ALPHA REV G SCHEMATIC

All information relating to the Alpha plus all the WIP threads etc.
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exxos
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ALPHA REV G SCHEMATIC

Post by exxos »

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

800G.png

DOWNLOAD ZIPPED
800G.zip

FIX HISTORY (SCHEMATIC)




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.

gpcb.jpg
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rubber_jonnie
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Re: ALPHA REV G SCHEMATIC

Post by rubber_jonnie »

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.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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exxos
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Re: ALPHA REV G SCHEMATIC

Post by exxos »

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.

fh.jpg
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