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Amplifier Repair Tutorial
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The information contained in this tutorial is from 20+ years of experience working on amplifiers such as those from Rockford, Sony, Autotek, Coustic, Planet Audio, Kenwood, Pioneer, JVC and just about any other brand sold in the US. This tutorial has information and tips that will help you repair hundreds of different models of amplifiers. It is also interactive (demos allow you to change the input values on various sample circuits and see how the output changes). There are no service manuals (service information provided by the manufacturer for a given model of amplifier) from any company that are even remotely interactive. Since many amplifier manufacturers offer zero tech support (not even schematic diagrams), this may be one of the few sources of information to help you repair some models. For car audio amplifiers, there is nothing else like this at any price.
This tutorial contains a considerable amount of information specifically related to troubleshooting at the component level. It includes commonly used alternate part numbers for the most common semiconductor failures. If you want to get into the repair business, this disc will provide some very important information. If you are already in the repair business and are interested in repairing car amplifiers, this tutorial can help you get started with very little effort. If you are in the repair business, you already know that more and more equipment is disposable (not worth repairing when it breaks). Car audio amplifiers are one of the few money making types of consumer electronics to be repaired.
A note about updates:
I'm continually updating the tutorial (something is added or refined virtually every day). Many times, it's just a few notes or new images. Other updates include entirely new chapters. The discs are not burned until needed. When you purchase the DVD, the tutorial you receive will include all information available at that point in time (4.3+ gigs of information including text, interactive demos, graphics, short video clips of common tasks and photos).
March, 2008 -- Updated!
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Lately, I've been working to make the tutorial more user friendly. Many of the most recent updates involve linking relevant pages to the text. I've also been trying to clarify information to better suit those new to repair work. I use questions from buyers (and others who I help with amp repairs) to make the information easier to understand.
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I've added markers to pages that show you the information you should print and keep handy while working on the first few amps. These 'cheat sheets' will help you troubleshoot the most common faults.
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Of course, I've added new information. New applets, as well as lots of new graphics showing examples of various problems and solutions. Approximately 400 graphics files have been added or modified/improved since the last update. In some cases, I've replaced older, smaller graphics with new or resized graphics. Some of the original graphics were designed when 800x600 was a commonly used screen resolution. The new, larger graphics allow you to see much more detail at higher screen resolutions.
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A new page has been added to help you clean really noisy potentiometers. Many of the potentiometers are very difficult to obtain as replacement parts. This will help you salvage some of the potentiometers that are not readily available. This goes well beyond spraying contact cleaner into the pot and turning it. It also explains how things other than a dirty resistive track can cause problems.
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I've added more information on class D amps. Some of this information covers a relatively common problem with one type of class D driver board. This is a problem that took quite a bit of time to find initially but has saved many hours of wasted time for other amps with similar problems.
September, 2007 -- Updated!
- For many of the amplifiers being produced in China and Korea, the manufacturers will not provide schematics (they probably don't want you to know that they can't/don't design their own amplifiers). Fortunately, MANY of the manufacturers use precisely the same circuits. If you've ever been to the ampguts site, you've no doubt seen how many of the amplifiers use precisely the same board (this is particularly true for class D amplifiers). I've collected several schematics that cover most of the Chinese/Korean amps and I group them together so you can see which schematic to use for a given type of circuit. The schematics won't always match 100% but in most cases, they make it MUCH easier to troubleshoot the circuit.
July, 2007 -- Updated!
- I've significantly expanded the information provided for one of the two most commonly used class D amplifier circuits (multiple manufacturers use the same PWM drive and output circuits - Kicker, Orion, JBL, Memphis...). The information includes waveforms from virtually every point in the PWM generation/output circuits.
- For those with minimal skills when working with metal, I've included an entirely new section. It shows tools (and the use thereof) that are required when there are issues with the heatsink or when you need to produce new clamps (for missing or melted clamps). This doesn't happen often but it's good to know. This is a companion to the MEHSA replacement tutorial I added last month.
June, 2007 -- Updated!
- I've added a page detailing the replacement of the MEHSA insulators if you'd like to do away with them. The section includes relatively detailed instructions on making the replacement clamps. I tell you how to accurately measure the distance between centers for the mounting screws (holes have to be drilled in the clamps). I suggest some free cad software to help you in the process. I even show you the finished clamp on an 800a2. This also comes in handy for amplifiers where someone has broken off a screw in the sink. In this example, they had tried to remove it which made it too much of a mess to try to repair. A new, heavy duty clamp (made to apply sufficient pressure to the transistors adjacent to the missing screw) got the amp back into service reliably.
