Finding Parts for Restoration of Old TV Sets
Restoring an old TV set requires replacing many parts. Some, like resistors and capacitors, are easy to find. Others, like tubes, can be found, but sometimes require searching. And a few, like pre-1945 picture tubes, are impossible to find.
Here is how we go about finding the parts we need to restore our old sets.
Resistors. For postwar sets, I like to use the old carbon composition resistors that were common in the 40s and 50s. They are often available on Ebay, and some antique radio supply companies sell them. Fortunately, most resistors are good in old sets. Another source is to cut them out of junk sets.
Prewar sets are more difficult. In order to retain the original appearance under the chassis, old style resistors are needed. Occasionally a collection appears on Ebay. Auctions of radio/TV shops that are going out of business are also a good source, as are antique radio swap meets.
Capacitors. For postwar sets, modern capacitors can be purchased at any electronics supply company. Electrolytics can be installed under the chassis, with the original can left in place to maintain the appearance of the set.
For pre-1945 sets, I rebuild the old housings of paper capacitors. Modern capacitors are smaller and almost always fit inside. For electrolytics, the same is true. You can also buy custom made multi section electrolytics from DH Distributors (888-684-0050).
Wire. In postwar sets modern plastic wire can be used. A good source is auto supply stores.
Prewar sets often have rubber wire, which deteriorates. Modern plastic wire looks similar. Several antique radio parts suppliers sell cloth covered wire in different colors.
Tubes (Valves). Vacuum tubes (valves) are readily available from a number of sources at good prices.
Picture Tubes. CRTs are becoming a problem for postwar sets. There are still some good 10BP4s and 12KP4s out there. 7JP4s, used in all the 1948-49 7 inch sets, are getting hard to find, but there are still lots of old junker sets, some of which have good tubes.
Prewar CRTs are a different story. They are made of Pyrex glass, which has a much higher melting temperature. Spares are impossible to find. There have been a couple of successful rebuilds, but they are complicated and risky. A new stem made of modern (low temp) glass is bonded to a tube of medium temp glass, then that is bonded to the Pyrex. The cost of doing this is high - $700 or more. I have one tube at a rebuilder now, since it is bad and I have no other way of getting the set working. The good thing is that a high proportion of pre-1945 tubes are good, since they weren't used much before the war (only a couple of hours of TV broadcasting a day), they weren't used much during the war (even less programming), and after the war the technology was so much better that most sets were replaced.
As for color tubes, the 15GP22, used in the first color sets, has a leakage problem between the glass and the metal faceplate. About 95% of them are full of air. There are about 70 CT-100s out there we know of, and only a couple of dozen good tubes. A couple of collectors are working on rebuilding them - they have found someone to rebuild the guns, they have found a replacement stem, and are close to trying a rebuild. If this doesn't work, the days of working 15 inch sets are numbered as the old tubes die.
As of now, the only CRT rebuilder is RACS in France. They are expensive, and you have to pay shipping both ways. If you have a prewar tube or color tube, you might consider it.
Transformers. Replacements are available for most postwar vertical (frame) oscillator and output, audio, and flybacks (line output transformers) from several sources. Power transformers are more difficult to find. You may be able to find a junk set with a bad cabinet and salvage the transformer. Otherwise, rewinding (at a cost of about $250) is the only option.
Prewar transformers must be rewound. In most cases, this can be done. However, sometimes the cores are too badly damaged. And some high voltage (EHT) transformers used very fine wire sizes, which rewinders can't work with. New transformers can be built, but they are usually not the exact size and appearance.
Knobs. Knobs for postwar sets can be found at antique radio swap meets, and from Dave Frush.
Hot glue sticks in many colors, useful for rebuilding capacitors and transformers, are available from glu-stix.
Antique Radio Classifieds is a good place to advertise for hard to find parts.
Here is a list of some of the sources of parts we have found. You should also check our classified page for other items. The museum also sells tubes and has a stock of flybacks, yokes, transformers and coils.