Moving an RGB image so it can be centred on a tv

[omf]

I have an Area51 / Maximum Force arcade board but when I connect it to my CRT TV via super gun it is not centred and the image is partly cut off because if is past the tv edge.

 

I know some monitors have the ability to move the image horizontally and vertically by using pot's, but CRT TV's dont, or if they do it means taking the back off and tinkering with live parts which is not a brilliant idea for repetitive use.

 

just wondering if this can this functionality be replicated in a box connected on say a scart cable so it can be done to any video signal?

[DrWho198]

I don't think it would be easy to change the signal itself.

However... as you mention yourself. These pots are most likely inside your television.

And some newer CRT tv's have a software menu that is hidden to change this aswell.

You should look up your specific model and/or brand of tv and look if it has service menu's. Watch out thouch... some settings in those menus could screw up the picture.

 

Alternativly you could go for a CRT monitor. These have these settings accessible more easily.

[+Stephen Moss]

I am Not familiar with the Super Gun, have you tried it with something other than the Area51/Maximum Force boards? That may at least indicate if problem lies with the Super Gun/TV interface or the Super Gun/Area51 boards interface.

 

I am assuming the image is shifted to the right, if so it could be a sync issue although this is only speculation as I have some vague (and possibly incorrect) recollection of hearing about that happening at Tech. Although not being on the TV course I can't remember the cause, it could have been due to some delay between the Sync Separator and video processing stages. If the TV is doing any video post processing (i.e. NTSC to PAL colour conversion) that could potentially introduce enough of a delay unless such a delay is being introduce in the Super Gun and arriving at the TV as an integral part or the video signal.

 

Alternatively are you certain the Super Gun and the TV are using the same sync set up, can you switch one from using V & H sync to using Sync on Green to see if that gives a better result?

 

From what little I remember about the little I was taught about TV's/CRT's 20 years ago the pot adjustments on monitor alter the default deflection voltages on the CRT and so are nothing to do with the Video signal at all. If you could find the correspond pots inside the set you could bring them out to be externally adjustable but you could also be dealing with voltages as high as 1KV, I suspect the pots on monitors introduce the offset at the low voltage stage so I would not advise it unless you know what you are doing.

 

As for building the functionally to shift the position into the SCART cable I can't remember enough about the video signal to know if that is possible but I suspect it may be if you want to add a delay to shift the image right not if you want to shift it left.

[omf]

thanks for the information, from what i can remember, the video signal is wired directly to the board connector to the corresponding pin on a scart socket, as you say that may be incorrect maybe the sync pin needs rewireing

 

i think the signal was shifted to the left it has been a while since i plugged it in. I will get the thing out and rig it up and look.

 

i did try my 'Freeze' board but alas apart from seeing it working when I purchased it, it appears to have died on me, which is a little annoying considering it is suppose to be quite rare

 

i do have one last board that has area 51 only on it, i didn't try this because i want to upgrade it to a dual board but that's the last one i can test it with

 

my old CRT brick will not have any options for image moving in software its over 10 years old i would say, i need to have a old CRT for this board because it uses old style light guns that wont work on new flat panel TVs

 

could possibly attempt to get an old BBC / Archimedes monitor that has left / right functionality but attaching it may be an issue. ill get it out soon and pose some more information