How can I fix my old radio?

Hardly a week goes by without somebody sending me a message like this:

Help, Phil! I just bought a Schmidlap 357 and it looks really great. But when I turn it on, it just makes a loud buzz (or doesn't make a sound, etc.) What should I do??

If you're in this position, here are some answers to help you get started.

Should I fix it myself, or hire someone to do it?

You don't need advanced electronics knowledge to fix most old radios. Tube-powered radios are simple in comparison to modern electronics. Most were built to conventional designs and they use replacement parts that are still readily available. Fixing old radios can be an enjoyable hobby in itself and you can also learn about a key technology of the modern era.

On the other hand, working on any electrical equipment can pose a danger of electric shock. And botched repairs can make a problem worse, if you're careless. If you've never done such work, and you're not interested in learning how, it's best not to poke around blindly.

Where can I find someone to fix my radio?

It's preferable to find a repairman within driving distance, to avoid the cost and risk of shipping your radio long distances. Start by contacting a radio/TV collector club in your area for a recommendation. Even if the nearest club isn't next door, they might know someone closer to you. The Antique Radio Classified website has a list of clubs throughout the world.

If you do an Internet search for a phrase such as "vintage radio repair,", you can find repair shops that advertise, although they may be located far from where you live.

Is there a book that I can read?

Yes! Some excellent radio-repair books are listed on my page Antique Radio/TV Books. Your public library may have these, or they can be ordered through a local bookstore or online. Many other out-of-print repair books can be found through used-book sources.

Are parts still available?

Yes. Commonly needed electronic components are readily available. See my Parts page.

What skills do I need?

For the most common repairs, you need to be able to read and to do simple soldering. SAFETY WARNING: You also need to know how to work safely around electricity. Old radios carry high-voltage current that can cause serious injury if you're careless. The repair books explain how to do this work safely. Never stick your hands (or anything else) inside an old radio if you don't know what you're doing. And keep one hand in your pocket whenever you touch the probe of a test instrument to a chassis that's powered up.

Do I need to get a schematic diagram before I start?

Yes, especially if you're a beginner. Radios can be fixed using the general methods given in repair books, but many problems require specific answers, and the schematic may include other useful info, such as voltage and resistance charts for your radio.

Schematics for US and Canadian radios typically cost a few dollars and can be obtained from the sources in my Parts page. You can obtain many free schematics by downloading from Nostalgia Air or visiting the reference desk at a decent-sized public library. Sams service manuals can also be purchased directly from Sams.

Do I need to replace all of the tubes?

No! A common misconception about radio repair is that you should start by replacing tubes. Like a light bulb, a radio tube is vacuum-sealed; it doesn't deteriorate from simply sitting around. You don't need to replace a tube unless you have some evidence that it has failed. Other components, such as capacitors, are more common causes of trouble than tubes.

What tools and equipment do I need?

The most essential tool is a soldering iron or soldering gun, available from many sources. You'll also need a roll of electrical solder, of course. I have used this gun and iron to restore many sets; both came from garage sales:

You may already own the other small tools you'll need: a few screwdrivers (Phillips and normal head) in different sizes, a small adjustable wrench, pliers (regular and needle nose), wire cutter, a knife for stripping insulation from wire, and the like.

In this photo, the red bulbous object is a "solder sucker," used for removing excess solder from old joints. The tool shaped like a dental pick is a stainless-steel hobby pick, handy for removing snipped pieces of wire from a solder terminal. The small metal alligator clips are used as heat sinks; you can clamp them onto the lead near a delicate component, to prevent overheating while it's being soldered.

Speaking of clips, you'll also want to get (or make) a few clip leads like these, to make temporary connections on your chassis for test equipment, and so on:

Beyond hand tools, the most often-used piece of equipment in any restorer's workshop is a multimeter, a small device that measures voltage and resistance. Multimeters are available from many sources. For about $25, you can find one that gets the job done and lasts for years. Here is my everyday multimeter:

This modern Fluke meter has a digital numeric readout. In a few cases—notably, aligning radios and TVs—it's a little easier to use an analog meter, which displays a value with a needle on a scale; when you're turning an adjuster back and forth, seeking a peak point in a range, it's easier to watch a swinging needle than to decipher a changing stream of digits.

You can often find used meters at a radio/TV swap meet or flea market. These meters may be quite cheap, but keep in mind that a vintage (say, 50-year old) meter may itself require restoration, like any other old device. The next photo shows my Triplett 630-NA meter, a $20 swap meet find:

If I were just starting out, I'd buy a new multimeter: something more modern than the Triplett and less pricey than the Fluke.

What equipment is nice, but not necessary?

Beyond a multimeter, there are a few pieces of test equipment that are occasionally nice to have, but not vital for a casual restorer. These include signal generators and tube testers.

Signal Generator

For frequent repair work, the next most useful item after a multimeter is a signal generator, a device that can generate audio and RF (radio frequency) signals.

Signal generators are useful for diagnosing troubles. By injecting a known signal into various stages of a radio or TV's circuitry, you can zero in on the source of a problem. For instance, if you inject an audio signal into the audio output stage and no sound comes out of the speaker, you know there's a problem in the audio output section.

A signal generator is also useful for realigning radios and TVs, although that specialized procedure isn't always necessary.

Here are two of my signal generators: a simple "service grade" EICO 324 and a fancier (and much pricier!) "laboratory grade" HP 8660C:


If I were starting out, I'd buy a new signal generator with features like the EICO 324. A Rolls Royce-quality device like the HP 8660C is overkill for a casual restorer.

