Problems with new video mod

leahkim · Post by **leahkim** » Mon Dec 19, 2005 3:42 pm

I built a portable Atari per Ben's book (using the Casio screen), but I wasn't very happy with the image. The colors were very good once I tweaked the mini pots and the CTP, but it was very wavy on the edges, there were tons of interference lines, and it wasn't at all stable. Warlords would give me lots of vertical rolling, and the image would freak out anytime a bright flashed showed up on the screen (like when someone dies in Warlords).

So, I decided to try Ben's new video mod. Now, the image is rock solid stable, but the image looks way too bright and washed out. The colors are hardly distinguishable.

I rechecked everything and I think I built it exactly as he shows in the schematic, but it still looks bad. I turned the brightness all the way down on the TV, and it's still very washed out looking. Is it possible I hooked the transistor up backward, or would this give me a different symptom?

I'm an electronics newbie, so I don't know where to start fiddling with resistor values, etc. I have a multimeter and my resistors that I "built" in series seem to be of the correct value. Please help, anyone!!

Tromoly4130 · Post by **Tromoly4130** » Thu Dec 29, 2005 4:25 pm

This was pulled directly from the mod page:

"To adjust the video signal you can vary the types of resistors you use (the ohms) From what I saw using too low of values "overloaded" the signal and either scrambled it (when using too low of resistors for the TIA pins) or washed it out to black and white (when using a lot less than 450 ohms for the +5 volts in)"

Try changing a couple resistor values and see if anything happens. Good Luck!