LaPorta Posted August 26, 2020 Report Share Posted August 26, 2020 Bolle, seeing your photos truly makes one see just how much damage battery acid causes, and just how damn near impossible it would be to repair such damage externally. Alternatively, however, if you guys scan this stuff in at each layer and make a diagram of what goes where, then the poor soul looking for the other end of a rotted trace actually will have a shot of bypassing it if he knows where the heck the other end is. Quote Link to post Share on other sites
quorten Posted August 26, 2020 Report Share Posted August 26, 2020 Looking pretty good, with a few more photos someone would be able to run and do another PCB layout for the Macintosh SE/30 main logic board! No need to wait around for the Macintosh SE boards to be finished. Mentioning that, it would also be really helpful for making improvements to the redrawn Macintosh SE/30 schematics. I noted elsewhere in this forum I started making improvements to fix some of the errors pointed out in the previous versions. Quote Link to post Share on other sites
ajacocks Posted August 26, 2020 Report Share Posted August 26, 2020 Wow, this is so amazing! I’d also like to build one of these prototype SE boards. - Alex Quote Link to post Share on other sites
techknight Posted August 27, 2020 Report Share Posted August 27, 2020 (edited) On 8/26/2020 at 5:08 AM, Bolle said: Had some time to grind away at one of my spare boards: Going all the way down to the inner layers is going to be an absolute pain in the back. I'll need to stock up on wheels for my grinder first. Also it looks like the additional signaling two layers are right in the middle of the boards hidden under yet another set of VCC/GND plane layers. Yea, I know. You almost need a milling machine. Like what they use for doing engine heads. If you know the layer depths, you could program the machine and setup a routing bit and vacuum nozzle head and let it rip. Edited August 27, 2020 by techknight Quote Link to post Share on other sites
Bolle Posted August 27, 2020 Report Share Posted August 27, 2020 Getting the board stuck down evenly would be a challenge though. I do have a DIY-hack CNC mill and in theory the step size should be accurate enough to take off a layer. I guess it’s worth a try. I have enough dead boards here to play around. In the end careful grinding might be the best option though I think. Quote Link to post Share on other sites
wanderingjew Posted August 27, 2020 Report Share Posted August 27, 2020 If you want to get a look at the inside layers of a PCB, you *can* use a small CNC mill with a small step size. This is probably the best example of that: https://www.youtube.com/watch?v=iV4LJX1HdPk However, there's a significant drawback going the CNC route if you don't have it perfectly flat. Half of the board will have the traces you're interested in, while the other half will cut too deep or too shallow. There's a lot of fixturing needed for this project. I have heard of people going to a machine shop and using a surface grinder which would be a very good option if you could bond the PCB to a flat piece of steel (for the magnetic clamping). Alternatively, you could also find a machine shop with a _huge_ lapping machine. That would give you the ability to cut perfectly perpendicular through the plane of the PCB. Quote Link to post Share on other sites
Kai Robinson Posted August 28, 2020 Author Report Share Posted August 28, 2020 SE/30 stuff, i'll break out into a separate thread, so we can concentrate on the SE/00 board here - sorry if i've been quiet, been enjoying a few days 'staycation', visiting friends etc. I'm back home tomorrow - so will get PCB's shipped out on Monday. Quote Link to post Share on other sites
Bolle Posted August 28, 2020 Report Share Posted August 28, 2020 (edited) I guess this is as good as it gets... oh boy what a mess. At least you can see both signal layers so I don't have to bother and get to the other side as well. Damaged some traces but together with the schematics it should be easy to reconstruct those. Edited August 28, 2020 by Bolle Quote Link to post Share on other sites
Kai Robinson Posted August 30, 2020 Author Report Share Posted August 30, 2020 I am back from a week long staycation, and I have to say the new boards look even more amazing than the first batch did! So far the rear i/o power seems good and the GND and +5v for the 68000 and 74ACT257's is now there, along with the correct GND and +5v for the floppy and scsi, now... Just need to build one this week - they look amazing with new SIMM sockets, too! Quote Link to post Share on other sites
