NTSC_colorbars.spin Trouble

andrus

Hello,

I have been working with Eric Ball's NTSC_colorbars.spin.

I wired up an RCA connector to my Proto Board as follows:

RCA Tip
  |
  +----1Kohm--100ohm---p12    (1.1k?)
  +----560ohm-------------p13
  +----220ohm--47ohm----p14    (267ohm ~ 270ohm?)

However the display on screen runs diagonally as in the pictures I have attached. Furthermore, when I leave my USB cable in after programming the board, if I touch the end of the cable it sort of resolves the image on-screen to some extent. Moreover, if I touch the usb cable to a contact on the TV set, such as the alternate RCA plugs on the front the image stabilizes (also in the pictures).

What's going on here? The USB cable is almost like an antenna when attached, and when I unplug it the TV signal looks like grey diagonals.

Thanks,
Mark

potatohead

Just to be sure, have you run the graphics_demo.spin that comes with the Propeller tool?

If the results are the same, are you sure your ground loop is solid?

Have you verified your cable doesn't have shorts, or a high resistance circuit path?

Do other video sources operate properly with that TV?

Phil Pilgrim (PhiPi)

You've only got three wires going to your video resistor board. You need a Vss wire, too, to connect to the shells of the RCA connectors.

-Phil