Battery reads about 3.2vdc, and I tried a fresh one to be certain. I traced back each lead of the DS12885 and all show continuity. I replaced the 74LS32 and 74LS02 that do the address decoding, and also tried "74F parts with no improvement. I swapped 8088-1 processor, and also dropped the clock rate to 5mhz. I've added and removed wait states for I/O. I've resoldered the entire board.
My only thought at this time is that perhaps I have a bad batch of xtals. I've ordered a few replacements to try. Ah well, it has to be something simple! - Gary On Wednesday, July 16, 2014 3:43:28 PM UTC-4, Vince Mulhollon wrote: > > Battery voltage pin? From memory that part was like that famous memory > controller chip that got all wound up if the battery voltage was wrong. > And it was picky, none of this connect to Vcc stuff, it had to be almost > 3V, exactly, or it was super unhappy. If its oscillating it must be OK-ish > unless the battery is super low. Maybe just barely enough to oscillate but > not work... > > Some kind of lockout circuitry would get confused, like the delta between > Vcc and Vbatt had to be about two volts or it assumed power was lost and > wouldn't talk, even if Vcc was a perfectly good 5V. So a dead battery at > 1V means no talking even if you'd think it should talk because Vcc is a > perfectly good 5V. > > Thats all I got on that chip. > -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
