July 1966 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
Very few people these days
would have any clue as to the causes of the CRT-type TV picture problems shown here -
I certainly don't, even after looking at the answers (except for #4, which is pretty
obvious given the choices offered). What I can claim is to have likely seen each one
of those types of issues with all the cheap TV sets I've owned (especially #9). My
current 26" LCD television (I only own one TV), which is ten years old this year, is
still working fine and never displays any of those funny patterns. In the days of the
Macs TV Service Shop stories, survival in the business depended on technicians being
able to quickly diagnose and repair televisions and radios based on knowledge learned
while attending the school of hard knocks. Of course success at servicing modern
equipment sometimes requires extraordinary measures, but built-in test and diagnosis
is part of many electronic systems today. Even your car has an
port for plugging a computer into to get a readout of hundreds of parameters and
potential problem causes.
TV Trouble Quiz
By Robert P. Balin
To be successful in TV servicing, you must be able to interpret the various trouble
symptoms that show up on the TV screen. Test your skill by matching the common troubles
illustrated below (1-12) with their listed remedies (A-L).
A) Adjust deflection yoke or ion trap.
B) Replace phase detector.
C) Adjust automatic frequency control (AFC).
D) Replace horizontal output tube.
E) Adjust height control.
F) Replace vertical oscillator/amplifier.
G) Replace deflection yoke.
H) Check horizontal output tube for Barkhausen oscillation.
I) Replace low-voltage rectifier.
J) Check tubes in video circuits for filament-to-cathode short.
K) Replace sync separator/amplifier.
L) Replace r.f. amplifier in tuner.
TV Trouble Quiz Answers
1 - G) This keystoning effect may be the result of a short in the horizontal winding
of the deflection yoke, or a short in the balancing capacitor across the winding.
2 - C) Slanting bars that change in number, width, and slant angle as the a.f.c. coil
is adjusted are the result of the horizontal oscillator operating off frequency.
3 - A) Neck shadows are produced by the deflection yoke being positioned too far back
on the neck of the tube. They are also produced by an incorrectly positioned focus coil
or ion trap.
4 - F) A horizontal line across the face of the picture tube is an indication of no
vertical deflection. This may be caused by failure of the vertical oscillator/amplifier
tube, vertical output transformer, or other components in the vertical section.
5 - K) When the picture wobbles from side to side while rolling slowly from top to
bottom, the indication is a loss of synchronizing pulses. This is usually caused by a
defective sync clipper or sync amplifier tube, or failure of some other sync component.
6 - J) This dark bar is produced by 60-cycle hum in the video signal. It usually results
from a filament-to-cathode short in one of the i.f., r.f., or video amplifier tubes.
7 - E) Elongation of the bottom portion of the picture is usually caused by an improperly
adjusted height (size) control. This control also has a slight effect on the top portion
of the picture during adjustment.
8 - I) A picture having insufficient height and width (and usually poor brightness,
focus, and sync) is usually caused by low B+ voltage. Try a new low-voltage rectifier.
9 - L) A weak r.f. amplifier tube, as well as a poor antenna, will usually produce
an abundance of snow in addition to a weak, washed-out picture.
10 - D) A picture which fills out completely at top and bottom, but which shrinks
at the sides, can be traced to a weak horizontal output tube. Low line voltage - during
peak evening hours - can also cause a similar effect.
11 - H) Beadlike, black vertical lines on the left-hand side of the picture tube are
usually due to what is generally known as Barkhausen oscillation, which takes place in
the horizontal output tube. Sometimes, mounting a small magnet on the tube will cure
12 - B) Loss of horizontal sync, as evidenced by this split image, can be caused by
an incorrect phase relationship between the horizontal sync pulses and the horizontal
oscillator output. Try changing the phase detector.
Posted April 20, 2018
Popular Electronics published many quizzes over the years
- some really simple and others not so simple. Robert Balin created many of the quizzes.
This is a listing of all I have posted thus far.
- Diode Function
Quiz - August 1965
- Diagram Quiz, August
- TV Trouble Quiz,
- Electronics History Quiz,
- Scope-Trace Quiz,
Circuit Analogy Quiz, April 1973
Your Knowledge of Semiconductors, August 1972
- Ganged Switching
Quiz, April 1972
- Lamp Brightness
Quiz, January 1969
- Lissajous Pattern Quiz, September 1963
Quizoo, October 1962
- Electronic Photo Album Quiz, March 1963
- Electronic Alphabet Quiz, May 1963
- Quiz: Resistive?
Inductive? or Capacitive?, October 1960
- Vector-Circuit Matching Quiz, June 1970
Quiz, September 1961
- RC Circuit
Quiz, June 1963
- Diode Quiz,
- Electronic Curves Quiz, February 1963
- Electronic Numbers Quiz, December 1962
- Energy Conversion Quiz, April 1963
Function Quiz, June 1962
Factor Quiz, November 1966
Math Quiz, November 1965
- Series Circuit Quiz,
Electrochemistry Quiz, March 1966
- Electronic Analogy
Quiz, November 1961
Coupling Quiz, August 1973
- Electronics Analogy Quiz, August 1960
- Audio Quiz,
Unit Quiz, May 1962
Capacitor Circuit Quiz, June 1968
- Quiz on AC Circuit Theory, December 1970
- Magnetic Phenomena Quiz, February 1962
- Electronics Geography Quiz, April 1970
Electronic Menu Quiz, August 1963
- Electronic Noise Quiz, August 1962
- Electronic Current Quiz, October 1963
- Electronic Inventors Quiz, November 1963
Function Quiz, January 1962
- Electronic Measurement Quiz, January 1963
Tube Quiz, February 1961
- Kool-Keeping Kwiz, June