- I've added at least one example of an amplifier that had a badly damaged board. The repair on it left it stronger than it ever was and there was little evidence that it was so badly damaged. This was one of the times when it was important to have some mechanical aptitude to get the job done.
April, 2007 -- Updated!
- I've added a significant amount of new information about special/unusual resistors and capacitors. This includes information on how to read their values and what the markings mean.
- I've added a page that offers several solutions for customers who repeatedly burn the RCA shield on their head units. Open shields on the signal source can cause some amplifiers to fail. This will save you some headaches with certain types of problem customers.
March, 2007 -- Updated!
- I've added a new page giving suggestions on making ultra reliable wiring harnesses for the workbench. It's vitally important to be able to trust your test equipment. This includes the bench wiring. Some of it takes a beating. The tips I provide will insure that you don't have to continually repair the cables you use repeatedly all day long.
- The 'Terminal Blocks' page has been expanded to show problems and solutions for damaged blocks as well as work-arounds for blocks that use screws that are essentially unavailable. This will be very helpful if you accept one of these amps for repair and the screws are missing or damaged beyond use.
- I've updated/expanded the information on several of the class D troubleshooting pages.
- Of course, I've added new photos of amplifiers that help identify missing or burned components in the amplifiers.
February, 2007 -- Updated!
- I've updated and expanded the page showing how to check most common semiconductors. This includes new graphics and more detailed instructions.
- I've added information on the sizes of the terminal block screws for the most common amps. The information includes diameter, thread pitch and length. For amps that use similar terminal blocks, I've included photos so you can match them up. Many times, the screws used in terminal blocks are not available locally. This information will allow you to order the correct replacement screws the first time (no guessing at the size and thread-pitch).
- I've included the instructions for making jumpers for the JL 500/1 amp. These allow you to separate the two boards so you can check waveforms and voltages on the components between the boards. Without these jumpers, you have to separate the boards, solder a wire to the test point, plug the boards back in and then take the measurements using the jumper wire. The jumpers allow you full access to the area between the boards.
- The power supply troubleshooting flowchart has been expanded. It covers more defects and provides more tips to help make the repair more reliable.
- If you've worked on MTX amps, you've noticed that the power supplies are very different from most other amps. A new section has been added to show the differences (including waveforms). It also tells you how the MTX amps operate differently in the way they switch the PWM drive output on. Much of this information also applies to Sony class D amps as well as some of the Xtant amps.
- In many sections, I simply showed the schematic symbols for various circuits. Now there are more photos of the components on actual circuit boards. For example, there are about 5 different types of voltage regulators used in various amplifiers. For each one, I provide a photo of the regulators in an amplifier. This will help you to more quickly identify the circuits when you're troubleshooting a problem.
- The 'Amplifier Basics' page has been expanded including more detail and graphics to help those who are new to amplifier repair.
- The 'Repair Introduction' page has been expanded. Now there is more information on the ways various components fail and the problems they cause.
- New links have been provided on many pages to help you find the information you need more quickly and more easily.
December, 2006 -- Updated!
- Well over 400 new files and photos have been added or updated since October. The updates on the repair notes include several problems that can be tough to find. At this point, there are more than 3000 photos of amplifier circuit boards (not 3000 different amps). These are very handy when you receive an amp that has missing parts or parts burned beyond recognition. Many manufacturers will not provide any information about their amps so you either have to find another amp of the same model or guess at the values. I've also added two new video clips.
October, 2006 -- Updated!
- NEW I've added a page showing many of the common problems and solutions for one of the most common class D amp designs (used by several different manufacturers).
- NEW More video clips have been added (more than 30 video clips at this time).
September, 2006 -- Updated!
- NEW More information has been added to assist in repairing older ('BBQ' pit style amps). This covers a lot of the other Rockford amps also.
- NEW More video clips have been added.
- NEW A new interactive op-amp demo has been added to help those who don't understand the various op-amp circuit configurations.
August, 2006 -- Updated!
NEW Recently I've been adding small video clips that show common repair procedures. The following is a partial list of the types of procedures shown:
- Replacing surface mount components (transistors, resistors and ICs)
- Removing/replacing spring clamps
- Removing the types of transistors that are soldered to the insulators
- Other miscellaneous, but important tasks
July, 2006 -- Updated!
- NEW I've added a new page dedicated to helping buyers to understand how a scope is used for quick troubleshooting. The page includes notes on the various test points including what they should see and what to look for if the proper signal isn't present.
- NEW More than 300 files added, edited or modified this month alone.
June, 2006 -- Updated!
- NEW I've added a page dealing with repairing amplifiers that have thermal damage to the circuit boards. Many times, the copper foil traces will be damaged when an amplifier fails. This is very common in the power supply section. This new page takes you through one such repair.
