Gregory's Serverthat's both sides. phew, lots of work! the next step is to photograph the top and bottom sides of the PCB. I really ought to get a scanner. 😅
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  I could just use a regular scanner, but this is a good excuse to try out this prototype Labsmore.com microscope that they loaned to me for free. (thanks guys!) i'm using Fiji/ImageJ to do the stitching. basically you go plugins->stitching->grid/collection stitching. then you pick "Filename defined by position" and then use c{xxx}_r{yyy}.jpg" for the file names parameter. and here we are in Kicad 7 using the image overlay feature. it was pretty easy to get it going but the program slows down quite a bit for large images. you'll want to scale them down. pro tip: add a scale factor in GIMP before exporting so Kicad gets the dimensions right.  got all the parts placed and many of the traces. i will need to create custom footprints; the originals are much more compact than the Kicad defaults i've been using. down to the last few traces. i'm using a multimeter to ohm out and discover what they are connected to. you can also see the faint outline of traces on layer 2 (the board has four layers). i'll need to route those next.  ahh that makes more sense. there are a few higher current connections, but more importantly, there are cuts in the ground plane! this creates a star ground at the large highlighted pad near the middle. this is the negative battery terminal (but after the current sense resistor) anyway, i could fix up a few footprints but this reverse engineering job is essentially completed. you can find the design files here: https://github.com/schlae/Thinkpad700CPower @tubetime Amazing job, would love to see a video on how exactly you go about it.  @tubetime That's amazing. What's the quote? Ah, yes. "Sometimes, magic is just someone spending more time on something than anyone else might reasonably expect." -- Teller @gogobonobo the thread explains how i did it. higher layer count boards require more invasive methods. but yes i wanted to be able to debug boards corroded by a leaking capacitor. @tubetime How did you get to these middle layers? I mean, you can measure some connections, but not get the layout exactly, unless you open it or have some 3d x-rays or something. @tubetime does kicad have any way to see multiple layers side by side? Sometimes when I have components on both sides that overlap it gets difficult even when I’m changing layer visibility. @tubetime Ohming it out on that scale is impressive. I just did the same on a board with just 20 dip ics and even that was a long task. Well, I guess it didn't help that the ohming was done remotely by a friend who was a few hundred miles away and had borrowed the card to clone while i was doing the KiCad part :) @tubetime It can't produce a schematic from the traced PCB, right? That's the kind of thing that could really cut down on the time needed to RE a board... @phaseseeker i'm starting with a schematic i already ohmed out the hard way. i'm not sure about the workflow going the other way around, i'd have to think about that. probably i'd place all the footprints first and then figure out connectivity.  |
@tubetime impressive! Did they put component names on the silkscreen or do you have a system and just name them in order of removal?