Start Grob TV End Chapter Exercise 16
Answers are Underlined
Chapter 16
Television and Video Servicing
16-1
- a. An isolation transformer has separate primary and secondary windings. T
- b. The wider blade in a polarized ac line plug connects to the chassis in receivers with a line-operated half wave rectifier. T
16-3
- a. DMM has higher resistance as a dc voltmeter.
- b. Meter loading decreases the voltage reading.
- c. The external multiplier for a high-voltage probe is 900 MΩ.
16-4
- a. An oscilloscope with a 50 MHz bandwidth must be used for TV servicing. F
- b. The TV switch on an oscilloscope can be set for two cycles of video signal, at either the V or the H scanning rate. T
- c. A dual-beam oscilloscope has a CRT with two electron guns.
- d. A delayed-sweep oscilloscope uses two internal time bases. T
- e. A tuner subber produces the IF output signal. T
16-5
- a. The NTSC color-bar generator produces standard chroma and luminance values. T
- b. The color bars in a gated rainbow pattern differ in hue phase by 30°.
- c. Color bars have the standard amplitude of 75 IRE units.
16-6
- a. The range of the tint control when it can move a color one bar to the left and right is +/- 30.
- b. Which color-difference signal has the same phase as the burst? (B-Y)
- c. Which color bar has the output from a B-Y demodulator? Sixth
16-7
- a. No horizontal output can kill the sound. T
- b. A receiver with current in the ADG coils has AC power input. T.
16-8
- a. Two pairs of horizontal bars are produced by 120-Hz ripple in the video signal. T.
- b. Hum in the sync can cause bend in the picture. T.
16-9
- a. If the anode potential drops a few kilowatts, the raster will be bigger.
- b. A gassy picture tube can make the anode voltage too low.
- c. Blooming in the picture tube indicates a poor HV regulation.
- d. The grounded clip lead should be connected first in order to discharge the high voltage.
- e. The picture tube shows a thin vertical line before the screen goes black. The trouble is in the Horizontal Oscillator.
16-10
- a. Transformer T1 is the horizontal output transformer. T
- b. Conduction in the SCR kills the high voltage. T
16-11
- a. An inexpensive way to obtain a good alignment tape is a copy the manufacturer’s original. F
- b. A large error in the scanner rotational speed makes the picture look as if it were out of horizontal sync. T.
- c. Excessive moisture can trigger the automatic stop in a VCR. T.
16-12
- a. Ina single-tube color camera, the problem of no color can be paused by poor electrical focus. T.
- b. Balancing red, green and blue for color camera is done by pointing the camera at a stair-step reflectance
- chart.
- c. Insufficient beam current in a vidicon causes a low-contrast picture. T.
- d. The standard output voltage from a color camera is 1V p-p.
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