- NEW A new page helps you to more reliably repair amplifiers that have physical damage. This page tells you how to perform repairs that will produce very reliable repairs. This is especially helpful for single sided circuit boards.
- NEW I've added a new page that helps you to more efficiently troubleshoot problems in the power amplifier stage of an amplifier. This includes information for troubleshooting inside the feedback loop where discrete differential amplifiers are used.
- NEW An entire page is now dedicated to the replacement of power transistors that are soldered in place. These are used in amplifiers from Rockford, Pioneer and Digital Designs. The page takes you through a repair where the previous repair was not properly performed. It shows you how to prevent making the same mistakes as well as tips to make the repair as reliable as possible.
- NEW There have been updates to both the Equipment and Tech Tips pages. Minor revisions have been made to other pages as well.
March, 2006 -- Updated!
- NEW The tutorial includes relatively high resolution images of the internals of more than 100 amplifiers. The images can be used to determine the values of burned or missing components or simply to help familiarize yourself with the layouts of different amplifiers. According to a search of the folders with amplifier images (I didn't count them), there are more than 1500 large, high quality images (500kB-1MB per image file).
- NEW I've now begun to add waveform images for both the audio and power supply sections of both linear and class D amplifiers. Some of the waveforms are an overlay on the schematic. Others point to points on the circuit board (IC and transistor terminals/pins generally). Most of these are in flash format. This allows me to include many high resolution waveforms. You simply zoom in to clearly see the waveform of interest. There are also waveform images that are named so that you know what they are (those are in the folders of the respective amplifier). There are more than 300 waveform images as of now.
- NEW I've also begun adding more descriptions of repairs and the troubleshooting procedures. Some of the repairs were simple and some were very complex. For those just starting with this type of work, this will be very helpful.
- NEW For those who do not yet have an oscilloscope, I've added images that show the waveform and the equivalent DC voltages (as they would read using a digital multi-meter). I have values/images for all pins of the HIP4080, the TL494/594 and the SG3525. Even if you have a scope, these are helpful to let you determine whether the waveforms you have are correct or not. Most all of the scope images show the vertical amplifier (volts/div) and timebase (time/div) settings so that you now how to set your scope. Some of the images show the entire face of the scope (and all of its controls). Others show the waveform on a scope that displays the values on the CRT.
- NEW I've included more datasheets with suggestions for stocking the most common parts. The datasheets included include power transistors (FET and BJT), op-amps, regulators, muting transistors, driver ICs and more. Nearly 100 are included as of now. These can generally be downloaded but it's quicker to grab them from disc than to find them on the internet.
- NEW A new page helping you to better/more efficiently use your meter when testing components.
- NEW I've added 2 new pages that help those who are completely new to electronics and/or repair work. One includes descriptions of various components including quick-links to more detailed information (also included on the tutorial disc).
July, 2005 -- Updated! I've added more information to help ease newbies into the technical aspects of the tutorial. I've also updated it to include all of the extra material (test questions, applets and demos) that are included on the full version of the site CD.
- NEW Protection Circuit troubleshooting with 4 new interactive demos
- NEW Interactive audio and power supply troubleshooting flowcharts
It contains...
- NEW Troubleshooting basics chapter to help those who are new to electronics including 5 new interactive demos (January 2006)
- NEW Protection circuit troubleshooting with 4 new interactive demos
- NEW Interactive audio and power supply troubleshooting flowcharts
- Audio troubleshooting basics with an image or two of audio waveforms
- Basic circuit diagrams for different types of output transistor configurations
- Class D basics with information about the HIP4080 driver IC including:
- Pin out descriptions
- Typical power supply configurations
- Typical op-amp supply voltages for different types of power supplies
- Drive output diagrams
- Suggestions for setting up a workbench for repairs
- Suggestions dealing with customers and reducing headaches when dealing with them
- Images that show the location of various parts (output
transistors, power supply FETs, rectifiers, thermistors...) on various
amplifiers.
- Tech tips and basic troubleshooting suggestions (more than 80 different tips to help you save time, effort and money)
- Schematic symbols used in amplifier schematic diagrams including:
- Resistors
- Potentiometers
- Diodes
- Bipolar Junction Transistors
- N-Channel Field Effect Transistors
- P-Channel Field Effect Transistors
- Junction Field Effect Transistors
- Suggestions for specific tools (desoldering pumps, irons, screwdrivers...)
