Home Stereo Troubleshooting - One Channel Out

One common problem with home stereo systems in the loss of one or more channels of sound.  Sometimes this occurs constantly, and sometimes it happens only intermittently.  The best way to isolate such problems to a single component in the system is to swap cables to see if the problem remains in the same channel or switches to a different channel.

For instance, if the your right channel speaker is out, connect its speaker wire instead to your amplifier's or receiver's left channel speaker terminals.

If the right speaker is still out, it is obviously bad.

But, what if the right speaker starts working?  Obviously, then, the right speaker is not bad.

The next step is to connect the left speaker wire to the amplifier's or receiver's right channel speaker terminals.

Most likely, the left channel speaker, which was working before, will not work.  This proves that the right channel speaker terminals on the amplifier or receiver are not working.

At this point, you have pretty much established that the problem is the right channel speaker output from the receiver or amplifier, and not the speaker or wires.

Looking at it another way, the problem always "follows" the bad component:  If the right channel speaker output of your amplifier or receiver never works on any speaker, then it is the problem; if your right speaker never works wherever you connect it, then it is the problem.

The same process can be used to isolate problems with other components in the system.  For example, your system might have a tuner, a preamplifier, and a power amplifier.  The signal comes from the tuner, passes through the preamp, passes through the power amplifier, and goes to the speakers. A problem in any of the components along this chain could cause a speaker to go out.  If, for instance, you notice that your right speaker is out, you might not know where to start.

Step 1.  Swap the speaker wires, as described above to eliminate them as the source of the problem.

Reconnect the speaker wires as they originally were before proceeding to the next step.

Next, you want to see if the amplifier is bad, or if the right channel is out on some other component back up the chain.  So:

Step 2.  Swap the left and right cables between the preamp and the power amp, i.e. connect the left preamp output to the right power amp input, and the right preamp output to the left power amp input.

If the right speaker starts working, and the left speaker quits, you have proven that there is no output from the preamp's right channel.

You also know that the power amplifier is OK, because its right terminals are still connected to the right speaker, which is now working.

Reconnect the preamp-to-power amp cables as they originally were before proceeding to the next step.

Still, the tuner could be bad [see Shortcut, below], so you:

Step 3.  Swap the cables between the tuner and the preamp, i.e. connect the left tuner output to the right preamp input, and the right tuner output to the left preamp input.

If the right speaker starts working, and the left speaker quits, then you know the tuner is bad.  You also know that the preamp is OK, because its right output is still connected to the right channel of the power amp and the right speaker, which are both now working.

Reconnect the tuner-to-preamp cables as they originally were before proceeding further.

Tips:

Note that this same process can be used on any combination of components in the system.  You just apply the same principles to whatever components you have.

Problems other than one channel out can be traced this same way.  If you have noise in one channel, or if one channel works intermittently, just substitute the words for the particular problem you are having in place of "out" in the procedure above.

You can also do this for multi-channel and surround-sound systems, except that there are more channels to swap and more chances for confusion.  I used a stereo system with "right" and "left" channels in the above example for simplicity's sake.  For multi-channel systems, just chose one good channel and one bad channel and swap those two consistently throughout the process.  If you have more than one channel out, just repeat the process for each bad channel.

Besides failures of the components of a system, it's possible for the cables, themselves, to fail.  To eliminate cables as a source of trouble, you can swap the left and right channels of a cable at both ends at the same time, i.e. take out the white connectors at both ends of a cable and plug them in where the red connectors were.  Likewise, take both of the red connectors and connect them where the white ones were.  Doing this swaps only the cables, so, if the problem switches from one channel to another, you know the cable is bad.
If it's less confusing, just connect one complete cable of the pair at a time.  If the white cable gives you sound all the time, but the red never does, then the red half of the cable is bad.

"RCA" type audio cables have color-coded ends that identify the left and right channels.  There are a few different color codes, but these are most common:

Red = Right channel,
White = Left channel, or

Red = Right channel,
Gray = Left channel, or

Red = Right channel,
Black = Left channel.

"RCA" type connectors on the backs of components will sometimes also be color-coded, usually with:

Red = Right channel,
White = Left channel.

I recommend always connecting the cables using the red plug for the right channel.  Although it makes no difference in performance, using the color code helps keep track of which channel is which and which cables you moved during troubleshooting.  At the end of each experiment, reconnect the cables according to the color code so you don't "pollute" the results of later experiments.

Pitfalls:

It's easy to get confused when swapping wires and cables.  To avoid problems:

Always swap the wires back the way they originally were and confirm that the original problem returns before proceeding to the next step.  This prevents multiple changes from confusing your experiment.

Intermittent problems are those that occur only sometimes.  They can cause confusion by starting or stopping during your troubleshooting, leading to a wrong conclusion.  Be sure that the problem you are troubleshooting is happening before you start swapping cables.  If not, you may have to wait for something to stop working before you try troubleshooting.  Likewise, when you think you have found the cause of a problem, repeat the experiment several times.  If swapping cables consistently "fixes" the bad channel and "breaks" the good one, then you be assured that your found the problem.

Simultaneous failures:

In the very first example above (in paragraph 2), the problem was no sound from the right speaker.  Although unlikely, it's possible that both the right speaker and the right channel of the power amp could be bad.  Keep this in mind if you seem to be getting conflicting results form your tests.

Shortcut:  If one channel is out on only one source, e.g. tuner, CD, turntable, TV, etc., try the other sources to see if they also have the problem.  If the other sources work, and only one source has the problem, that source or its cables are likely at fault.  [It is uncommon for one input on a preamp, integrated amp, or receiver to go bad, but it can happen if that input is processed separately from all others.  Phono inputs sometimes go bad by themselves.]  If all sources have the problem, then continue with Step 3.