Hi, Apologies for delay in providing an update — seems work can get in the way of things sometimes.
As of now, still no change in life of the little M102 - no home screen menu, no beep, contrast runs through full range from light to dark. LCD cable tested and retested. I have validated that there are signals going to/from where I understand they should be (main ROM <> 1st 8k and other locations) and suspect that I am caught in some sort of CPU or ROM loop (as mentioned). I do have a scope on the way, and will be able to get more in-depth when it arrives and will provide more details then. As an aside, anyone every run into issues with the CPUs resistor packs? I’m testing them in-circuit and they don’t appear to meet their specs - which could be just fine, but I don’t know. Also, voltage is 4.9v on the CPU, ROM + RAM my assumption so far is that this is fine, but perhaps it really needs 5v+ and is not tolerant of even small deviations. Clearly, I’m fishing for solutions, but thought I’d ask anyhow. In the meantime, I’m practicing patience and re-reviewing the schematic. Something other than a physical connection seems to be at play. Cheers, Alan On Fri, Jul 17, 2020 at 15:42 Stephen Adolph <twospru...@gmail.com> wrote: > my 2 cents; > Worth it to see if you have valid signals at both the main ROM and at > each of the installed rams but most importantly the "top 8k". meaning the > 8K RAM that is closest to the system socket. > > if there happens to be a cracked track on the PCB, that affects the memory > subsystem, you will get this kind of behaviour. > > It would be reasonable for the CPU to end up in a loop under this sort of > condition as well. > > Yes, I have seen this happen on my fleet of laptops. Not common in > general, but more common on T102 and T200 for some reason. > >
