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 might even learn something about one of our century's key technologies.

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

Where can I find someone to fix my radio?

You might find someone simply by checking in the Yellow Pages or phoning local electronics repair shops. You can also try contacting the nearest radio/TV collector club for a recommendation. Naturally, it's preferable to find someone within driving distance, to avoid the cost and risk of shipping your item long distances.

The Antique Radio Classified website has a list of clubs throughout the world. The print version of ARC magazine also carries ads for repair shops and other services; you can get a free sample copy of ARC magazine upon request. Finally, if you search for a phrase such as "vintage radio repair" on a service such as Google or Bing, you can find repair shops that advertise on the Internet, although these 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 Books for Radio Collectors. Your public library may have these, or they can be ordered from Antique Radio Classified, amazon.com, or your local bookstore.

Many other out-of-print repair books can be found through used-book sources, including eBay. If you get a good repair book, you can basically skip the rest of this page. The book will cover the same ground in more detail.

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 injury or death. 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.

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

It's a good idea for beginners. Radios can be repaired using the general techniques and information given in repair books, but many problems require specific information, and the schematic may include other useful facts, such as the date of manufacture. 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.

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 one tool you can't do without is a small, pencil-type soldering iron, available at stores such as Radio Shack. You may already own the other gear you'll need—a couple of screwdrivers (Phillips and normal head) in different sizes, a small adjustable wrench, pliers (regular and needle nose), wire cutter, and a small knife for stripping insulation from wire.

The most useful piece of equipment is a multi-tester, a small device that measures voltage and resistance. You can get one for around $25 at Radio Shack and many other sources.

If you do frequent repair work, the next most useful item is a signal generator, a device that can generate audio and RF (radio frequency) signals at various frequencies. By injecting a known signal into various stages of the radio's circuit, 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 that part of the radio. A signal generator is also essential for aligning the radio, although that procedure is often not necessary.

Do I Need to Buy a Tube Tester?

Many people ask me whether they'll need a tube tester. The answer is no, for a beginner. Tubes are pretty reliable, in the first place, 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 plays better. Conversely, you can put a suspect tube into a radio that already works, to see if the performance changes.

The same is true of other equipment such as oscilloscopes. If you have one, it can be handy on occasion, but if you don't, there's often another way to skin the cat. It's amazing what a skilled repair person can do just by looking, listening, substituting components, and making measurements with the multi-tester.

How can I refinish the cabinet?

Refinishing wooden radio cabinets is no different than refinishing other wooden objects. My favorite book on wood refinishing is The Weekend Refinisher by Bruce Johnson. For more details, see Books for Radio Collectors.

This website's Restoration section also provides specific information about refinishing various types of cabinets.

My preference, which is shared by most collectors, is to restore wooden objects without making them look "brand new" or erasing all evidence of age and use. If you strip or sand a radio 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 always start out 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. Avoid solvents, especially when working with an unknown modern plastic. Nothing is more disheartening than watching your newfound treasure start to dissolve under your fingertips! The strongest cleaner that I use for cleaning stubborn grime is window cleaner such as Windex.

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 does a fine job on faded old 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 stick to soft cloths and elbow grease.

Cracks in Bakelite and plastic cabinets be reglued 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 probably to watch over the shoulder of an experienced repairman at work. If you join a local collector's club, perhaps you can find someone willing to give you some pointers.

Our Restoration section contains many articles on restoring specific radios, including tabletop, console, cathedral, and tombstone models, as well as communication receivers. These articles contain all sorts of tips and practical advice about repairing electronics and refinishing cabinets.

A good book on radio repair is invaluable. As mentioned earlier, our books page has several to recommend.

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 help you learn 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.

©1995-2014 Philip I. Nelson, all rights reserved