pax Posted August 30, 2020 Report Share Posted August 30, 2020 Spectacular! Quote Link to post Share on other sites
ravuya Posted August 30, 2020 Report Share Posted August 30, 2020 That looks incredible. Quote Link to post Share on other sites
rplacd Posted August 30, 2020 Report Share Posted August 30, 2020 Gorgeous. You have no idea how relieved I am to see the metal clips on the RAM sockets! Quote Link to post Share on other sites
techknight Posted August 31, 2020 Report Share Posted August 31, 2020 On 8/30/2020 at 10:29 AM, rplacd said: Gorgeous. You have no idea how relieved I am to see the metal clips on the RAM sockets! Yea, I know, right? Quote Link to post Share on other sites
Kai Robinson Posted August 31, 2020 Author Report Share Posted August 31, 2020 Okay, been at it for 14 hours and this is as far as I've got... Need a few more parts to finish it off! My eyes have gone funny...! Quote Link to post Share on other sites
CC_333 Posted August 31, 2020 Report Share Posted August 31, 2020 Looking good! Hopefully this one will work! c Quote Link to post Share on other sites
demik Posted September 1, 2020 Report Share Posted September 1, 2020 Just finished reading all 10 pages. Thats just impressive work. Nice skills ! Quote Link to post Share on other sites
Kai Robinson Posted September 2, 2020 Author Report Share Posted September 2, 2020 ....and this batch of boards is dead, too. I'm pissed off right now. The inner copper layers of the rear I/O are bridged. I've checked the files i sent and there's nothing there that can cause it. +5v and GND are bridged somewhere. Even with no components, it's bridged. Quote Link to post Share on other sites
Franklinstein Posted September 2, 2020 Report Share Posted September 2, 2020 That's really unfortunate. Could one of the vias have caused it, or maybe one of the larger lugs at the rear of the board? Maybe if you have a sensitive tone generator and pickup you could potentially trace out the current flow to try to find where it connects or at least narrow your search a bit. Quote Link to post Share on other sites
Kai Robinson Posted September 2, 2020 Author Report Share Posted September 2, 2020 I'm looking over the board at serious magnification - DRC checks, test pads show no components bridging - it's a manufacturing issue. Nothing is connecting anything incorrectly. If it were a component, that'd be understandable, but this is a board level defect with the internal layers. If you cut the bridge connecting the ground planes, the rest of the board has no issues, its just the rear I/O - i'm going to totally re-do the cutout areas, just in case, and make them intersect stuff. I may relocate some of the filters by 39.6875uM just to make them clear the 'split' just right. Quote Link to post Share on other sites
Bolle Posted September 2, 2020 Report Share Posted September 2, 2020 Where did you have them fabbed? I never had any actual fabrication defects ever. All boards go through electrical testing (at least at JLCPCB where I usually order my boards) so it really shouldn't happen at all. You could try to connect a bench power supply and run a whole lot of power through the board to see where it starts to turn black to find out where the short is. Quote Link to post Share on other sites
Kai Robinson Posted September 2, 2020 Author Report Share Posted September 2, 2020 Unfortunately, the bench power supply is the thing i lack. A FLIR camera would also be good. They're being fabbed at JLCPCB - I'm happy to release the gerbers to someone if they want to check them over? Quote Link to post Share on other sites
techknight Posted September 2, 2020 Report Share Posted September 2, 2020 I have gerber utilties that I use to verify my board designs, so you can send the gerbers my way. You know its in the I/O section in the rear? itll give me a place to start so I dont go crosseyed. Quote Link to post Share on other sites
Kai Robinson Posted September 2, 2020 Author Report Share Posted September 2, 2020 Yes - confirmed, there's no short outside of the split I/O section at the rear - , if you remove the link between them, the board will power up in the chassis as previously. I'll DM you with the Gerbers. Quote Link to post Share on other sites
techknight Posted September 2, 2020 Report Share Posted September 2, 2020 Ok Quote Link to post Share on other sites
techknight Posted September 2, 2020 Report Share Posted September 2, 2020 (edited) I found your problem. Soon as I turned on the board outline, I saw it. You dont have the proper stops for your shielding holes. See here: Edited September 2, 2020 by techknight Quote Link to post Share on other sites
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