Reverse engineering the LC II Logicboard

max1zzz

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Sep 23, 2021
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With the (hopefully) final revision of the LC 1 board and the second revision of the LC III both with JLCPCB for manufacture it;s time to turn my attention to the LCII. This was initially going to be the second board LC board I worked on before that pesky LCIII board distracted me...

The boards I am working form where kindly donated to me by cheesestraws from 68kmla for reverse engineering, Many thanks for that!

I haven't taken pictures of most of the process because it's more or less the same process as the previous two boards but here's when I'm at currently:
16-11-21.JPG

About 2/3 of the top copper is done, should only be a day or two more till this side is finished :) Then it's on to the bottom side which is always fun due to the huge amount of birdseed that's always on the bottom side.....

I'll post more updates as I work on the design :)
 

FortyTwo

New Tinkerer
Nov 24, 2021
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Indianapolis, IN
Wow, looks like you are making great progress! As an LC II owner, I am looking forward to seeing the final result. It's a shame that there is no good, non-destructive method to see the inner layers.
 

max1zzz

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Sep 23, 2021
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I finally managed to get a board assembled enough to test:
IMG_1909.jpg

I didn't really expect it to work, after all V1.0 boards rarely work out of the box however I flicked the switch and was extremely surprised to hear a clear chime! But I was getting a solid white screen.... The I realised I hadn't installed a VRAM simm, quickly installing one presented me with this:
IMG_1910.jpg

It works! :)
I can't quite believe it boots with no modifications! (well, at least it boots this far, I still need to solder the rest of the connectors and fully test it so there is plenty of room left for things to not work)
 

max1zzz

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Sep 23, 2021
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Board layout, gerbers and scans are now on GitHub:

As with my other designs these are provided under a non-commercial licence but if you are a repairer and want to offer transplant services (or have any other commercial use in mind) please contact me