Kai Robinson Posted January 9 Report Share Posted January 9 For now this is mostly going to be a placeholder, until the SE boards are finished, but as the title explains, this is designed to save as many Mac Classics as possible. So many have died thanks to the stupid PRAM battery on the board. These are 4-layer PCB's with a mix of through hole and SMD component. You will need at bare minimum, a soldering iron, hot air soldering station, desoldering station and a decent selection of hand tools. So - how do you reproduce a PCB? First, get a Mac Classic PCB - in my case a 'dead' board from Mr Adrian Black! Then, you get to work desoldering. Literally EVERYTHING. Not a single component must remain! However, 30 year old solder and my ZD-915 desoldering station caused a handful of through holes to just pull out of the board, or some traces would come up with it. I found that pre-heating the joint, with a little flux (AmTech RMA-223), would make the solder melt a lot cleaner when you use the ZD-915 desoldering gun. You must use a lot of heat on these boards. For hot air - i recommend a temperature of 360*c and a flow rate of 4.5 - you must use the right tools for removing the PLCCS - use the A1137 and A1138 nozzles for the larger parts - and the wide round nozzle for smaller 'birdseed' and SOIC parts. For through hole joints that have been corroded, you must flood the area with flux, heat from both sides, then try and move the pin using a soldering iron (i find 420 degrees C suitable, with a standard flat tip) before trying to use the desoldering gun. Sometimes it won't always come out of the joint, in which case reflood with flux, and attack it with desolder braid. I use 2.0mm GootWick, which is fantastic stuff (thanks to Louis Rossmann for the recommendation). Preheating the board with hot air works wonders. Speaking of hot air - for SMD parts - be liberal with flux and don't just keep the hot air on the part - you want to move it around the part, on the legs and keep a little pressue on it with some tweezers - don't force the part to move, it'll loosen when the temperature is jsut right. You want to save basically everything bar the SCSI and Floppy connectors, ROM Socket and the 'birdseed' (SMD Resistors, Capacitors, Transistors & inductors). Once you've saved all those parts, it's time to get scanning! 800 to 1200dpi on your scanner. As the Classic PCB is rather smaller than a sheet of A4 paper - it'll all fit without having to merge mutiple images. There will be a more to follow...but any questions so far? Quote Link to post Share on other sites
rplacd Posted January 10 Report Share Posted January 10 (edited) Kai – glad you're taking this on! If you ever want another badly Maxell bombed Classic LB, I'd be happy to send you one via first class parcel, on my tab. Edited January 10 by rplacd Quote Link to post Share on other sites
Kai Robinson Posted January 10 Author Report Share Posted January 10 @rplacd actually - the most beneficial thing would be to strip and sand the board so the inner layers are visible, and scan them! I live in a shared flat and have no 'outside area' that's suitable for it, really. At the end of Sunday - this is how much i've managed to get done of the top layer; Quote Link to post Share on other sites
Bolle Posted January 10 Report Share Posted January 10 (edited) Are you sure this is just a 4 layer hoard? Pretty sure everything was 6 layer by the time the Classic came out. Edited January 10 by Bolle Quote Link to post Share on other sites
rplacd Posted January 10 Report Share Posted January 10 2 hours ago, Kai Robinson said: @rplacd actually - the most beneficial thing would be to strip and sand the board so the inner layers are visible, and scan them! I live in a shared flat and have no 'outside area' that's suitable for it, really. I have no idea how to do this – but if anyone wants to give this a try, contact me. Quote Link to post Share on other sites
anthon Posted January 10 Report Share Posted January 10 (edited) Kai, since you're doing a lot of this type of thing, you might consider investing in an IR pre-heater. I have a T8280. Makes this sort of thing a lot easier, and this Chinese one only costs about $100 shipped. (Preheat the entire board to a temp somewhat below your hot air temp, then the hot air gun has a lot less work to do. Should cause less heat stress to the components as well.) https://www.ebay.com/sch/i.html?_nkw=ir+pcb+preheater Edited January 10 by anthon Quote Link to post Share on other sites
