jsnospam@cimmeri.com wrote:
Hey, I'm just astonished that you have found more than one of these very rare conditions!Oh, believe me, if a problem exists, it finds its way into my life.AFAIK, the video sync, blanking, window timing was never changed in the ][->][+ line, so *something* weird is going on...Yeah. I'm looking at the schematic, and unlike the Mac analog board which obviously has lots of caps all over it, this Apple II design seems almost purely TTL... with one final output transistor (2N3904) prior to video out. I see no caps in the video chain at all. Michael, do transistors "leak" the same ways electro caps do?
They can leak, but in this circuit, that won't affect timing. The only idea I have is that the sync and/or video signal level is different, and that's causing the monitor to synchronize at a different horizontal phase. Kind of a long shot, but possible. Marginal monitor horizontal sync would enable this happening. Of course, there could be a logic problem that is actually shifting the "window" on the II, but that would be unusual, too. -michael NadaNet file server for Apple II computers! Home page: http://members.aol.com/MJMahon/ "The wastebasket is our most important design tool--and it's seriously underused."