CRT Focus?

[2cvbloke]

Our TV's bugging me, over the past year, the focus seems to have gone on the screen, with the edges looking blurry (easily seen with on screen graphics & logos), and it got me wondering (uh-oh!!! Bad thing!!! )...

On my little toshiba portable, it has knobs on the flyback transformer, and I'm sure one was for focus, so the wondering is, would a fairly modern (for 6 years ago!!) Sony TV have something similar to refocus the image, or is it getting near to needing to be replaced?

Another thing bugging me about it is the colour hue seems to shift a lot, not like a psychedelic random colouring, but the colour just seems to shift slightly depending on the picture, so some images look quite yellowed, and others normal...

And yes, I know the dangers of flyback transformers, having seen them on YouTube made into things like Jacobs ladders and suchlike, they are something I wouldn't want to have discharge through me!!!

 

[Channel Hopper]

Sony Trinitrons used to have one knob similar to the flyback adjustment, well away from the circuitry on the EHT line, to bring everything back into focus. It was usually stuck on upper right fromt he back, not far from the back of the tube itself.

Now I wonder if Plasmas or LCD tv's are guaranteed to remain pin sharp from the factory as they cannot be adjusted from the design

 

[BombedOne]

Generally, sony tv's from year 2002 (maybe later, don't remember exactly, have to check service manuals) have special interface, to which, in the service, they connect special set of controls, and using them for adjustment. Hovever, check your FBT (flyback transformer), mostly it has 2 knobs, one adjusts overal "brightness", while 2nd adjusts "focus" (in reality they both just change voltage on apropriate electrodes of the tube), but, as I can guess from your post, what you're facing is general loss of emission by cathode, so fiddling with FBT won't help at all.

Lost emission is not uncommon even to modern CRT tv/monitors. For example I have an LG 17' Monitor, manufactured in Q3'2006. For today, it's emission current is about 20% of original.

 

[2cvbloke]

Sony Trinitrons used to have one knob similar to the flyback adjustment, well away from the circuitry on the EHT line, to bring everything back into focus. It was usually stuck on upper right fromt he back, not far from the back of the tube itself.

Now I wonder if Plasmas or LCD tv's are guaranteed to remain pin sharp from the factory as they cannot be adjusted from the design

Hmm, I'll have a look into that, once the mother's out of the house (she doesn't like me fiddling with her telly, took me ages to convince her to let me fiddle with the aerial (in the loft) to get the freeview signal working ages ago!!!)...

Speaking of which, does the same apply to their Trinitron Computer monitors? I'm just sat next to a Dell branded one at the moment (working on my IBM server, thinking of what to do with it!!!) and it looks a bit out of focus, might fiddle with that one too...

 

[2cvbloke]

Generally, sony tv's from year 2002 (maybe later, don't remember exactly, have to check service manuals) have special interface, to which, in the service, they connect special set of controls, and using them for adjustment. Hovever, check your FBT (flyback transformer), mostly it has 2 knobs, one adjusts overal "brightness", while 2nd adjusts "focus" (in reality they both just change voltage on apropriate electrodes of the tube), but, as I can guess from your post, what you're facing is general loss of emission by cathode, so fiddling with FBT won't help at all.

Lost emission is not uncommon even to modern CRT tv/monitors. For example I have an LG 17' Monitor, manufactured in Q3'2006. For today, it's emission current is about 20% of original.

Hmm, that could be a bit of a bummer if the special interface is needed, but still, where there's a will, there's a way...