In one 21"color CRT tv vertical linearity is lost suddenly and picture is streched from upper side and compressed from bottom side (no rolling and we can see the movie but streched. In vertical section preset could not change the error.Vertical IC 7830. I replaced 1000Uf and 220 UF capacitors with new one but didnt solve.(i donthave oscilloscope )what can i do now.Thanks in advance
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Re: CRT TV vert section
Vertical linearity is more of a DCV bias issue rather than feedback or AC coupling. Hence it would be more apt to suspect resistors rather than capacitors. Of course, it is also possible that the large IC that drives the Vertical output maybe at fault (least likely) but often would have trimpots for adjustment. Most current designs do away with trimpots and rely on self correcting (feedback loop) which is simply a resistor in the 100k range. In certain instances, it could be a thermistor or resistor or diode limiter attached to the yoke itself.
Best would be to use a service manual or at the very least a schematic diagram with voltage readings and compare actual on PCB against schematic.
If you could post back the make & model or preferably the chassis number of the TV, might be able to comment back known common vertical issues.
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.
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Check and replace all the electrolytic capacitors at its vertical scan output section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" or "Magazine" will make surf easy. Pull up older posts. Surf the site with patience. Do a search by type in the brand name of your device at its search box. http://electronicshelponline.blogspot.com/
Check and replace all the electrolytic capacitors at the vertical output section circuit. There will be 5 or 6 of them. Replace all at same time. If it do not help you, you have to enter its service mode option to adjust the vertical leanearity of the picture. It is a skilled job. The service mode window is entirely different to that of Menu window. You must have through knowledge in electronics to follow. Improper adjustment to this window might make TV irrepairable.
Possible failure of the VERTICAL SECTION of the deflection circuit. It is possible that the areas related to the vertical circuit is checked , check for weak capacitors near the output vertical drive. Also a faulty vertical coil- deflection coil- can result in half picture. A vertical signal test can confirm.
If you have a hot air gun like used for dry the hair, apply hot air on the vertical section, if the trouble is solved sure is an electrolitic capacitor, find it hoting one by one with de solder, if not, may be is the defletion yoke, the impedance is not less then 7 ohms.Another probe for the yoke: disconect the vertical wires and supply 12 VAC with a transformer to vertical coil and turn on the tv and watch, if the vertical size is ok, the yoke is ok.
your problem is from east west ckt . there is a transformer used in this ckt which Dry solder and works inttermittent ( shrinks & expend ) . resolder this transformer . iam working with philips ......... enjoy
I noticed a bright horizonal line about 1/4 in.wide centered in the middle running from side to side. Audio is fine. This just all of a sudden happened it was not gradual.
it is due to vertical section failure.
please minimise bright to protect crt.
1 check supply to vertical section.
2 check for ic failure in vertical section
3 check vertical output section parts.
Is it fixable or dumpable?? Please HELP!!!!
yes it is fixable
it is common problem not major one.