Article by Harry McCracken?Note: In some countries, including those in the European Union, you need permission to use a picture and it is not allowed just to copy and paste whatever you find online. For this reason you find only a link as long as we don't have a written permission.
The image in McCracken's article shows a unique motherboard with some unique components.
From the image, it looks like originally that regulated + 12 and - 12 was provided to the edge connecter. The production unit supply unregulated +12 and -12 to the edge connector. Woz doesn't remember any of the details surrounding those changes.
The mainboard is very different from the production units. The 6800 area is populated. There is no switch board above the 74154. No connector. Orange capacitors. The logo is different. Chips are arranged the same way like in the production units but trace lines are very different. For unknown reason it was changed. According to screenshots the prototype was working.
The current location of any of these pre-production boards, if any still exist, is unknown.
Woz indicates that there were probably about 3 prototypes made to verify the board layout.
They were not flow soldered
Woz isn't sure, but they were probably soldered by Steve Jobs, though Woz may have done the soldering
Unique mainboard. Prototype.
Nov 17, 2018: Components (shortlist). Components. State. Description