DISASSEMBLY AND REPAIR: IVT L-2021

IVT L-2021 from 1996\1998

ITV, this is the brand of this CRT televison set. Could this be an Apple Product? A big "NO", by far! This is one of those rebranded televisions, which is obviously a cheap quality tv. Even so it has relatively nice and big (?) screen but it was completly dead. When plugged in you could only hear a short beeping coming from the switching power supply. Something was quite obviously shorted on the secondary side of the circuitry of the tv. Time to take a look.

Needless to say that there was a dusty mess inside as always with CRT sets. Ok it was not that bad but a cleaning job was on its way..

I removed the whole chassis from the cabinet leaving behind only the speakers and the CRT itself.

Having the chassis freely standing on my bench, it was time to clean the dust and to inspect it for possible visual problems.

A burned resistor, although this wasn't the only one in this condition, they were still within value, but replacement was required and on its way.

A cracked polyester cap. Actually one of the leads separated completely right after i bent the capacitor just a tiny bit towards the flyback transfomer. This one had to go as well.

A really bad looking electrolytic. This tells me that this capacitor has been heating for a while. The plastic shell shrunk and broke due to the heat coming from the heatsink nearby. Actually nearly all high voltage or high capacity caps were either buldging\leaking or had its plastic cover shrinking due to heating.




Signs of possible moisture on the PCB since this tv set was living in a kitchen all its life.

 And this is over the high voltage area. Actually this was almost over the whole mainboard and also on the CRT neck board as well. It had to be clean.

Bad solder joints. No wonder the owner complained that he could barely hear the audio from the tv. This is the amplifier IC chip which had nearly 50% of its solder joints broken. Actually this tv ended up being target of some physical violence in order to "play right" :)
No wonder there were a whole bunch of broken solder joints in other areas on the pcb as well. All that was repaired too.




None of this helped the tv work again, so i started checking the usual suspects. Turns out that a NPN fast switching transistor used for the horizontal deflection was shorted on two pins. In the picture on the left is the defective one, and on the right is the replacement. Time to apply the new one and test the tv again.

And the tv lives again hurray! But wait, what the...?
There are horizontal lines on top of the image, something was not right still.

So i decided to replace all the electrolytic capacitors inside this tv since nearly all of them showed signs of deteoration. If this was not the case i would try to replace the caps in the vertical deflection area only.
Here kitty kitty.




Lets have some fun..or not.




Look at that leak! A whole lot of them were like this. Nasty stuff.




Electrolyte stain on the component side of the pcb. It had to be clean before applying the new capacitor.




After cleaning result. What you may think that its still dirtyness is actually a small corrosion on the pcb caused by acidity.

Job done, all FORTY FIVE electrolytics were replaced. As you can see i removed the flyback transformer to avoid damaging it while replacing the capacitors since there was a lot of board flip-overs during the process!

Polyester cap also replaced!

New resistor in place.

Another new resistor replaced (red one). In fact all burned resistors were replaced.

And voilá, all this work was for nothing as the problem was still there! Well, it wasn't an unworthy work at all as i would have done either way.

At this point the problem was quite obvious, the vertical deflection chip must be defective. I decided to consult the staff at the ukvintage radio forum and after all the work i already had done the general opinion was quite unanimous. The vertical deflection chip had to be bad. Why the vertical chip? Well these lines you're seeing are a small remnant of probably less than an inch of the top of the image being folded over the screen area. Sometimes you could see the lines and a smal activity in them, and some other times you could see this shrink effect above.

Time to replace the defective TDA3653C vertical deflection chip and see how it goes. Bad chip on the left and new one on the right.

Hm. Seems that something went wrong. How annoying...Well after checking and rechecking my solder joints i could only assume i have got a defective chip. How often does this happen? 1/100 so does the store clerk say. I had to pay to get another one by the way.

And finally i got the image right with a second new vertical deflection chip.

Now this is definately more like it! The image is perfect now!

But i still had problems with the audio. This is a stereo TV and i could only get audio on one of the channels, and everytime i cranked up the volume the image would get distorted and audio would get all corrupted.

Even though it was quite evident that it should be the audio amplifier chip TDA7057AQ that was faulty, i decided to test each channel separately. The chip had to be changed and afterwards the audio was perfect and no problems with volume raising anymore!

But i wasn't still free of troubles with this TV. I tried the scart input and for some reason the image was all muddy. Hooking a computer to the tv generating a tv test pattern image made it clear that something was wrong.

After further investigation on the schematics i was able to trace down the video input circuit. It went to the video processor chip and to the tv functions\teletext chip. I couldn't sort what was exactly faulty but i could only assume that it was some problem with the tv functions chip as when i disconnected the video input from it the image went completly clear and perfectly sharpen. I acomplished this by killing the shunt shown in the center of the image above. It wasn't worthy to replace this chip as the rest of it was perfectly operational and it would be really expensive to do it. The only lost functionality was the teletext through videoinput.



After doing so much, i decided i was going to do a final treat to this tv. I decided to wash the case. For that i removed the CRT, the speakers and a few metal parts.

The cat certainly enjoyed using it as it's new home! Sorry, no can do kitten, that isn't yours!




With everything done, clean and fixed it was time to do some cable managment and assemble the TV once and for all.
You might be thinking, was it worthy? Well money wise it was, it would cost you a whole fortune if you'd get it to a tech store to get it fixed, but if you do it yourself it is pretty much worthy. I didnt waste more than €30 on this, and trust me, i replaced a incredible number of parts to get it going and lasting.
For the trouble it gave me...well if i didn't take this so personal (like a personal exercise) it wouldn't be worthy at all, this took me way too much time and effort. Well, it works now and i hope the owner feels happy with it again, even though it's a completly outdated cheap crt TV :)
I hope you enjoyed it also!

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!