How to Repair a Car Amplifier?




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When you need to repair your car amplifier, you must know how an amplifier works.

But, how can you repair a car amplifier that just stopped working? Let’s find out. 

If you want your amp to sound great, it needs to be often cleaned inside. The dirt and dust can interfere with electronics which causes them not to work correctly or cause a protection mode when they shouldn’t. Also, if the amplifier goes to the protection mode, the ground is often wrong, and the amplifier is overheating. In this case, you have to check the wiring and make sure the connections are stable. In case of more serious damages, you should replace the car amplifier with the new one.

Tip: When cleaning the amplifier or any electronic equipment from the dust, make sure to use a proper cleaner. I use DeoxIT and have to say it works excellent.

The worst issue can happen when you have an accident, and the amplifier is physically damaged. In this case, you can take the car to the places like an auto body repair shop in Bellevue in WA that will take care of your damaged car and replace the amplifier.

This article will help give you a good understanding of amplifiers and show you some steps on how to repair one!

How Can You Tell There’s Something Wrong with Your Car Amplifier?

When you are wondering if your car amp works correctly, here are a couple of signs you should look out for:

  • No sound or low volume
  • Distortion in the sound
  • Humming or buzzing noise
  • The amplifier turns on and off by itself.

You can do a simple check of several things to see if your car amplifier is okay.

First, make sure the amp fuse isn’t blown. If this has been replaced recently, but you still don’t have power to the amp, it may need a replacement. If there is no main fuse (although it always should be installed), check to ensure the power wire (the thick red wire for a positive and black for a negative) is connected properly.

If you have determined that your amplifier isn’t getting power, test all wires using a multimeter.

If this still doesn’t fix it and your amplifier has been recently installed, there is likely a problem with the installation, and you should investigate further or take it to a professional.

If you are experiencing problems with your car amplifier, there are some basic steps that you can take to try and repair it. Keep reading to find out why your amp isn’t working and how to fix these common issues.

Why Is Your Car Amplifier Not Working?

Now that you know a few parts of a car amplifier, it is crucial to understand how to troubleshoot an amplifier when it’s not working. Several things could go wrong, and we will go over some of the most common problems below:

No power: This could result from a blown fuse, inadequate power supply, or a bad circuit board.

No sound: This could be caused by a blown fuse, lousy speaker wiring, or a bad circuit board.

Distortion: This is usually caused by too much power going to the speakers and can damage them. It can also be caused by a damaged output transistor, capacitor, or resistor.

How to Test an Amplifier with a Voltmeter

To test an amplifier with a voltmeter, you must set the meter to measure voltage AC. Most meters have a setting for this.

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Touch the meter’s red lead to one of the speaker terminals on the amp and touch the black tip of the meter to the ground. You should see a reading on the meter.

If the reading is 0, there is no power getting to the amp. If you are unsure what wires go where on your amp terminals and don’t feel comfortable testing it yourself, have a professional test it for you.

If everything looks good with the voltmeter, but there still is no sound coming from your speakers or subwoofers, you may need to replace the amp.

How to Repair Your Amplifier

If something is wrong with the electronics inside an amplifier, testing each part can be tricky and expensive. 

If an amp has power but no sound, it probably needs to be cleaned inside. Dirt and dust can cause interference with the electronics, which causes them not to function correctly. A professional audio cleaner will clean your connections while providing a protective coating that prevents corrosion from

Troubleshooting Common Problems with Amplifiers

If you need to repair your amplifier, then it is possible that several issues caused the problem. The following are some common problems and their solutions.

No power to an amplifier – check the fuse, make sure power is getting to the amp, test with a voltmeter.

Amp not powering on – there is a good chance one or more of the fuses has blown. 

Solution: You should replace the blown fuse with one of the same ratings.

Distorted sound: The most probable cause is a blown output transistor. If you own a multimeter, check for continuity on the speaker connections, there should be none if an output has blown.

Solution: Replace transistors (if possible) or the whole amplifier.

The distorted radio signal can be caused by dirty connectors inside your car’s electronics.

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If you open the amplifier’s cover and see the dust, clean all and especially dirty connectors with a contact cleaner. I use DeoxIT and have to say it works excellent.

No sound from one or more speakers: This can be caused by a blown speaker, lousy wiring connection, or a problem with the amplifier itself.

Solution: Replace blown speakers or wiring, replace the amplifier.

No sound from one speaker or subwoofer – A blown speaker will cause this problem, but a bad connection with the amp can also cause it.

You may have gotten some water in your subwoofer and fried the electronics inside it, which is not easy to fix if you have no experience in electronics.

Solution: Replace the blown subwoofer, replace the amplifier.

8 Steps to Check if Your Amplifier is Working After Applying Fixes

After fixing the issue, you need to recheck to ensure that everything is working correctly.

If weeks have passed since you last fixed your amplifier, but you still hear either distorted noises or no sound at all, then you need to do the following:

Check the Fuse to Make Sure It’s Not Blown

If the fuse is alright, you can check for problems with your amplifier by applying different test signals.

Look at how you can connect stuff up to an amp to know what wires are connected and which test signals to use.

Check the Wiring in an Amplifier

To test your amplifier, you need to have some way of providing a signal to it. You can accomplish this by using a multimeter or wiring an audio source to the amp.

