/ electric guitar is a faulty battery - and you can solve that problem by changing the battery often!