Settings not affecting RGB signal on Sony Trinitron

[Professor Jones]

Hi,

I just got a new CRT, model KV-21C5B. When I input an RGB signal the sharpness and colour settings don't affect it at all. Luminosity and Contrast do affect the signal on the other hand. What could be causing this ? I really hope there is a solution because I will never be able to get a nice image without having access to these settings

[buttersoft]

Assuming for the moment that consumer trinitrons work to the same principles as PVMs... Aperture (sharpness?) and Chroma (the single "colour" setting, not three settings for individual colours) do not affect an RGB signal, and will only work with NTC/Svideo/Component signals.

Hi,

I just got a new CRT, model KV-21C5B. When I input an RGB signal the sharpness and colour settings don't affect it at all. Luminosity and Contrast do affect the signal on the other hand. What could be causing this ? I really hope there is a solution because I will never be able to get a nice image without having access to these settings

[adder]

it can be quite hit and miss with different tv's unfortunately on whether you are allowed to adjust the colour when in RGB mode - i have found most often that this is not permitted, however some tv's such as some JVC tv's which i own do allow it, via the service menu)

regarding sharpness, again this most often wont work in RGB mode, however you could try what i do, which is, try adjusting the 'focus' knob found on the flyback transformer (if you are trying to get a sharper as possible image, just adjust the knob until it is set at the best possible ('center focus'), however if you prefer a smoother less-sharp image, you can turn the focus knob in one direction (i cant remember if it is left or right..) which will set it out of a focus a little but on the horizontal axis, which works quite well (if you turn the focus knob the other way, it will set the screen out of focus on the vertical axis instead, which doesn't look good)

[buttersoft]

just be careful not to touch anything you shouldn't when adjust the focus, as the set will need to be running with your hand inside :/

[Professor Jones]

Hey,

Thanks for the replies, after dialing the G2, focus, contrast and luminosity I get a very nice image. I didn't have to set the colors after all, reducing the contrast and luminosity settings got rid of the washed out effect and made the colours more vibrant.

I have another problem left though : there is some kind of interference that slightly affects the picture, it looks like a transparent wavy pattern that is reminiscent of what you see when there is no signal on the channels. Maybe it's a shielding issue from the VGA cable or the PSU of the computer. 

[adder]

are there any ferrite beads (also known as ferrite rings or ferrite chokes) on your vga cable? if there is not, you should switch to a vga cable which has those on it, one on each end would be best but otherwise you want a ferrite bead just before the the video cable goes into your tv

https://en.wikipedia.org/wiki/Ferrite_bead

make sure the video cable is high quality shielded (meaning all the wires inside the cable are covered by an outer shield, such as a braid shield (plus a foil shield for extra protection is a good idea), and that shielding should be connected to ground so any interference trying to get in is dealt with properly (killed)).  for even higher quality cables you will find that some of the wires inside the cable such as the R, G, and B wires, are also individually shielded from each other/the other wires in the cable

https://ae01.alicdn.com/kf/HTB1S_lcRFXXXXa2XXXXq6xXFXXX5/SAMZHE-1080P-VGA-Cable-Aluminium-foil-braid-Gold-plated-Connector-1-5m-2m-3m-5m-10m.jpg

apart from that a little test you can do is if possible see if the interference changes depending on how close the pc is to your tv

another test is to try the tv plugged into one of your wall sockets in the house and the pc in a different wall socket of the house, so they are not sharing the same eg. 4-way power extension lead (you could use a long power extension lead to have either the tv or pc plugged into a mains socket in another room)

[Professor Jones]

Hey,

I checked my VGA to SCART cable, which I bought from https://www.arcadexpress.com/ and it has zero shielding : no ferrite beads and just a black PVC casing. So I thought "great, I found the culprit !" and I was ready to make a better cable, but I wanted to confirm this first. So I got my old PS1 and plugged it in using a very high quality official RGB cable (which has a ferrite bead on both ends and very thick shielding) and unfortunately the exact same problems could be seen on the image

I even tried to plug the TV directly into a wall socket and in another part of the house, with no other electric equipment close to it : no change at all.

So these experiments pretty much confirm that the problem comes from the TV itself...

[adder]

that's a shame to hear, i suppose the next step to test would be to try another crt tv just to make sure it isnt some funny interference going on inside your house rather than the tv itself ( .. i imagine the problem is the tv itself though anyway...)

i dont know what to suggest if it's the tv...  are you able to get into the tv service menu?
if so, maybe (especially if you have nothing left to lose at this point) you could try changing values of different things in the service menu to see if anything helps matters, such as turn off certain features of the tv which are not needed such as the tv tuner section etc etc
you could always write down the default values of everything in the service menu if you want to go back to the original settings after experimenting with it all
some tv brands go quite overboard in trying to stop interference by having quite a few ferrite beads inside the tv itself whereever there are wires present (such as the RGB wires etc).  i suppose you could try that (particularly try to get some ferrite beads at the end of the video signal wires before the video signals are being sent into the tube neck itself (you dont have to cut any wires; just fold a wire at some point and put it through the ferrite ring a few times).   i have had high quality monitors in the past which have had perhaps 10 or so ferrite beads at various places INSIDE the tv case to really enforce the rule of 'no interference welcome here!' ...
ps. i realise we are clutching at straws a bit at this point... but im not sure what else to suggest 

[Professor Jones]

Thanks for your help, I think the ferrite beads are my very last chance of sorting this out because I've tried everything else (including every setting available in the service menu). So I've ordered the beads and I plan to install one on the cables that run from the chassis to the RGB amplificator, and also one on each end of the SCART cable. I'll report back here after I've tried that, fingers crossed

[Professor Jones]

Just reporting back in case it might be useful for somebody : I changed the caps in the primary and secondary circuit, and one cap on the RGB  pcb at the rear of the tube. Now the image stable and the problem I had is gone. I think my quest for a CRT TV is over, the picture quality is really good (IMO of course) and all that's left to do is to enjoy it ! Here are a few pictures :

https://photos.app.goo.gl/9qwism2gVpYQUG9y8

[buttersoft]

Looks awesome. Man, everyone else's CRT always looks better than your own, i swear.

Great call by Adder though, i would never have thought to recommend adjusting the flyback based on the original post.