- Power supply design/operation basics with actual oscilloscope waveform images
- A very detailed explanation of the most popular power supply driver IC (TL594) including interactive Flash demos showing:
- Comparators
- Error amp input and dead time control
- PWM comparator operation with 3 inputs (all interactive)
- PWM comparator operation with 4 inputs (all interactive)
- Lockout voltage and regulation
- Tips on getting an amplifier's power supply to come on when
the amplifier continually goes into protection (this is very helpful)
- Basic power supply schematics with 3 different types of power supply MOSFET driver circuits
- Information about different comparators used in power supply protection circuits
- Information about thermal protection and the types of devices used in those circuits
- Links to some of the most popular replacement parts datasheets (including some hard to find datasheets)
- Common parts package outlines with pin configurations including:
- TO-218 Transistors
- TO-220 Transistors
- TO-92 Transistors (both Japanese and American types)
- 14 Pin quad op-amp
- 8 Pin dual op-amp
- 9 Pin dual op-amp with power feed-through circuit
- Circuit board layout information including:
- Foil layout and component orientation
- Silk screen definitions
- Internal block diagrams of the 2 most popular op-amp configurations
- Common op-amp circuits used as buffers, inverting amplifiers and non-inverting amplifiers
- Information on negative feedback circuits using discrete differential pairs or op-amps
- Information about 4 different types of voltage regulators found in amplifiers including:
- Simple shunt regulators
- Current boost shunt regulators
- Fixed regulators
- Resistor-programmable regulators
- Basic description of 2 types of muting circuits
- Information about the generation of higher_than_rail drive voltage for common collector amplifiers
- Notes on the equipment needed for repairs
- Power supplies (pictures of both linear and switching power supplies)
- Dummy loads
- Voltmeters - The following DMMs are shown on the tutorial.
- Fluke 77
- Fluke 79
- Fluke 27
- Fluke 11
- Fluke 112
- Oscilloscopes:
- In the tutorial, I cover a significant number of oscilloscope features and give quite a few suggestions for buying a used scope. As of now, virtually every feature that you'll need is shown and explained. I even show some advanced features that are not necessary but are available. Some of the scopes were purchased on eBay and for those scopes, I tell you approximately what they cost and/or what you can expect to pay.
- I've also included high resolution images of the internals of more than 100 amplifiers (3000+ images). For someone who isn't familiar with the various amplifiers on the market, the photos will show them what they might encounter. Many times I use them as a reference. If an amp has missing components or components that are burned beyond recognition, I can refer back to the photos to determine what I need to repair the amp. Even if the exact amplifier that you need isn't available, there may well be one that's similar enough to be of help. There are many amplifiers that use very similar circuits. Many times, the only difference is the way it's laid out on the board. The photos generally include one overall image of the amplifier. Then each section (power supply drive, audio drive, preamp...) is photographed to allow you to see the fine details. In general, the resolution is high enough so that the values of tiny surface mount components (often only 0.05" wide) can easily be read.
- The cost is $49.95 plus shipping via USPS Priority mail ($6) within the US or via Priority Mail International ($15) for those buyers outside of the US.. Since the average labor for repair is ~$40-$70, it will take very little time to recoup the cost of this tutorial. For more info, Email me.
Note:
If you feel more comfortable buying on eBay, I typically have the discs for sale there. Search eBay for 'amplifier repair tutorial'. My eBay user name is perrybabin. If you see another seller selling a copy of the tutorial, it's an older version. If I don't have the tutorial listed when you're ready to purchase it, email me and I'll list one.
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Important!
Virtually all orders will go out on the next business day after I receive the order. All orders should be received within 4 business days. If you don't receive the tutorial within 5 business days (within the US), please email me. Sometimes, the notification from PayPal is not delivered to my inbox as it should be and I don't know the order has been placed. If you want to make sure that I received the order, feel free to email me.
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If you're using Internet Explorer and have trouble with PayPal 'timing out', try downloading the Firefox browser.
All prices on this page refer to US dollars.
Notes:
- To those who purchased the tutorial and want updates, email me and, if I can confirm that you've purchased a copy of the tutorial, I'll send you the latest version on disc for $10US ($20US outside of the US). Due to the complexity of the directory structure, the lack of computer skills and the size of the files, email updates are not feasible.
- If you
place the order on a Friday or on the weekend, it will typically be
Monday afternoon before I mail the discs. If there is a long holiday
weekend (i.e. Wednesday-Sunday), it may be as long as 5 days before I
can mail them. Otherwise, I almost always get discs out on the next
business day.
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Please note that THIS IS NOT A VIDEO. This tutorial must be used in a computer with a working DVD drive that can read burned DVDs.
The new video clips are in .avi format. They are encoded using the DIVX codec. If your computer doesn't currently have the codec, you must download the codec from the divx.com web site. The videos are highly compressed so they require a relatively fast computer to view them. If you have a gaming computer, it will easily be able to view them smoothly. If your computer is slower than a 2GHz Pentium, you may have problems viewing them.
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