DISASSEMBLY and REPAIR: Sony Triniton CRT TV model KV-14M1E

Sony Triniton CRT TV model KV-14M1E from 1999/2000

Now that LCD TVs are the kings (not for long) and with digital TV signal replacing the older analogue one, CRT tvs are pretty much depreciated and seem to be pretty much useless. Well not really and not by me certainly.
I was given two TVs, being one of them the well known Sony Triniton CRT TV model KV-14M1E that was suffering quite badly from convergence problems. I didn't even knew the name of the fault until i really searched about it as i never had to dwelt with it. I'm still in the process of learning about CRTs and i must admit this was interesting to fix but also quite a pain.

And this is how the image quality looked like. You can notice that it is quite terrible. It isn't out of focus. The problem is "convergence purity". As you might know, every color can be composed from three basic colors. RED, GREEN and BLUE. This is how CRTs and LCDs make colored images. CRTs use 3 electron guns, one for each color. The electrons from each gun must hit perfectly on the same spot on the phosphor surface inside the CRT.

So basically there is a misalignment of the three guns and they are not overlaying the electrons correctly on the screen, creating this fuzzy image, Notice that even the subtitles are hard to read.

  

 So i opened the TV. There was dusty mess inside as expected, especially around the high-voltage area of the TVs motherboard.

 A view of the other side. The latest CRT tvs were quite empty when compared to older tvs that were usually full of daughterboards!

 

 Here is a view of the back.

 Here is a before-after cleaning picture. Thank you air compressor, you have served your purpose.

 Ok. Now lets analize the problem. At the beginning i was a bit lost where to start. I knew i should start searching for some adjustment trimmers before assuming there was some electronic malfunction. But the only two obvious adjustments inside the TV were "FOCUS" on RV704 and "SCRN" on RV703, and none of them sounded right. I went ahead and talked to a few guys on the UK Vintage Radio Forum (thank you guys, you were awesome) and there i found some pretty knowledgeable people about this particular TV chassis. Turns out i should search for some adjustment saying H-STAT either on the crt's pcb or on the yoke itself. Unfourtanely there was nothing like that on these newer TV sets which led me to a last resort solution.

I needed to mess around a bit with something here on the back of the CRT.

This was the thing to mess with. You only want to mess with these as a last resort as it can get worse if you're not patient enough. These are convergence purity magnets.

 

These are composed by magnet rings. You should rotate each one at a time really slow so that you notice what they are doing until you get a desirable result. There can be a few of these and it can be tricky to get the perfect combination. You can either take 5 minutes to half-hour depending of how perfectionist you are.

 Before starting you should have a image pattern generator. I didn't have one so i used a computer with TV OUT. Unfourtanely my modern day computer didn't like the Sony TV and the only computer i had left with TV OUT was an old Pentium 1 120mhz. Lucky me heh?

This is the best image to use when aligning a crt convergence.

This is how it looked. Don't cross your eyes, there is nothing wrong with them. This TV had a seriously bad convergence purity problem.

Here is a closer look at it. You can clearly see that the three basic colors are completly misaligned. Inside the squares you should have one dot only instead of 3 separated colored dots (three basic colors, RED, GREEN and BLUE).

 Having a mirror facing the TV while doing this is a must.

 

Since this was a really small TV i also used a webcam poiting at one of the dots. But this isn't quite a good help because you wont get a even pattern on the whole screen.

And this is the result after a while. Some CRTs can be more picky than others and take you more or less time.

I did a new marking on the convergence purity magnets which is highlighted by the red rectangle. Notice the older white marking above completly jagged. That's how much i had to move the ring magnets.

Probably you won't get a 100%  RGB match (RED, GREEN BLUE) across the whole screen. The corners will probably look like this or worse. This can be fixed by using a strip with permalloy. These are called, you guessed, permalloy strips.

This TV happen to already have one and since i already messed around with the magnet rings, i had to realign the permalloy strip so that the corner looked better.

 The permalloy strip removed from the CRT.

 The permalloy strip realocated. This isn't the best way of doing it. I used electrical isolation tape to hold the permalloy strip in place, but doubled sided tape or hot-glue should work better in a long term.

This is the final result. Notice that the subtitles and even the channel's logo are much more clearer now!