You might want to invest in a Logic Probe, old school debugging :) That would give a good indication as to whether or not the lines are working correctly also much easier to use than a MM. They are quite cheap these days, I use a Micronta Logic probe from log ago.
On 4/6/18, 8:48 PM, "M100 on behalf of Greg Swallow" <[email protected] on behalf of [email protected]> wrote: >Cold Boot (CTRL-Break-Reset) has been done multiple times. As well as >complete power down, including Mem Power and removing batteries. Tracing >I can do and difficult or not. I am working with this thing open and in >parts. I was testing in case, but the markings are then facing the back >of the M102. To see VDD, VEE, and VB marking and test properly I pulled >the motherboard out with no display or keyboard attached. I'll try to >make room to get in all on a mat, but I am short on space. Whatever needs >to be done, I'll try and do appreciate your help. > >Thanks, > >GregS <>< > >----- Original Message ----- >From: "Fugu ME100" <[email protected]> >To: [email protected] >Sent: Monday, June 4, 2018 8:35:36 PM >Subject: Re: [M100] Model 102 Black Nothing After Y2K ROM install > >OK they look good. The VB = +3.6V (approx) when powered down, it is the >backup voltage for the RAM. > > >It would appear that all the voltages are correct. The next step would >be to start tracing out the address, data and control lines to make sure >the buffers etc are all working when the unit is powered on. Hope to >find a buffer that does not work or other failed chip or even a failed >joint. It can be done with a MM but not easy. > > >A cold boot might be worth trying if you have not already done so. >
