TV HORIZONTAL SECTION PROBLEMS AND SOLUTIONS:

Horizontal deflection shutting down:

Confirm that the horizontal deflection is shutting down (along with thehigh voltage since it is derived from horizontal deflection: listenfor the high pitched deflection whine, test for static on the screen,see if the CRT filaments are lit, turn up the brightness and/or screencontrol to see if you can get a raster) and then why:

1) Power is failing to the horizontal output transistor - this could be due to a low voltage power supply problem, bad connection, etc.

2) Base drive to the horizontal output transistor is failing - could be a fault in the horizontal oscillator or bad connection.

3) Problem with the fly back transformer or its secondary loads (fly back may provide other power voltages).

4). X-ray protection is activating - either due to excess HV or due to a fault in the X-ray protection circuitry. If the problem comes and goes erratically it sounds like a bad connection, especially if whacking has an effect. If it comes and goes periodically, then a component could be heating up and failing, then cooling, etc.



Horizontal lock lost:

A TV which loses horizontal lock when changing channels, momentarilylosing the signal, or switching inputs may have a horizontal oscillatorthat is way out of adjustment or has drifted in frequency due to agingcomponents. Note that the characteristics of this are distinctly different thanfor total loss of sync. In the latter case, the picture will drift sideway sand/or up and down while with an off frequency oscillator, the torn up picture will try at least to remain stationary. This could be a capacitor or other similar part. Or, the oscillatorfrequency may just need to be tweaked (particularly with older sets).There may be an internal horizontal frequency adjustment - either a potor a coil - which may need a slight tweak. If a coil, use a plasticalignment tool, not metal to avoid cracking the fragile core. A schematic will be useful to locate the adjustment if any or to identify possible defective parts. Try a large public library for the Sams' Photofact for this set.



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. Thisis used during setup to set the color background levels. (On some sets, thisis located on the CRT neck board and may be a jumper plug or other means ofselecting service mode - not an actual switch).When moved to the 'service' position, it kills vertical deflection and vide 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 orbad connections to the yoke.

REFERENCE
http://www.stedmundsbury.gov.uk/sebc/play/tvprobs.cfm
http://www.epanorama.net/links/repair.html#tv