The Leapster Explorer, a Linux-based children's handheld, is the follow-on product to the Didj. The Explorer runs the same ARM9-based SoC as its predecessor - one of our first tasks would be to uncover the Explorer's hidden TV-out mechanism.
I managed to overvolt my first Explorer by sending 5v into the USB host pins just days after I bought it. So, I purchased a second unit and dedicated the dead unit to 'science'. After desoldering the mainboard, I was able to trace from BGA grid A2 (Video) to the test pad TP30 '-Right'.
On my second Explorer, I soldered a short length of wire to TP30 and another to ground (cart socket), connected the ends to a composite connector, and modded the case.
I then used a 75 Ohm resistor as a filter - a simplified variant of the filter originally used in the Didj TV Out hack (no capacitors needed) - hooked up the oscilloscope, and got a good video waveform:
And a decent picture on my little test monitor.
The GBA emulator we recently ported works fine on the TV too - that first picture at the top of this post is from Castlevania...
Updated TV-out steps covering Didj and Leapster Explorer are on our wiki (full mainboard scans too!)
Thanks and greetz to everyone on #Didj (irc.freenode.org)!