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Old 12-30-2010, 12:46 AM
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Jeffhs Jeffhs is offline
<----Zenith C845
 
Join Date: Feb 2003
Location: Fairport Harbor, Ohio (near Lake Erie)
Posts: 4,035
The first thing to do with a TV this old, as anyone in this forum will tell you, is to recap it (meaning to replace the old wax and paper capacitors), or at very least replace the filter capacitors in the low-voltage power supply; failure to do this may and likely will severely damage or destroy the power transformer and/or other parts of the set if it is powered on with old and almost certainly defective filters. If you do not know what I am talking about, turn the set over to a pro and have them restore the set for you. There are very high voltages inside a television set, which can be lethal if you do not know what you are doing. The CRT (picture tube) in all televisions, for instance, has at least 16-18 kilovolts (thousands of volts) on what is called the second anode; the connector for this is on a red wire coming from a part of the TV called the high-voltage cage, located on the chassis. This cage contains the high-voltage rectifier and the flyback transformer; again, if you don't know what I'm referring to, keep your hands out of there. This cage is where the 16,000-18,000+ volts of high voltage for the picture tube is produced, and it can kill. I don't recommend you do this, but if you take the high-voltage connector off the picture tube for any reason (it will be connected to a small well on the right or left side of the bell of the tube), be sure to discharge the tube, and the connector itself, to ground. This will discharge any remaining high voltage on the tube and in the high-voltage cage (in the latter very high voltages are stored in what is known in very old TVs as a doorknob capacitor, so named because of its resemblance to, yup, you guessed it, a door knob); then and only then will the set be 100 percent safe to work on.

Do not try to work on this or any television with the set plugged in; this is an accident waiting to happen if you don't know what you are doing. All televisions made until about the late 1970s have interlocks on their back covers; these are not to be defeated or otherwise tampered with under any circumstances, unless you know exactly what you are doing. Decades ago there were such things as "cheater" cords available, to allow a serviceman to operate the TV with the back off, but these cords are very difficult to find these days since most sets made in the last 30-35 years have their AC cords wired directly into the set itself (this is known as "hard wiring" the cord into the television's works), and are not removable. These TVs are not to be worked on by anyone other than an experienced service person, as the same lethal high voltages I referred to above are in the new sets as well as the older ones. Besides, there are no user-serviceable parts in modern televisions, so it is pointless for anyone other than a qualified technician to take the back off almost any set made from the '80s to now, and beyond.
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Jeff, WB8NHV

Collecting, restoring and enjoying vintage Zenith radios since 2002

Zenith. Gone, but not forgotten.
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