Trash80toHP_Mini Posted January 10 Report Share Posted January 10 My ME brother told me the way to analyze the layers of a board is to set it up perfectly level and encase it in epoxy. In that state each layer is easily milled away and scanned. I'd told him I'd tried sanding and it wasn't a very effective approach if if done by hand. That was 30 years ago, cast resin should make it easy these days . . . assuming you have access to a milling machine. Quote Link to post Share on other sites
anthon Posted January 11 Report Share Posted January 11 The milling machine isn't a problem at all -- every self-respecting maker space will have one. I don't understand the cast resin step though. What would be the process for that? I'm definitely tempted to do this. Quote Link to post Share on other sites
techknight Posted January 11 Report Share Posted January 11 Dang. I thought the SE/30 was next. Thats what I desperately need. Quote Link to post Share on other sites
Kai Robinson Posted January 11 Author Report Share Posted January 11 @techknight SE/30 is on the bench now, i can't help myself! @Bolle did you manage to image the inner layers? Quote Link to post Share on other sites
Bolle Posted January 11 Report Share Posted January 11 2 hours ago, Kai Robinson said: @Bolle did you manage to image the inner layers? Kind of at least... Altough we are slowly getting into working on a replacement logicboard. We‘re going for a more classic PCB design workflow. We‘ve got all the needed Apple custom and non-standard ICs in Eagle and I should start redrawing the schematics sometime soon. I will cross reference the schematics once more with the scans of what is left of the inner layers after grinding away like crazy at one of my boards. I will implement options for using both modern replacements and original ICs where possible... VRAM comes to mind as well as the video ROM, 29F040s right next to the ROM SIMM, possibly RAM as well. Quote Link to post Share on other sites
Kai Robinson Posted January 11 Author Report Share Posted January 11 Would you mind sharing the 1200dpi scans of the inner layers with me, so i can try for a 1:1 layout? VRAM is easily available on UTSource as NoS, as is DRAM for making 30-pin SIMM's, i have 50x PCB's for 30-pin SIMM construction, and new PE Connectors SIMM Sockets. Quote Link to post Share on other sites
Kai Robinson Posted January 14 Author Report Share Posted January 14 Top and bottom layers provisionally done Now, the inner layers should be just ground and power - but i fully expect there to be some surprises. I know there's talk of these being 6-layer boards, but honestly, these are cost reduced SE's with no PDS slot and only 1 ADB, the schematic isn't all that complicated and that's the other thing, we have the schematic! Would anyone like to take a look at the Sprint Layout file so far? Quote Link to post Share on other sites
demik Posted January 15 Report Share Posted January 15 (edited) Good job again. I think the NCR ship is repleacable but the Zilog Z53C8003VSG which is still in production. Pins looks compatible ! They might be a compatible SSC still produced too. Can you give us the PN ? Should be a 8530 IIRC. I will take a look Is the BBU compatible with the SE one ? Edit: found it Z0853004AVSC. Z85C3008VSG looks pin compatible - SCSI: https://www.mouser.fr/ProductDetail/ZiLOG/Z53C8003VSG/?qs=FsLZlD%2B%2Bd9cJEZW2nIhyXQ%3D%3D - SCC: https://www.mouser.fr/ProductDetail/ZiLOG/Z85C3008VSG/?qs=z96q%2FFFR6qb6cf17DanQqQ%3D%3D Edited January 15 by demik Quote Link to post Share on other sites
mogs Posted Saturday at 05:17 AM Report Share Posted Saturday at 05:17 AM I have a classic LB I failed to revive after recapping, could be a candidate for contributing to this effort. I don't currently have any hot-air gear, might be a good excuse to get some. I've done some pretty epic stuff with just a soldering iron, but removing a 68000 intact might be a bit of a stretch. I have an idea regarding inner layers involving a local commercial third party, but I should probably talk to them first before saying any more on that. Quote Link to post Share on other sites
Kai Robinson Posted Saturday at 08:02 PM Author Report Share Posted Saturday at 08:02 PM @mogs Get the PLCC nozzle and some AMTECH RMA233 flux - it'll make things a lot simpler. I'll await your inner layers idea - consider my curiosity suitably piqued Quote Link to post Share on other sites
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