Ok I powered on and get a stable white screen, so troubleshooting is the next thing to do. I suppose in a way it's good,as I'm generating a display of some sort, and it's nice and bright.
But I had a bit of an "Oh crap" moment too. Pin 38 (GND) on the cartridge port goes up to R13.Somehow the tails for R13 and R919 got pushed together and shorted, and when I plugged in my diag cart, it burned out the track down near the cartridge port.
Normally I put resistors back to back so this can never happen, but for whatever reason, I didn't.
It's not the end of the world, as it's one track and I can put a bodge wire underneath to repair, but I'm kicking myself.
Resistor will get moved later so this can never happen again. EDIT now repositioned and bodge wire installed to reconnect pin 38 of the cartridge port
On a positive note, the diag cart is fine. Always trying to find a positive......
I'm off to the shooting range later, it's a good place to chill out and think about my strategy for troubleshooting (Starting here: viewtopic.php?f=78&t=2362
I have a new scope arriving this week, using my Hantek USB device and laptop is quite impractical because of my small work area, so the new one will make my life a bit easier. The Hantek was good as a starter scope, but I need better now, especially as I'm also working on the Mega 4.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...