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Macintosh SE/30 logicboard recreation (thread revival)

GeekDot

Well-known member
I still get asked for the layer stackup, so I'm not sure if this is required to be filled in? I've not ordered boards more than two layers before, so this might be more obvious for others.
Mhh, never saw that dialog at JLC.... and I ordered many, many multi-layer boards.

While you're living in het mooie Nederland, I can offer you to sell/send you a purple, unpopulated board as soon mine arrived (if you're fine doing the populating yourself).
 

Daniël

Well-known member
That selection is optional for when you want a different stackup as defined in the gerber files.
Thanks for the clarification, JLC doesn't make it obvious that this is optional in the provided dialog box.

While you're living in het mooie Nederland, I can offer you to sell/send you a purple, unpopulated board as soon mine arrived (if you're fine doing the populating yourself).
Thank you for the offer, but given I'm in need of at least two, maybe even three boards, to populate with the components of donor boards, I can probably do with a full JLC order. Two boards I've got don't work and are pretty grotty, so I'd prefer just giving those a fresh board, and my third working one also isn't that great in shape, making me worry electrolytic induced damage might rear its ugly head sometime. Which I won't need to worry about on a clean board :D
 

TweedyF

Active member
A little late to the party, but this is so great! Thanks for all your work on this Bolle and everyone who helped out.
 

Alex Tirrell

New member
How close to a fully populated board can I get with the BOM parts and some donor parts from a regular SE? (Has anyone tried this avenue?)
 

Bolle

Well-known member
There’s nothing on an SE board that you can use for the SE/30.
Except the IO shield metal and the connectors.
 

craig1410

Well-known member
@Bolle firstly, sincere thanks for all your work and also thanks to everyone else who contributed.

I have just assembled an SE/30 using one of your boards which I had made by JLCPCB. Everything went really well during assembly apart from a couple of issues. I'm wondering if these are somehow unique to me or more general, or indeed if it's a mistake by JLCPCB.

Firstly, the 30 pin SIMM sockets I bought from RS Components don't align correctly with the pins and support pegs. The pins are correctly spaced and so are the pegs but they are relatively offset from each other which means you can align the pegs or the pins but not both. I compared the RS SIMM sockets with the ones on the donor board and the spacing is the same so I'm pretty sure it's the board that is wrong not the sockets. I'm wondering if it's best to snip off the pegs and use glue or hot melt for mechanical support or to ream the peg holes out with a suitable drill to suit.

Secondly, the metal support tabs on the ADB and Serial connectors is only a round hole when it needs to be a slot like the central one. I'm using connectors recovered from the donor SE/30 board so perhaps if I sourced new connectors then the side support tabs would be round. I'll certainly look into this.

I hope I don't sound unappreciative by providing the above feedback because I am honestly delighted with the boards. If you want to see the dimensions of the SIMM socket, it's RS product code 378-9419 and the data sheet can be found here with detailed dims. The key dimension is 9.6mm between the smaller support peg and the first contact. On my boards it is only 8mm.


Thanks again - let me know if you need any more info from me on the above.
 

craig1410

Well-known member
Sorry for the double post but just wanted to say that I just got the board powered up and booting both system 7.1 from the BMOW ROM SIMM and 6.0.8 and 7.5.5 from the SCSI2SD device. I ran a bunch of tests from Snooper and everything seems to be working except the serial and printer ports which require loopback cables to work properly. I also don't have the serial sockets fitted yet or the resistor packs or 26LS03 chips so it wouldn't be expected to work yet.

I ended up snipping off the locator pegs on the SIMM sockets and just soldered them down nice and tight. I can always put a couple of drops of super glue at the ends if I need to but honestly it's pretty solid without the pegs. I'm planning to just fit 4x16MB SIMMs and leave it alone anyway.

Just a few finishing touches required now but I am so relieved that it has basically worked first time just as @Bolle described! It was a ton of work to fit all the passives to the bottom of the PCB and it was also hard work desoldering all the components from the donor board, especially the thorough hole components due to the solder being a bit oxidised. I was also convinced I must have cooked some of the PLCC chips due to excess heat with the heat gun but as far as I can tell everything is working. I've not tested the SWIM chip yet but will hook up the floppy drive soon to test that.

Thanks again to everyone who made this possible. Once I get this machine fully working and reassembled I'll post a full update in a separate thread with photos etc. I'll also see if I can provide some updates to the BOM and give details of where I sourced all the parts. In the meantime if anyone has any questions then let me know.
 

Bolle

Well-known member
Ha, good to hear there's finally someone else with another working board. I don't think anyone else has gotten that far to actually have a booting one.
Regarding the SIMM sockets... I used whatever was in Eagles library. I think they're part of the AMP connector library. Not sure if there was a standard spacing for the support pins or not and if there was who did violate it here.
If I can find some time to draw my own SIMM socket part I'll include both possible support hole locations.
So far I only used sockets harvested from old logicboards and on most the plastic support pin came off when removing them from the donor board, so the question if they fit didn't even arise :D

Same with the Mini DIN footprints, they come with round holes for the shields in Eagle.

