is it possible to adjust the picture size of a composite video signal?

[phreak97]

is the horizontal and vertical size of an image controlled by the sync? or is the sync just a clock signal that the tv turns into sawtooth waves?

basically i have an arcade machine which outputs black and white video through one line, the monitor in the cab was dead, so i put a colour tv in and plugged the pcb into the composite input, it works fine, but it's stretched off the screen..

i dont think i can do anything about it outside figuring out how the monitor can be adjusted.. right?

[viletim]

The sync signal is only to syncronise the TV's internal oscillators. I'm sure you've seen what happens when the horizontal or vertical isn't in sync with the video. The only thing you can change by fiddling with the sync is the picture position. Everything else (size, brightness, contrast, etc) must be changed by processing the video signal or adjusting the TV. Most TVs made in the last 15 years are adjusted in service mode with the remote control.

[phreak97]

yeah thats what i thought..

I've got a sharp CX-51G3 (SP-61 chassis) and i need to adjust the size.. i'm havning no luck whatsoever finding any information on it..

any ideas?

[viletim]

You could always use the hack 'n' slash method of putting a resistor in series with the vertical coil and an inductor in series with the horizontal.

[phreak97]

what kind of value inductor am i after? i can use a pot for the vertical.. but i dunno what to get for the horizontal, and thats the one that needs adjustment the most

[NeWmAn]

Don't know if it is what you need, but check this page anyway: http://therealbobroberts.net/width.html

[phreak97]

I talked to viletim on msn last night and he helped me find a decent pair of components, so it's all done and definately works with his method for both horizontal and vertical. i might also try this cap method for one of my other games which needs the screen width to be wider, which cannot be achieved with an inductor.

thanks!!