Hey everyone... I'm still working on that IIe that I bought late last year and have been slowly restoring. I wrote a message on the forums back in December or so and got pointed to Joe's for a new keyboard decoder chip and that fixed that problem right away. In the months that have followed, I have gotten some more gear and setup what, back in the day, would have been an awesome system, but a new set of problems have cropped up int he meantime. I suppose that I am stuck now, and could use a little advice.
I now have the IIe enhancement kit and the new decoder chip installed. On power-up I end up getting a screen of horizontal lines (solid while every other column in 40 columns), no beep, and a halt. Maybe it is acting like what one would expect when holding control-reset when powering on? I can resolve this situation by pressing OA-control-reset and then the machine boots and acts completely normal... a simple control-reset dumps into BASIC as on would expect.
Running regular 64k software, after about 30-40 minutes, I get crazy errors looking like RAM errors...screen glitches followed by bizzaro errors where I can't even get control with a cold restart or warm restart until I let the machine 'rest'. I suspect some component is warming up on the board causing the whole thing to go bad. I have checked the power rails and get good voltages, even when these failure conditions are present. With all the cards installed, it is probably a pretty good draw on the power supply, but I don't notice any overheating or anything janky with the power... maybe I am overlooking something, but I am pretty confident we are good there. Indeed, I have these problems whether I have a full array of cards installed (Aux, SSC, Disk II, Liron, RM Microdrive/IDE controller) or not.
It would seem that I can hasten these errors by attempting to run software using the original extended 64k or the Ramworks IIII card in the aux slot, i.e., AppleWorks or the like... I haven't been able to successfuly get into Appleworks. That being said, I also have not been able to completely troubleshoot with a clean install of ProDOS versions onto a 3.5 which I know has a version-appropriate match between AW and ProDos, in other words, I am not convinced that ProDOS 1.9 running on the IDE card isn't causing problems with old Appleworks 3.x, 4.0 etc.
On the initial startup, the OA-CA-Control-Reset diagnostics run fine. When the machine is "warm" there are always RAM errors, but I can't find a consistent pattern for them (as to what chips are failed). I went ahead and socketed the RAM and tried fresh chips and got the same behavior. This was a harrowing experience, as my soldering skills have deteriorated in the last 30 years, but I seemed to have done it correctly, as there are periods, no better or worse than before, when everything works. Thus, I don't think it is an actual problem with the RAM chips... I mean, it still could be, but with all of that work and no problems for a while after booting, it seems that I am playing a zero-sum game on that front.
I took a stab and tried a spare MMU in the system... that doesn't seem to make a difference. I don't have access to an extra IOU, unfortunately. I have also reverted back to the original (unenhanced CPU and ROMS and video ROM and even the old, busted keyboard decoder) and the behavior is the same.
Just tonight, for the first time (with the original 64k expansion card loaded, not the RW4), I did not crash during the mobo and RAM tests in the IIe Diagnostics 2.1... I did get an error in the that said "Main Logic Board RAM Test Failed" with an error number(?) R90400FD, and a request to refer to the Apple Service Technical Procedures. That book, of course, was useless, saying to "replace the system board". This was on a 'cold' machine, but it was accessing the 80 column card, so.. there is that little tidbit fitting into the puzzle again... not being able to address that aux memory without causing problems.
I do have access to an oscilloscope, but I have not done a lot of deep, systematic/diagnostic probing yet to figure out what is going on... I see clock pusles on the processor and ram lines that I'd expect during normal operations. I'll have to go back and check the power-on situation... I seem to remember that the clock was suspended there until the reset went through, but I didn't write down the specifics or the pinouts (sorry-- I'll try to followup on that!) I suppose for now I am looking for pointers and ideas on how to proceed in a more logical, diagnostic manner. I sense that there may be two separate problems... the booting issue (vertical lines) and then the warmed-up RAM failures. Any takers?