If someone wants to redraw both the SIMM sockets and the MiniDIN8 and MiniDIN4 connectors and send me the libraries I'll update the board with those.
 

craig1410

Well-known member
Oh wow, I didn't realise nobody else had got a board to boot yet. If I'd known that I would have added a few drum rolls and embellishments to my story! :giggle:

To be honest, since my SIMM sockets have the metal release tabs, you don't need much force to insert and remove SIMMs so the support tabs are not really essential as long as you take care to solder them down nice and tight to the PCB and obviously take extra care when swapping SIMMs. But I can confirm that both my donor boards and the RS Component sockets I mentioned seem to concur with the 9.6mm dimension but I take your point that not all vendors might be using the same spec. The part number on my donor board sockets is A-78985 3001-9007 but I can't find a match for that on the web.These are double sockets not singles though, and have plastic release tabs.

For the ADB sockets I have now ordered some new TE Connectivity 5749181-1 from mouser because my donor connectors are a bit scruffy. I have also ordered TE Connectivity 5749268-1 for the serial sockets. Mouser has PCB footprints available for these if you follow the links here. These are the parts from the SE/30 BOM spreadsheet. I do note that these have different types of support tabs so might need tweaked to fit.

Anyway, it seems rude not to post a couple of photos so here is a photo of my donor board before I started and later aborted repairs as there were just so many trace breakages and bad vias it was unviable. And of course a couple of photos of the new board in bootable but not yet complete state. My aim was to avoid installing any non-essential through hole components which would reduce access for any necessary rework to SMD components but I can go ahead and fit the remaining parts including the new connectors (ADB, Serial, PDS, DB-25, DB-19) which I'm waiting on arriving.

One last piece of advice I would give to anyone thinking of ordering some boards is to use the pick and place service for the passives on the bottom of the board. It'll save you hours and probably won't cost any more than sourcing the passives yourself. Unfortunately I understand (from this thread I think) you can only get this done for green PCBs not purple so it depends on preference. Besides that, ordering the boards from JLCPCB was trivial although I was relieved when they arrived and weren't inside out or upside down or whatever! 😅

Note: The eagle-eyed among you might notice the unsoldered joint on my analogue board connection. I just noticed it myself! This is what happens when you work on projects until 3:30am. Will fix later.
 

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robin-fo

Well-known member
Oh wow! It looks like the CPU was not socketed on your donor board. How did you desolder it? I need to do the same very soon...
 

craig1410

Well-known member
really nice work there. :D well done.
Thanks :D
Oh wow! It looks like the CPU was not socketed on your donor board. How did you desolder it? I need to do the same very soon...
That's correct, it was soldered. Removal was a challenge to say the least. I started by trying my hot air station with lots of flux, thinking that it should just fall out under gravity when the solder flowed. Anyway, I chickened out after I saw the donor PCB start to delaminate and bubble in the centre of the chip (backside of PCB). I was using the hot air station without a nozzle at 480C and fairly high air flow, just going round in circles above the pins but no joy... I suspect the ground plane is just sucking away the heat because I tried removing some of the PLCC chips by heating from the back but again no joy.

So I reverted to solder wick and manual solder removal pump and again lots of flux. It took ages but eventually I got to the point where the last few pins let go with a bit of heat from the hot air again.

Desoldering was definitely the most demanding and frustrating part of this rebuild. I'm going to get some Chip Quik low temp alloy solder next time I think, so that I can reduce the temperature during the removal phase.
 

herd

Well-known member
That's amazing work, thanks for sharing your project! When removing parts like that CPU, I've had good luck cutting it out of the PCB. If there's no reason to try and save the board, if you cut out a small square with the part you want it's much easier to heat and remove the part without overheating it or other parts nearby.

Also, I noticed that the vias are not masked. Is there a reason for this? Just curious...

It's neat to see work like this. You guys made my morning.
 

craig1410

Well-known member
That sounds like a good idea for CPU removal, thanks for the suggestion.

Re the question on solder mask on vias, maybe @Bolle can speak to that but I don't think vias are normally masked which is why on the battery bombed boards the vias get destroyed. I suspect they need to stay open to allow them to be tin plated during manufacture but I'm just guessing really.
 

macintosh2002

Well-known member
@craig1410
Thank you very much for sharing your experience!
I got a SE/30 with a leaking Maxwell battery from 11/90 which destroyed the logicboard and will place an order at JLCPCB with a green presoldered (backside) board to rebuild my SE/30.
I already started with desoldering some chips, but that's way harder than I thought it would be, especially when it comes to the soldered cpu and PLCC chips.

edit:
I'm not sure, but did you use a socket for the cpu instead of direct soldering the CPU to the board? If so, which one did you use please?
 

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