Does the no-screen BASIC test work? (Cold-start, enter, B E E P, enter) On Sat, May 25, 2019, 8:22 AM Stephen Adolph <[email protected]> wrote:
> Kurt, do you have a scope? > I would certainly try reseating any socketed parts. Main rom is socketed > for sure. > Then I would start at the clock and work forwards. > * verify the CPU has clock > * verify the CPU control lines are toggling > * look at the address and data lines for toggling and level > > if that all looks ok then, pin by pin on the main rom, check for toggle > and level. > again for the ram modules. > to make it easy remove as many ram modules as you can. > > check DC on the power supplies of course. > > On Fri, May 24, 2019 at 8:41 PM Kurt McCullum <[email protected]> wrote: > >> I've got two NEC 8201s that are both dead. I'd like to get them up and >> running again. Especially the one with the Japanese keyboard. Has anyone >> put together a list of what to check to diagnose where the problem might >> be. I have done the power supply test from the service manual and the CPU >> seems to be correct but I'm not sure where to start. Both units turn on >> with a blank screen. >> >> Kurt >> >
