exxos's Atari, Amiga & retro forum

This is the original Alpha schematic with most of the current known fixes/changes..


DOWNLOAD ZIPPED
FIX HISTORY (SCHEMATIC)

• Some of the jumper pads removed as deemed unnecessary.
• HSYNC fix https://www.exxosforum.co.uk/forum/viewt ... 1185#p9963
• BR pull up fix https://www.exxosforum.co.uk/forum/viewt ... =10#p10084
• 5x resistor fix https://www.exxosforum.co.uk/forum/viewt ... =20#p10098
• VIDEO socket fix https://www.exxosforum.co.uk/forum/viewt ... =20#p10279
• 16MHz buffer fix https://www.exxosforum.co.uk/forum/viewt ... =30#p10361
• GLUE Dataline fix https://www.exxosforum.co.uk/forum/viewt ... =30#p10524
• MFO pull up fix https://www.exxosforum.co.uk/forum/viewt ... =30#p10544
• RAM RW fix https://www.exxosforum.co.uk/forum/viewt ... =30#p10613
• KB connector missing gnd pin8 fixed
• 1772 IRQ typo fix https://www.exxosforum.co.uk/forum/viewt ... =40#p10656
• KB resistor fix https://www.exxosforum.co.uk/forum/viewt ... =40#p10675
• ACIA databus fix https://www.exxosforum.co.uk/forum/viewt ... =50#p10695
• Floppy pull up fix https://www.exxosforum.co.uk/forum/viewt ... =60#p10751
• Added buffer to MONO output.
• Fixed common name "RD" between 1772 & 232 circult https://www.exxosforum.co.uk/forum/viewt ... 374#p11374
• Changed reset capacitor to 47uF to increase reset time as was causing issues when booting up.
• Changed 8 pin XO to 14 pin.
• PLANNED UPDATE for 1772 BUS SHORT FIX https://www.exxosforum.co.uk/forum/viewt ... 641#p11641
• PARALLEL PORT FIX https://www.exxosforum.co.uk/forum/viewt ... 032#p12032
• VIDEO BRIGHTNESS FIX https://www.exxosforum.co.uk/forum/viewt ... 063#p12063

The BGACK pull up fix wasn't actually needed, it was another side of a jumper pad, so wasn't showing up in the diagram when I looked before..
https://www.exxosforum.co.uk/forum/viewt ... =10#p10086

Some resistors have been moved to RP5 (new resistor pack). New RP near 1772 for pull ups (3 seperate resistors moved)


FIX HISTORY (PCB)

(bare in mind nothing in this PCB is routed. Connectors moved may not be 100% but as close as I can tell )

• PSU holes should now be correct
• MIDI & Cartridge posts moved upwards, should now be correct
• All back row ports (aside from serial) have been moved to the right and adjusted. They all should now align.
• MIDI connectors now have "dual holes" to fit both styles.
• Added floppy mounting holes.

I still have a LOT of holes to add , plus floppy posts etc.. this will be ongoing for some weeks most likely.

Ahh, awesome, I was hoping this would all end up in one place, with a bit of luck I can get working on mine again soon.

Added floppy holes... very hard to get it 100% as having to print out on paper to check which isn't ideal. Really could have done with a blank PCB... BEST has some, but didn't get anywhere like normal, only takes paypal :roll:

Saying that, I got some duff boards, I need to take some connectors off for the STF anyway.. So will probably heatgun the board to death and remove all parts from it so I got something flat I can measure against properly.