ITT-KB CVC5 26" help

[stubbyeddy]

I have been looking for a good sized early colour tv to use as my main set for a while and got hold of this ITT-KB. I got it off the chap that rented it out to the same family for the past 40 years right up until 2011.
Any how after a bit of tweaking its working perfectly with a stunning picture apart from as I hope will be clear from the photos is that in the bottom left of the screen the picture bends up slightly and with it the convergence goes out a fraction, now my question is, is this considered acceptable or can i make it better? and if i can make it better what do i do? Im hoping maybe something was just moved slightly when it was transported that i can just move back, but i dont want to start fiddling with the wrong part and make it worse!

I have been in the back of this as i had to solder up a repair and check some fuses as it was bumped about in transit, but im not sure what all the adjustments do on an early colour set so dont want to mess about with them at make anything worse!! any help you guys can give me would be very much appreciated. Im a bit thick to try and keep it simple Eddy

[bobbyball]

That's a great picture already but there is a bit of raster distortion as you say.

Have you tried adjusting the "pincushion" correction controls? These are designed to "straighten out" the top and bottom of the picture and it is best to use a test card or pattern generator for this. You can get the test card on a Freeview box - see the "sticky" relating to this on this Forum.

Can't remember exactly what the componenet references are on this chassis but there will definitely be a coil that has an adjustment and possibly a variable resistor ("pot"). The circuit etc can be purchased on this Forum (£1.99) if you don't have it.

The 26" version of the CVC5 is quite rare now, had my example stolen, incredibly!

Best Regards

Robert

[stubbyeddy]

Hi Robert,

I have seen the pincushion controls but haven't tried that yet, at the moment i dont have a modulator to plug my dvd player into to get a test card or cross hatch ect up on screen, so i wont touch that until i can get that up. Also its hard to really see from the photos i have put up, mainly as its not on a test card! but the rest of the picture is fine but for the very top and bottom left hand corners. On the right hand side of the screen its all perfect.

[ekcopyephilips]

Personally i would leave it as it is. Acceptance levels in the 70's on pic quality were probably a lot more lax than you would expect, i.e. if its not noticeable on a normal picture from a normal viewing distance then its passable. I tried to do some adjustments on a G8 convergence and managed to damage a coil on the line scan panel in the process. Nice crisp looking picture on that set too.

[malvision]

The picture on the tv looks great i would leave it as it is.What you must remember is because we are all used to HD,flat screen tvs etc.Older sets look a lot worse than they really are in terms of picture quality

[bobbyball]

Hello again, well I would agree that the picture is quite superb but having a few of these sets myself (NOT the 26" model since the "burglary" where it was stored sadly...) that it would certainly be worth at least trying the effects of the pincushion controls, could even be a component on it's way out... The design of these sets originates from Germany (their version had a valve eht rectifier but wasn't much different otherwise) and our Continental cousins didn't do things "down to a price" like the Brits seem to need to do so I'm sure it can be "got better"!!

I'll study the manual (if I can find it!) and see which and where the adjustments are, off to work now...

Be worth getting a Freeview box for it, these often have modulators.

Cheers again

Robert

[Nicklyons2]

I echo the thoughts of some above in that if it looks OK on a standard picture I might be tempted to leave it. But if you fancy having a go just don't force any adjustments that have stuck with heat - you'll move them eventually - to a worse position, then they'll break and you'll end up with a worse result. Some of the wirewounds in the convergence circuitry sometimes sort of welded the slider to the track over long periods so if you disturbed them the track broke.

The picture looks a little tilted down on the RHS from the photo; if it is, get the picture levelled up before you start adjusting pincushion etc. These were, in my view, very good sets and if you get one with an Japanese tube they just seem to go on and on.

Just out of curiosity; was this the one recently on a 'well known auction website'?

[HamishBoxer]

We are i believe allowed to say Ebay but not promote other members stuff on there.

[Welsh Anorak]

Hi there
Personally I think the picture can be made better - that's quite a bit out. Of course, perfect geometry is the preserve of the flat panels, but still a delta-gun can give very good results.
Now where to start? I suspect the transductor itself on this is giving the trouble - there's not much else in the circuit, though it's a good idea to check the other parts in the area first as they are easier to obtain.
Let's have a look - check R364h and R435h (22 and 47 ohm respectively) and of course the 150 ohm wirewound pot R362h - see what effect it has. Also check the adjustment coil L125h doesn't look burnt, and be very careful if you feel you need to adjust it.
It looks a great set and ready for the next 40 years. In an idle moment it might be worth considering exactly how much the set has generated in revenue for the lucky previous owner!
I agree it was based on a German design (the FT100, I think) but that is really quite different when you look at the circuitry. I think that, along with the Philips K70 and B&O 3400 was one of the last sets that used a G501 EHT rectifier (no shunt stabiliser) - we were well used to triplers here by then.
Glyn

[bobbyball]

Wasn't the FT100 one of "our" sets??

I know the FT200 was a set imported from Germany but it is solid state unlike the CVC5.

