Is it impossible replace bi-polar capacitor with film capacitor?

[jzx]

If the original fail were the outlines around the letters



the fail is not in the deflection circuit, can be something as simple as a bad video lead, as another member has said you.

Now you have 2 fails in your tv.
 
First you have to restore what you have done changing capacitors. The audio is not very good, sometimes  interferences from the magnetic field of yoke in the phone can be heard (I think they are not real sounds), but it sound like sparks and some hiss (the hiss is real o interference?)

If you have not deformations of picture, jumps, flashes,  too wide or narrow picture or other geometry defects, probably the fbt is not broken, but having sparks is not good.

Have you made the test in darkness?

In the cpt board there are sparkgaps, if there is some dirt or particle (some have the gap open to air) that dirt can cause discharges. I dont know what type of spargaps use your tv, but some are like a capacitor with a slot. Look at them in darkness.

Have you checked if the HV lead is lose, if it is removable?

[jzx]

It seems tha the sparkgaps are integrated into the crt socket, not open, so probably they ar not the problem. You have also CK901, that can be an open sparkgap and SG900 that seems a neon bulb.

[bshi02]

Thank you very much for reply.
I purchased 400v 2.2uf capacitor(samyoung SHL which has higher specification than SMS capacitor) and replaced C406 with it But It won't got rid of weird loud noise from Flyback transformer.

So I tested it in darkness and in bright in turn,I finally found that there have been leakage in the thickest wire of Flyback transformer.
(You can confirm from below video that there is a dim light in darkness which is locate in the position of the thickest wire at the bottom)

https://www.dropbox.com/scl/fi/8kc0cpz09gz97edc0bmu9/20240727_234016.mp4?rlkey=y68x2jlx8saevlujbzwg6zmg1&st=zciveo6o&dl=0

and I also recorded it at close range,You can obviously confirm that there is tiny arcing from the thickest wire at 0:25
https://www.dropbox.com/scl/fi/yqggr0943as6dm82jhrnu/20240728_074059.mp4?rlkey=2cvx6vqolix5tdgykzuirm3sa&st=vxjio3fc&dl=0

It is very difficult to purchase LG 154-179M FBT at the present and Its cost is insanely expensive in ebay ,So I looked for epoxy or silicone to cover this arcing position,But I think that even if I apply epoxy or silicone on the arcing position, It would be just temporary expedient and will eventually arc again...

https://jestineyong.com/arcing-in-flyback-transformer/

[T3sl4co1l]

Oh incidentally, out of curiosity I measured an old (possibly 1985 date code) Nichicon HF nonpolar.  10uF, 25V, a whopping 18 x 37 (D x H) mm.  Value was within 10%, and ESR was a whopping (drumroll).... 50mΩ.

They can certainly make them smaller than this ancient one, but the ESR is impressive compared to standard offerings.

Tim

[jzx]

Clean well the area of arcing, and see with a magnifier if there are crackings in the wire.
Search the datasheet of fbt to known if the wire is replaceable. As the crack must be near the fbt, if the wire is replaceable, and can be removed you could cut a bit of wire to avoid the damaged part and reinstall the wire, normally is long enough. But you must first be sure that the HV wire is removable, and how. In some fbt it is removeable, in others not.
And you must consider how the wire has been damaged. Have you forced? Is too old and the plastic is degraded?

In the past there was a product specially designed to cover cracks in fbts (when all tvs have one), but I don't remember the name, and surely now is not manufactured.

I don't think that is related with the capacitors, unless you have bent too much or pinched the wire while changing capacitors.

Not very related, but if you change some capacitors in the H deflection circuit, you can raise too much the HV, and increase the X ray emission. I think that in this case the picture is abnormal, too much narrow or wide, not your case, but it is another reason to not play with this circuit.

[bshi02]

Thank very much for reply.
In fact,I have desoldered  top-cap which clips to the CRT cut off the end of the thickest wire and slip 2 layers of adhesive-lined heatshrink over the wire,(one layer is adhesive heatshrink and the other is not adhesive heatshrink),shrink it with lighter then resoldered top-cap like below pictures.

https://www.dropbox.com/scl/fi/oy1g4mpw6nvwnvufoekcq/IMG_20240729_193343.jpg?rlkey=kg0akxy4tbm7200u8ehkwx2u8&st=pjsj57g9&dl=0

https://www.dropbox.com/scl/fi/g3avecn28cwa245bim3z2/IMG_20240730_144220.jpg?rlkey=xb8lexka7wqtham516jwshbhn&st=nifgqu32&dl=0
and I also use gluegun in order to melt and apply sticks of adhesive to the area of arcing.
Although It was impossible to make a completely zero leakage from the thickest wire of FBT like below video, when I recorded it by bring android phone closer to the area of arcing,But It is not as loud as before,It is rather quite little noise,and there is no dim light in darkness at all.

https://www.dropbox.com/scl/fi/4eftus1ke40qpr423evfx/20240803_145905.mp4?rlkey=46r0ytv1uuv5cqkpff3jixhrr&st=pe1qjium&dl=0
I tested this CRT TV over 2 hours,But There was no abnormality in displaying.
As currently It is impossible to purchase 154-179m or HR 8251 FBT from my place, So I think that very small leakage from the thickest wire of FBT would not breaking out fire or explosion for a fairly long time

[jzx]

The corona discharge or sparks make ozone, not good for health, and over time degrades the plastics, specially in the holes/pores where the discharge occurs.