Tube Tester

Many people ask me whether they'll need a tube tester. My answer is no, for a beginner. Tubes are comparatively reliable, and there are other ways to check them.

My article First Steps in Restoration explains how to perform a simple dud/not-dud test on a tube using an ohmmeter. You can also substitute a known-good tube in place of a suspect tube, to see if the radio or TV plays better. Conversely, you can put a suspect tube into a radio or TV that already works, to see if the performance changes.

If you restore more than a handful of sets per year, a tube tester may be worth having. These photos show two of my tube testers, a vintage Precision 10-12 and a modern Sencore TC-162 "Mighty Mite":


The Mighty Mite is my everyday tester for small tubes. The Precision can check certain long-obsolete tubes that the Sencore can't handle, so I might haul it out once or twice a year for those cases.

No tube tester is infallible, not even the costly ones. Simple emission-type testers like mine are mostly good for culling out very weak (or dead) tubes when you first purchase a set. Fancier mutual conductance-type testers can check more tube characteristics, but they don't necessarily tell the whole story. Sometimes a tube that looks "weak" on a tester will perform just as well as a brand-new tube in a particular circuit. And certain tube functions, such as oscillation, can't be judged by any tester.

Other Test Equipment

I own other, more specialized pieces of test gear, such as capacitor testers, an oscilloscope, and so on. You can read about some of them in the Miscellany section of our Gallery. Each has its place, but none of them is used very often.

If you're a beginner, I'd advise against loading up with a bunch of test equipment that you might rarely use or that you might find frustrating. Some devices, like an oscilloscope, are somewhat complicated and demand their own learning curve. It's amazing what a savvy restorer can accomplish using only a multimeter, and (perhaps occasionally) a signal meter. If you're only going to buy one or two pieces of test equipment, I'd lean toward buying new things rather than vintage gear, which may itself need restoration before it's useful.

How can I refinish the cabinet?

Refinishing wooden radio/TV cabinets is no different than refinishing any wooden furniture. My favorite book on wood refinishing is The Weekend Refinisher by Bruce Johnson. For more details, see Antique Radio/TV Books.

In this website's Restoration section, you'll find articles describing how I refinished various types of cabinets.

My preference, which is shared by many collectors, is to restore wooden objects without making them look "newer than new" or erasing all evidence of age and use. If you strip or sand an antique cabinet down to bare wood, you may destroy its collectible value, along with its character. The same goes for applying non-authentic finishes, such as glossy polyurethane. The Weekend Refinisher explains how to detect what finish is on a piece and restore it authentically.

Restoring Bakelite or plastic cabinets is mostly a matter of cleaning and polishing. I recommend starting with the gentlest possible means and materials and resorting to stronger methods only if necessary. I begin with warm, soapy water, some clean, soft cloths, and a soft toothbrush for the small crannies. Cotton Q-tips and round toothpicks also come in handy for tight spots. Beware of powerful solvents, especially when working with an unknown modern plastic. Nothing is more disheartening than watching your newfound treasure start to dissolve under your fingertips! For everyday cleaning, I use nothing stronger than Windex or isopropyl alcohol (rubbing alcohol).

For cabinet polishing, I prefer Novus Plastic Polish, grades #1 and #2, available from Antique Electronic Supply. Novus polish is gentle enough to safely polish the most delicate plastic dial covers, yet the #2 grade works on Bakelite, too. Other collectors polish with various substances, such as very fine-grade automotive rubbing compound, power buffing wheels, and so on. Some collectors wax Bakelite cabinets after polishing, but I've not found that worth the bother, if you've done a good job of polishing. Be patient and stay with soft cloths and elbow grease.

Caution: the shiny surface layer of Bakelite is quite thin; if you polish too hard with harsh abrasives, you'll dig down into the pulpy underlayer of the Bakelite, which nothing will make shiny again. If your cabinet is damaged from sanding or too-harsh polishing, the only remedy is to repaint it.

Cracks in Bakelite and plastic cabinets be re-glued with cyanoacrylate ("crazy glue") if the break is clean. Larger defects in a plastic cabinet can be patched with a product called "Plas-T-Pair," available from Antique Electronic Supply. Larger breaks in a Bakelite cabinet may be harder to repair, although I have heard of people patching them with a mixture of ground Bakelite and some sort of glue.

What's the best way to learn?

The best learning method is to watch over the shoulder of an experienced repairman. If you join a local radio/TV collector's club, you might find someone willing to give you some pointers.

Our Restoration section has many articles on restoring specific radios. These articles contain all sorts of tips and practical advice about repairing electronics and refinishing cabinets. Books, as mentioned earlier, are another excellent resource.

Be sure to check out the the Antique Radio Forums website discussions. Browsing these forums will uncover a wealth of information about restoration techniques, and you can also ask forum members for advice about your project.

Again, if you're a complete novice in electronics, I recommend practicing on a junky radio before you tear into your treasured antique. A visit to the local thrift store may provide a suitable tube-powered patient for only a few dollars. It won't be exactly like your "real" radio, but the techniques that you learn will be generally applicable. Practicing on a junker will tell you whether you like this activity, and you can make those inevitable beginner's mistakes on a set that doesn't have great emotional or monetary value.

Have fun!

©1995-2018 Philip I. Nelson, all rights reserved