23.8) Vertical squashed

This is a vertical deflection problem - possibly a bad capacitor, bad

connection, flyback/pumpup diode, or other component. None of these should

be very expensive (in a relative sort of way).

If the symptoms change - particularly if they become less severe - as the set

warms up, a dried up electrolytic capacitor is most likely. If they get

worse, it could be a bad semiconductor. Freeze spray or a heat gun may be

useful in identifying the defective component.

It is often easiest to substitute a good capacitor for each electrolytic in

the vertical output circuit. Look for bad connections (particularly to the

deflection yoke), then consider replacing the vertical output IC or

transistor(s).

A defective deflection yoke is also possible or in rare cases, a bad yoke

damping resistor (e.g., 500 ohms, may be mounted on the yoke assembly itself).

The following are NOT possible: CRT, flyback, tuner (except for the famous

RCA/GE/Proscan or Sony models where the controller is at fault - see the

sections on these specific brands). I am just trying to think of really

expensive parts that cannot possibly be at fault :-).

Note that some movies or laser karaoke discs are recorded in 'letterbox'

format which at first glance looks like a squashed vertical problem. However,

the picture aspect ratio will be correct and turning up the brightness will

reveal a perfectly normal raster above and below the picture.

 23.11) Single Horizontal Line

CAUTION: To prevent damage to the CRT phosphors, immediately turn down the

brightness so the line is just barely visible. If the user controls do not

have enough range, you will have to locate and adjust the master brightness or

screen/G2 pots.

A single horizontal line means that you have lost vertical deflection.

High voltage is most likely fine since there is something on the screen.

This could be due to:

1. Dirty service switch contacts. There is often a small switch on the

located inside on the main board or perhaps accessible from the back. This

is used during setup to set the color background levels. When flipped

to the 'service' position, it kills vertical deflection and video to the

CRT. If the switch somehow changed position or got dirty or corroded

contacts, you will have this symptom. Flip the switch back and forth

a couple of times. If there is some change, then replace, clean, resolder,

or even bypass it as appropriate.

2. Bad connection to deflection yoke or other parts in vertical output

circuit. Bad connections are common in TVs and monitors. Check

around the pins of large components like transformers, power transistors

and resistors, or connectors for hairline cracks in the solder. Reseat

internal connectors. Check particularly around the connector to the

deflection yoke on the CRT.

3. Bad vertical deflection IC or transistor. You will probably need

the service manual for this and the following. However, if the

vertical deflection is done with an IC, the ECG Semiconductor

Master Substitution guide may have its pinout which may be enough to

test it with a scope.

4. Other bad parts in vertical deflection circuit though there are not

that many parts that would kill the deflection entirely.

5. Loss of power to vertical deflection circuits. Check for blown

fusable resistors/fuses and bad connections.

6. Loss of vertical oscillator or vertical drive signals.

The most likely possibilities are in the deflection output stage or

bad connections to the yoke.

 23.17) Vertical foldover

The picture is squashed vertically and a part of it may be flipped over and

distorted.

This usually indicates a fault in the vertical output circuit. If it uses

an IC for this, then the chip could be bad. It could also be a bad capacitor

or other component in this circuit. It is probably caused by a fault in

the flyback portion of the vertical deflection circuit - a charge pump that

generates a high voltage spike to return the beam to the top of the screen.

Test components in the vertical output stage or substitute for good ones.

  23.18) Comments on vertical problems

(From: Bert Christensen ([e-mail])).

As a general rule, vertical faults can be divided into two types: ones that

cause geometric distortion (a circle will not be round) and those that simply

black out a portion of the screen. The former are faults in the vertical

oscillator, drive, or output stages. The latter are blanking faults. Blanking

faults are almost always caused by electrolytic capacitors changing value and

thereby changing the timing of the pulses which blank the screen during

vertical retrace. In other words, the pulses are turning off the video signals

at the wrong time.

The most common true vertical fault is geometric distortion and a foldover of

white lines at the top of the screen. This is almost always caused by the

electrolytic capacitor on or near the collector of the vertical output

transistor or part of the IC which has the supply voltage (B+) on it. In the

old tube days, the general rule was that bottom distortion was in the cathode

of the output tube and distortion at the top was caused by a fault in the

drive circuit.

 21.3) Focus adjustment

On a decent TV, you should be able to make out the individual scanning

lines. If they are fuzzy, especially in bright areas, then focus may need

to be adjusted.

The focus pot is usually located on the flyback transformer or on an

auxiliary panel nearby. Where there are two adjustment knobs on the flyback

transformer, the top one is generally for focus and the bottom one is for G2.

The focus wire usually comes from the flyback or

the general area or from a terminal on a voltage the multiplier module

(if used). It is usually a wire by itself going to the little board

on the neck of the CRT.

Let the set warm up for at least half an hour. Display a good quality

signal. Turn the user color control all the way down and the brightness

and contrast controls all the way up. This will be the worst case. Adjust

the focus control for best overall sharpness - you may not be able to get it

perfect everywhere - center as well as corners. If best focus is at one

end of the focus pot's range and still not good enough, there may be a

problem in the focus divider, focus pot, or some related component.

  21.4) Adjustment of the internal SCREEN and color controls

The screen should be adjusted with a white pattern (snow from the tuner

should do or turn the user COLOR control all the way down to get a

black and white picture). Put the set in Service mode (horizontal line)

if it has such a switch in the back or inside. If not, just use

the raster in a darkened room. Adjust screen for a dim white

line (raster). If the line is not white at its dimmest point, you will

need to adjust the drive and cutoff controls for R, G, & B.

Alternatively, you can use the following procedure:

Turn R, G, and B screen (or background) controls down. Now turn color

control fully counterclockwise -- off. Now turn up red screen until the

screen just shows a red hue. Now turn red gun down until red tint just goes

away. Now do the same with the green and blue screen controls. Now adjust the

two DRIVE controls for the best black and white picture. That`s all there is

to it. I don`t like to work with just a thin "SETUP" line. Cartoons seem to

be the best thing to have on while doing the above procedure. You can

also use just plain snow (no program) if you prefer. If you can obtain a

good b@w pic. when you`re done, the tube is good and the set if most

likely functioning properly. Be patient and go slow while watching the

large mirror that you are using during this procedure. (LEE)

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