I guess you could consider this a pre-review of lesson 7.  I can be pretty verbose, so I’ll give you the summary first.  Do not use this kit or the XGS Pico with anything but a CRT TV. Now, for the story…

The story begins with me realizing that lesson 7 covers generating NTSC signals with software.  To say that I’ve been salivating over giving these lab exercises a whirl is putting it mildly.  Anyone who knows me knows that I live for the moment when I make a device come to life, and for me, blinking some lights just doesn’t cut it.  So, this is the big one, Elizabeth!

I try to live a fairly compact life.  I own a single television set, which serves double-duty as both the family TV and the monitor for my PC.  I bought this TV with money from my Google internship back in 2005, and even today I don’t have that kind of “walkin’ around money”, so I’d be daft beyond daft to plug my homebrew circuit into my only TV and computer monitor.  Even if it’s designed safely, why risk it?  So, I popped down to Target to get the tiniest TV I could find.  This was a nice little 7″ LCD television.  I was pretty excited.  Not only will this serve as a good test screen, but maybe I can put it in an innocuous place in the apartment and find a good use for it.  $180 later, I strapped the thing to my bike and took it home.

Today, I woke up gleefully and after some much-needed late morning sloth, I wired up the NTSC signal generation circuit as described in the Game Console Design Kit materials.  At first, I got nothing, then figured out that I hadn’t set up the TV right (which I tested with my Playstation 2) and also discovered I’d had the “brightness” potentiometer dialed so high that there wasn’t much signal to detect.  After fixing those two things, I ended up with something like what you see in this video.  It would seem the red and blue “fuzz” is just general noise, which you’d expect from a breadboard circuit like this one.  The kicker, however, is the big white bars in the middle.

I played around with it all afternoon, desperately trying to figure out what I did wrong.  It turns out that nothing is wrong with my circuit.  What I did wrong is buy an LCD TV to test this out on.  It would seem that LCD TVs do not have good tolerances when it comes to compliance to the NTSC signal standard, and I’m running headlong into a problem caused by a fussy TV and software which cuts corners in its NTSC signal generation.  You can read all about it, including a diagnosis of the issue and a handy trick for debugging a resistor ladder, at this thread on the XGameStation forums.

Originally, I felt the hacker in me rise to the challenge of cleaning up the NTSC monochrome demo.  Then it dawned on me– EVERY XGameStation program generates an NTSC signal in software, meaning that every last one of them is likely broken, too.  While there’s also the upside in that I’d be getting the fun of rolling my own everything, I feel that this would rob me of time to devote to additional topics and immediately divorce me from an existing corpus of knowledge and experience.  I’m trying to broaden my horizons, and while I might enjoy the fun academic challenge of fixing the NTSC mono demo, I’d be taking the long way around the lake to continue that way forever.

So, the long and the short?  Don’t use an LCD TV with your kit. Go get an old CRT TV and use it.  You’ll thank yourself.   Some LCD TVs are ok, so if you have one that works, bully for you.  However, some are very uptight about NTSC compliance and being even a couple of clocks off is enough to ruin it.