Going back to the raster distortion yes I agree with Glyn and really think it could be "got better". Beat me to it looking for the service data.

I'm still jealous at seeing a 26" CVC5 working so well!

Robert

[stubbyeddy]

Thanks for your advice everyone!, I didnt get the set off ebay but it was on there at some point I believe. I should have asked about how much it was rented for ect but as it came to me via a friend i didnt have chance to ask a lot about it sadly, I didnt think to much about it being quite scarce, I just liked the look and the picture seamed very good and perfectly watchable for our main set. I think im going to leave the picture adjustment up to someone thats had a bit more to do with this type of set, its perfectly watchable as it is so to avoid messing it up im going to get some capable hands out it hopefully!! (its a beast to move!) it would seam a shame for it to last this long and me end up damaging it only having it 5 minutes!!

[n_r_muir]

It really is best to leave well alone, the CVC5 is full of convergence controls, linearity coils pin cushion correction controls etc and from memory they all interact like crazy and you can easily end up screwing up a perfectly acceptable picture.

Ross

[stubbyeddy]

Hi Ross, im going to take the advice to leave it as is for now and I will get someone with the right gear and experience take a look at it at some point.

Just incase anyone was interested seeing it up and running I put a video up on youtube http://www.youtube.com/watch?v=i8-pw3Xj46I I noticed there wasn't much in the way of all valve or hybrid UK colour sets on there so put one up

Eddy

[pichacker]

And ITT have um tint control. As the advert used to say.


What a stunning picture. Nice find.

[Studio263]

Originally Posted by Welsh Anorak

Of course, perfect geometry is the preserve of the flat panels, but still a delta-gun can give very good results.

And old broadcast monitors Glyn! Sony PVM-1444QM - spot on.

The CVC5 > 9 was a sturdy beast but they were a bit "blue collar", not really a luxury set (even the ones with Aristocrat written on the front). Because of this you can't expect flawless convergence and geometry (you needed a B&O 3400 and plenty of patience for that!) but it should be possible to make it pretty reasonable. The oldest ITT set that I encountered that you could really set up nicely was the CVC30, shame about the comedy LOPTs they had in them. This was resolved with the CVC40, an excellent chassis but they only did little'uns (16").

Remember that when these sets were new the broadcasters used to do the decent thing and not put anything too close to the corners of the screen that would highlight convergence errors or "breathing" effects caused by imperfect EHT regulation. Sadly they don't do this any more so the shortcommings of some older sets are revealed in a way that they never used to be, however you could see this as all part of the fun.

[AlanC]

Might sound a daft question, but it isn't sat next to a hi-fi speaker or anything else with a big magnet in, is it?

[Welsh Anorak]

Hi there
Wise move to leave well alone, but keep an eye open for a transductor - they are the same on most British sets of the period (eg G8, Decca 30, Pye 693 series and so on) so you might well find one. The worst that can happen is that it fail completely, but can be safely left out of circuit, but obviously with some bowing.
There weren't that many 26" CVC5s (or not that I've seen) but they certainly gave a good picture - in my opinion far better than the later revamped decoder in the CVC8/9. Just be gentle with the channel buttons.
Now Tim - I'm sure there was a 20" CVC40 - or was that a CVC45? Diode-split LOPT and a farewell to British made ITTs.
Glyn

[bobbyball]

I certainly have had and indeed do still have a number of 20" and 22" CVC5-9 sets.

They "are" capable of an excellent picture and with good raster geometry.

Never got the chance to see my 26" model in action before it got "nicked" but I would imagine a pretty good picture can be got on that size tube as well.

Transductors do come up every now and then on eBay and the like and if they fail it's usually obvious (smoke/burned appearance) and can cause raster distortion.

However this is quite an "involved" fault (if there is one) and should be left to somebody with sufficient experience if you don't feel confident.

[Hybrid tellies]

The company I worked for had a lot of CVC 5's out on rental from 20" to the 26" models. They were very reliable and gave the best pictures. They were easy to repair and set up to give good convergence and geometry. They were much liked by the customers and engineers. I do not remember ever having to change a tube on one either. The picture on yours looks good and only a set up with a pattern generator and/or test card DVD would be required to bring a small amount of improvement. You have already done a good job.

[stubbyeddy]

Originally Posted by AlanC

Might sound a daft question, but it isn't sat next to a hi-fi speaker or anything else with a big magnet in, is it?

Yes they are a pair of Dynatron loud speakers, I have moved them right out of the way and it doesn't improve anything but thanks for pointing out as I nearly over looked that!!

I am going to be careful with the channel buttons in fact all the knobs, not that are used much just changing from sky or freeview box to dvd or video.

The set has been realy well looked after, aparently just sat on cupboard in the same room in the same house for 41 years and just dusted lightly once a week, all i had to do is give it a wipe over with cloth and polish it up.

If anyone can give me anymore info on the set like copies of old adverts, user manual ect.. id love to read them.

thanks again everyone I will progress info on the set once I have had it looked at with the right gear ect.

Eddy