(11-01-2021, 11:31 PM)admin Wrote: Check to make sure that your solder joints are good at the 8 pin video connector, as well as the VIC-II chip.
The 74LS629, MC4044, and 74LS74 along with the crystal (and of course VIC-II) are responsible for the video output. Check all of these to make sure that they are inserted in the proper direction... in fact, check all of the chips to make sure that all of the notched at facing towards the rear of the board.
Making incremental progress... I have a flashing dead test screen now... Albeit with all ROMs and both CIAs removed.
I had been trying to work with a GAL PLA and then a PLAnkton, but wasn't having luck with either.
Then I realized that the BOM wanted a 82S100, rather than a 906114-01, so I managed to dig up a working one.
Next, I took a look at the joints on the 8-Pin circular DIN connector, which all appeared to be fine, but then I realized something that I wasn't expecting.
The angles on the upper-most pins appeared to be off. To verify this I tried another video cable and sure enough it didn't fit properly.
It turns out that the pins were organized in more of a "O" shape than an "U", so I wound up replacing the connector with one that fit my cables better.
I was finally able to see video activity in the form of a power on flicker (whew hoo!), but the screen was still black (uhg!).
I removed all of the ROMs and both CIAs, and on the next boot, Dead test finally started to give off some flash codes.
Now, I just need to retest all of my chips... I'll need another time window to get into all that.
Thank again for the suggestions.