Quoted from Quench:
Are you sure you're installing the 3 batteries the right way around? You might have one installed backwards which is effectively cancelling two batteries out. Can you post a picture of this 4 slot battery holder?
wayout440 you might want to correct your battery diagrams, you have two positives connected together
1N5817 are commonly used as a battery blocking diode because they have lower voltage drop compared to a 1N4007.
I have it out and packed away, so I can't provide a picture, but the batteries were installed properly. I pulled them all out and re-seated different batteries in different slots. I did that several times.
After my post last night, I turned the game off at 2100, powered it back on at 2215 or so. All settings with the 2 slot pack installed, were saved. Left it on til around midnight and didn't turn it on until this morning at 0930. All settings were saved.
The NVRAM arrived this morning. I disconnected the battery pack from the board, installed the NVRAM, factory reset the machine and set it up again. All settings saved and good to go.
I am suspecting the diode, or some damage to the wiring when I soldered it. Here is something for consideration. When I un-installed the four slot battery pack, the wires (by my choice) were soldered to the back of the board. The 2 slot pack, I left the board installed and soldered the wires to the front of the board. It was a sloppy job because I knew the NVRAM was in the mail, and that it was only going to be temporary but it worked for the test.
Don't know why (not the sloppy part ) that configuration would have made a difference, but that is the only difference in how the packs were attached to the board, other than the number of batteries.
I copied the configuration from the 6803 repair site, for my four pack. That picture was posted somewhere earlier in this thread. That is, essentially, a picture of my setup.
btw, I'm getting a bit long-winded here but a little story that emphasizes how I tend to go about things that I have working knowledge of - always look for the simplest thing first. I have a cartoon around here on paper, from back in the 90's, that is a funny mock-up of an S3-B simulator environment. I developed courseware for the S3-B, that emulated the simulator that the pilots trained on. Anyway, it's a total mock-up, two techs (one scratching their head, the other shrugging) because they can't figure out why the damn thing won't work. And off in the corner, out of site, is a power cord laying on the floor unplugged
Some people get offended by those types of questions. I learned a long time ago, if you're going to be stupid and miss the obvious, make sure there are no witnesses and learn it going forward