CONTENTS
- Safety---Safe servicing. Safety considerations with respect to picture tubes. How great is implosion risk? How implosions occur. Skin tension of glass. How to avoid causing an implosion. How to handle picture tubes. Cautions for minimizing implosion injuries. Using safety goggles. Disposing of unwanted tubes. How to deactivate a picture tube. X-ray radiation. Avoiding TV shock. Aquadag grounding strap. Radio shock hazards. Degree of shock. Avoiding tube-caused burns.
- Tube and component damage---Tube mountings. Positioning of rectifier tubes. Preventing damage to low-voltage rectifier. Plate and screen dissipation ratings. Ventilation. Avoiding damage to horizontal output tube. Cautions on high voltage rectifiers. High-voltage lead dress. Protecting c-r tubes. Tube damage due to grid emission. Grid-to-ground resistance. Premature tube failure due to leaky coupling capacitor. Miscellaneous sources of arc-caused damage to tube and components. Series-filament circuits. Cautions on use of tube testers.
- Tube troubles in tv---Localizing defective tube when raster and sound are absent. Raster absent, sound normal. Raster absent, hum in sound. Cathode-to-heater short. Intermittent raster. Excessive warmup time. Size, linearity and brightness troubles. Insufficient width due to tube troubles. Reduced line voltage. Vertical deflection absent. Insufficient height. Intermittent vertical collapse. Vertical shrinking. Increasing height by tube substitution. Vertical non-linearity. Horizontal nonlinearity. Insufficient brightness. Excessive brightness.
- Picture and sound troubles---Pix absent, sound and raster normal. Pix and sound absent, raster normal. Intermittent pix and sound. Pix and sound reception absent on some channels. Receiver inoperative on uhf. Pix missing; sound is strong. Insufficient signal. Snow. Weak uhf reception. Overloading. Negative picture. Poor definition. Resolution troubles. Picture smear. Engraved effect. Ghosts. Buzz. Other sound troubles. Sound absent, pix normal. Weak and/or distorted sound. Noisy sound. Noise drowns out desired sound. Sound and pix do not track.
- Sync troubles---Vertical sync trouble. Rolling due to 6BL7-GT characteristics. Tube substitutions to improve vertical stability in weak-signal areas. Vertical jitter due to lead dress. Vertical blanking bar in pix. Single vertical pix unobtainable. Poor interlace. Horizontal sync trouble. Horizontal sync instability. Horizontal pulling. Horizontal tearing. Horizontal jitter. Symptoms associated with controls. Horizontal sync symptoms. Improving horizontal sync stability. Flashes in picture.
- Interference---TVI. Radiation from horizontal output tube. "Tweets". Barkhausen oscillation. Vertical-line troubles. Vertical lines due to improper lead dress. Vertical white line due to failure of horizontal retrace blanking tube. "Spook" interference. Radiation from audio output tube. "Snivets". Microphonics. Sound in pix. Hum bars in picture and raster. Corona and arcing. Localizing corona. Arcing inside the at. Arcing at metal C-R tubes. Arcing due to improper crt grounding.
- Picture tubes---Bulb and base differences. Aquadag coating. Glass vs. metal tubes. Picture-tube lengths. Electrostatically and electromagnetically deflected picture tubes. Yoke and focus problems. Centering devices. Ion-trap systems. Damage due to misadjusted ion-trap magnet. Testing and repairing picture tubes. Possible troubles in picture tubes. Loss of emission. Rejuvenation. Cathode defects. Gassy tubes. Filament troubles. Heater-to-cathode shorts. Grid-to-cathode short. Magnetized metal picture tube. Universal picture tubes.
- Radio tube troubles---Intermittent filament troubles. Station drift. Receiver volume below normal. Distortion. Hum. Hum due to heater-to-cathode leakage. Modulation hum. Hum due to cathode-to-heater short. Filament-to grid coupling. Tube shields and hum. Lead-dress hum. Socket trouble. Obscure causes of hum. Tube-caused buzz. Oscillation. Micro phonic tubes. Noisy tubes. Tube troubles in portable radios. Avoiding tube damage. Intermittent operation and fading. In-operation. Distortion. Low volume. Miscellaneous symptoms.
- Tube replacements---Precautions in making tube substitutions. Salvaging the diode-triode. Replacing tuner tubes. Improving reception through tube substitutions. Replacing rf oscillator tubes. Video if tube replacements. Sweep and sync tube replacements. Tube design. Horizontal output tubes. Substitution rules. High- and low-voltage rectifier tubes. Replacing Parallel rectifiers. Avoiding needless picture tube replacements. Re-necked picture tubes. Electrostatic-focus picture-tube substitutions. Retaining salvage value of the picture tube. Tube replacement notes.
Introduction:
TUBE faults are, by far, the most frequent ones encountered by the TV-radio technician; he runs into them in perhaps 70% (and quite possibly more) of his service jobs. Even the best service technician not infrequently spends an undue number of minutes in localizing some tube defect; less experienced men may waste one or two hours in tracking down some tube-caused faults. The author recalls a case in which a service technician spent several hours in tracing a condition known as "Christmas-tree effect" to a weak video amplifier tube. It had just never occurred to the man to link this particular cause and effect together. Numerous similar in stances could be cited. This guide is intended to minimize such roundabout troubleshooting.
The reader will find here an organization of TV and radio tube troubles, both familiar and unfamiliar, into a handy form that permits fast reference to needed information. TV-radio service data form a peculiarly elusive body of knowledge in the average technician's mind; information he hasn't used for some time is quite likely to slip away and be missing when it is needed most.
This guide is intended to act as a memory guide with respect to tube troubles when fast refreshing is needed. The author hopes that even advanced service technicians will find material here with which they are unfamiliar.
A guide of this type should prove most valuable for less experienced service technicians and beginners. The outside service technician with a sketchy technical background will find it very helpful; so will the shop owner or manager who wants to train--or increase the efficiency of--a home service technician.
The intent of the guide is not only to speed tube troubleshooting directly--it also aims to do so indirectly, by presenting a wealth of service data about tubes. The author knows of no other book, incidentally, that covers this territory.
The author and publishers acknowledge with thanks the cooperation of the following companies during the preparation of this book: Admiral Corp., DeWald Radio Mfg. Co., Allen B. DuMont Laboratories Inc., Emerson Radio & Phonograph Corp., General Electric Co., Hoffman Electronics Corp., The Magnavox Co., Motorola Inc., Packard Bell Electronics Corp., Philco Corp., RCA, RADIO-ELECTRONICS Magazine, Radio dr Television News, Sylvania Electric Products Inc., Technician, Traveler Radio Corp., Westinghouse Electric Corp., Zenith Radio Corp.
-SOL HELLER
Soft cover design by Muneef Alwan; Cover design of the clothbound edition by Thomas Falletta
Also see:
Air Time--An Intro to Television Broadcasting