If You’re Using a Multimeter:

  • Set the multimeter to the lowest ohms scale and touch the two probes together. You should get a reading of infinity (∞).
  • Now, touch one probe to the battery’s negative terminal and the other to the car’s metal chassis. You should get a reading of 0. If you don’t, then there is a good chance that your meter isn’t working.
  • Touch one probe to the battery’s positive terminal and the other to a good ground point on the car chassis. You should get a reading of 0.

 If You’re Using an Audio Source:

  • Connect one end of a wire to the left channel output (or any other working channel) of your audio source and connect the other end to the positive terminal of your battery.
  • Then connect one end of a wire to the right channel output (or any other working channel) of your audio source and connect the other end to the negative terminal of your battery.

If you have an amplifier with more than two channels, all you need to do is use the same audio source for the remaining channels.

Test Signals for Amplifier Testing

Now that you have an audio source or a multimeter connected, you need to apply a test signal to the amplifier. The following are some standard signals that you can use:

Audio tone: You can create an audio tone by using an oscillator or another audio source.

Square wave: A square wave can be created using an oscillator or a function generator.

Sine wave: A sine wave can be created using a signal generator or an audio source with a low frequency.

Check for Loose Wires or Burnt-Out Components – Replace the Parts if Needed.

If your amplifier still doesn’t work after checking for loose wires and burnt-out components, then there is a good chance you have an issue with the amp’s circuit board which probably means it will cost more to fix than what it would cost to replace.

You can try taking apart your amp to look at the circuit board, but this is not an easy task, and you may need some help from someone with an electronic experience.

Checking for Voltage Drop

To properly test your amplifier, you need to make sure that the voltage at the amp is not dropping below 12 volts.

You can do this by using a multimeter and setting it to measure DC voltage.

Then, touch one multimeter probe to the battery’s positive terminal and the other probe to any good ground point on the car chassis. You should get a reading of 12 volts or more.

If you get anywhere more minor than this, there is probably something wrong with the power supply, which may mean that your battery isn’t charging correctly and needs to be checked or replaced. 

You can replace the battery yourself by disconnecting your car’s negative terminal from the battery. Still, it would be best to take it to a mechanic to get it replaced since you’re working with high voltage.

Checking for Short Circuits

To check your amplifier’s circuit board and wires, you need to ensure no short circuits inside the amp.

These can be caused by loose connections or damaged wire insulation. 

To do this test, connect one multimeter probe to a good ground point on the car chassis. Then, touch the other probe of the meter to each terminal of the amplifier. You should get a reading of 0 volts.

If you get any other reading, there is a short circuit somewhere in your amplifier, and you will need to find and fix it before continuing with any further tests.

Checking for Open Circuits

Open circuits are caused by damaged wire insulation or broken wires, and they can cause your amplifier not to work correctly. To test for open circuits, follow the steps below: 

  • Connect one probe of the multimeter to a good ground point on the car chassis. Then, touch the other probe of the meter to each terminal of the amplifier. You should get a reading of greater than 0 volts.

If you get any other reading, there is an open circuit somewhere in your amp, and you will need to find and fix it before continuing with testing anything else.

If none of this works, try replacing all fuses you can see, including the one in your car’s fuse box and under the hood. 

If you still have no luck, it may be time to call a mechanic. Mechanics are trained on how to fix electrical issues like this. They probably won’t charge very much for helping out with small things like these (especially if it will save them from doing a more complicated repair later on). 

Another option is taking it into an electronics store and paying them for the help, but you will typically spend at least $50, if not more.

Clean the Connections and Replace All Old Wires With New Ones.

Do this for every solder point of your speaker system. You can ask your peer to help you with soldering, or if you’re feeling adventurous and have some spare cash, you can take it into an electronics store and have them do the repairs for you.

Just make sure that you get some heat-resistant locking pliers to prevent wires from disconnecting again.

Pay someone if you have to, but this is an important step and one that could save your car’s speakers in the future (and possibly even more of your vehicle). It may take a while to finish everything, so be patient.

Test Again Until Everything Is Working Correctly.

You can now test your speakers again. If everything is working correctly, you don’t need to do anything else (unless the wire insulation or connections are still damaged).

If your issue is still there, try checking all car fuses and replace any that have blown out. Also, you may want to check if it’s just a simple fuse or something more serious with the amplifier.

If all of that still doesn’t work, then it may be time to take your car to a mechanic and have them look at it. They will be able to tell you what’s wrong with your vehicle and how much it will cost to fix it.

Is it Expensive to Replace a Car Amplifier?

An amplifier is an essential part of your car audio system, and replacing one can be expensive, depending on how big and powerful the amp is.

For example, a small two-channel amplifier like BOSS Audio Systems CE102 will cost you less than $30, while something more powerful like JL Audio RD400 could cost as much as $500 to replace.

AudioControl LC-5.1300 High-Power Multi-Channel Amplifier with Accubass

Of course, cost also depends on the brand and built quality, so if you are looking for a top-class like AudioControl LC-5.1300, expect to pay accordingly.


These are some of the most common things that can go wrong with your car’s amplifier and how you can fix them.

Car amplifiers can be tricky to set them right, but you should have your vehicle sounding new in no time with these tips.