Hello all, I'm having troubles with NEO TV-2188TXS (chassis KP2107AST) which my friend brought to me to check is it worth repairing. I'm expirienced with electronics but not too expirienced with tv's. Picture goes on and off, sometimes faster, sometimes slower with retrace lines when it is on. Upon opening I noticed corona inside crt neck about 5 cm's bellow crt socket which goes on about same time as heaters get hot and flickers at about same freq as picture goes on/off. When picture is on, focus and brightness apears ok.
Is it crt that is gone bad or is it a breakdown inside fbt's focus network?

yes, I forgot to mention that whole board gets charged and after turn off I have to wait for a while for it to discharge, I even got zapped through a power chord!

You are losing G2 or focus volts the corona as you call it is the tube conducting so G1 is OK electrons pass this and head on and hit a barrier, so the congregate in a cloud. Is it the tube, check voltages, find out where the voltage is failing. Your other issues are not issues, if you pull the mains plug out of any TV too soon the chassis will charge and you will be zapped.

corona inside crt means bad vacuum (bad tube).
It causes too high beam current (EHT supply overloaded) and the
TV shuts down.

Thanks for reply's guys.
I hope you guys don't mind all those newbie questions. It helps alot, expecially what rrobor said, it changed my whole point of view.
At the moment I can't tell you more about volts because I'm not at home for a few days.
What I remember is that 'corona' forms on one side of the tube right undeneath the glass in area around (not inside) big (last one I think) focus anode. I can't say does it go towards g2 and g1 because that area is covered but I noticed that it formed a darker area on the glass itself in form of one wire that connects two sides of focus anode.

One more thing again, as my friend explained to me set sometimes works fine for some time but usually it works a few minutes and then it turns off, as bejkolam mentioned.

bejkolam is telling you about a gassy tube, that will spark and arc. if you have a quiet tube with a sort of green haze inside that is what I was describing. This is not a common fault, a gassy tube is but with a gassy tube you should be getting sparks across the spark gaps on the tube socket and all sorts and its violent, you dont peer into the neck to see whats going on.

Yes it is quiet actually, there are some snaps but they are not loud and when one is heard haze dissapears. I have some spare time so I made a picture as I remember it.

I will dare to ask some more newbie questions, hope you don't mind. More o/t.

1. What happens to the beam and picture if focus voltage is totaly missing, or is very low? Is beam still getting to the screen or not at all?

2. What happens if focus voltage is excessivly high?

3. What happens when G2 filter cap gets open and not filtering? When it gets leaky that is obvious, low or none G2. But what interests me is what happens to the beam without g2 filtering.

Thanks in advance, I hope I'm not bugging any of you too much.

Heck that thing ain't gonna work, the glass in broken ! I definitely know the picture tube is bad now. I didn't know it was broke.

It's not broke, it's not the actual picture of the tube.

Ok, problem appears to be solved or atleast now I know where problem is or was. What rrobor said about loosing g2 or focus changed my whole perspective to this problem and focused me on how tube actually works and how it is related to the problem. I came home this morning and turned on tv to see what actually happens and I saw that when picture dissapears it doesn't dissapear totaly, there was a black raster but no picture. If there were no G2 voltage then there should be no raster at all so I thought that there must be a problem with focus voltage. What also turned me to think that there is a focus problem is a haze that rrobor mentioned and how electrons actually hit a barier, haze was actually apearing in area of focus grid. I don't have a high voltage voltmeter or high voltage probe to measure G3 so firstly I started to look for any sign of wiring problem. Wire looked ok so I started to look at focus crt socket with its housing, focus wire box (I don't know how it is actually called)on crt socket appeared ok but I've seen that it could be opened so i desoldered focus wire and opened it. One part of a sparkgap from inside fell out, I don't know if it was in place or not but I putted it in place and closed the box, resoldered the wire and putted board back to crt. Turned on tv and first what I noticed was that there is no haze in the crt anymore. Picture was ok also. Voila! It works for an hour or so already with no problems. So focus socket box was leaky for shure, I just don't know was it because of a sparkgap part or it was just leaky for some reason. I will se how it performs now and if there is need for replacement, I will replace it.

Thanks everyone for help, especially rrobor who pointed me in a right direction.