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Macintosh SE/30 logicboard recreation (thread revival)
- Thread starter Bolle
- Start date
thanks man, with everything already in the cart... in the end I couldn't help but doing it
BTW is this really everything needed, or should I check the BOM anyway and find which missing parts I would still need?
In case other people would be interested, notice that some of the listed components in the cart are marked "END OF LIFE", so...
better safe than sorry.
Now back to me: I have a spare board which has been hanging around for a couple of years, I have a spare battery bombed SE/30 in need of a new board, I will get the parts... I guess it's really time to do this - even if I really feel I will need some help. Wish me luck
thanks man, with everything already in the cart... in the end I couldn't help but doing it
BTW is this really everything needed, or should I check the BOM anyway and find which missing parts I would still need?
It depends! I don’t know what you need. Each build is slightly different depending on what your donor board comes with. The Mouser list I put together includes as many newly manufactured parts as was possible to source. In particular it should have all the small SMD parts on the top side, as well as things like the PDS connector and serial/ADB ports, but is notably missing RAM slots and an external floppy connector. The PLCCs and DIPs you’d be expected to bring over from your donor board. Sometimes battery leakage means that the RTC is a complete goner, in which case an ATTiny85 clone can be made up.
Good point, I’ll have a look at the cart and see what needs updating.
Now back to me: I have a spare board which has been hanging around for a couple of years, I have a spare battery bombed SE/30 in need of a new board, I will get the parts... I guess it's really time to do this - even if I really feel I will need some help. Wish me luck
Good luck
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They're the F240 (RAM buffer?) and SN75175 (serial line driver) chips. They're indeed scheduled to cease production.
Ouch.. from where do you know that?
Here…https://tinkerdifferent.com/threads/texas-instruments-discontinuing-a-lot-of-ics.3190/#post-37526
Kai just references the 75175 so maybe I’m wrong about the F240. (Although both say end of life on Mouser, so it’s not an unfair assumption).
I see you replied to that thread asking for verification, so this response probably won’t be adequate either
Can you please provide a link? Because I have considered that thread on TD as fake news…
(do you really care about that if it is hand soldered anyway?)
Thanks for the info, didn't realise the reel version is unaffected. I've updated my cart with the SN75175DR. Yes, annoying about the F240 - is the ABT240A fully compatible?
Nearly finished another build – got it booting tonight after a hiccup with UH7. This one's an old Rev 2 board that came to me partially assembled.
So here's my progress on my reloaded board.
I opted to reuse as much as possible from a board that was untested as it had capacitor and battery damage.
I was going to reuse the ROMs from the damage SIMM (was mainly around the contacts area) and foolishly assumed that the ROMS from the SIMM were the same as the socketed ROMs on the reloaded board - but alas that is not the case. So the ROMS are the only ICs which are "new" freshly burned (and verified) by my Mini Pro TL866.
So on the reloaded board, I socketed everything that was ...ahem... socketable. The reasoning was that eventually I would do more boards and could use this initial board to test all IC components.
I found the sockets a bit of a bother and cut away the bottoms to solder them on to the board. The bottom of each socket has a non-conductive card of a similar thickness to keep the IC at the correct height when inserted.
I've carefully checked and sounded out the ROMs and FPU to the CPU on my meter and scope.
The CPU, video rom and PALS HAVE all been tested as working on another SE/30 that happened to have all these ICs already socketed.
Does this look like a Video RAM issue?
I opted to reuse as much as possible from a board that was untested as it had capacitor and battery damage.
I was going to reuse the ROMs from the damage SIMM (was mainly around the contacts area) and foolishly assumed that the ROMS from the SIMM were the same as the socketed ROMs on the reloaded board - but alas that is not the case. So the ROMS are the only ICs which are "new" freshly burned (and verified) by my Mini Pro TL866.
So on the reloaded board, I socketed everything that was ...ahem... socketable. The reasoning was that eventually I would do more boards and could use this initial board to test all IC components.
I found the sockets a bit of a bother and cut away the bottoms to solder them on to the board. The bottom of each socket has a non-conductive card of a similar thickness to keep the IC at the correct height when inserted.
I've carefully checked and sounded out the ROMs and FPU to the CPU on my meter and scope.
The CPU, video rom and PALS HAVE all been tested as working on another SE/30 that happened to have all these ICs already socketed.
Does this look like a Video RAM issue?
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Yes they are bridged. I don't think the screen would have shown anything without access to the ROMs?
Or does the screen refresh completely independently from the CPU using the PLA logic and video rom only?
Also there are a few other new components like the 30-pin SIMM sockets and the fuses.
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I did this for my first two boards and it’s a great idea for testing chips, although I’ve damaged a few cosmetically during removal even with a chip puller, so take care with that.
The chips need to be very clean before they’re inserted, so that’s one thing to check - one of them might not be making perfect contact.
I cut away the bases as well, although I found I didn’t need any shims for them to sit at the right height. I think those bases are designed to be removed.
It’s a simasimac. This is the uninitialised contents of VRAM which will display even if there’s no access either to the ROM or Video ROM.
I’ve always wanted to try a build with PLCC ROMs as it’s kind of cool but I need the flexibility of a ROM socket. Did you use the bitswapped images on Bolle’s GitHub? The Reloaded board needs byte-reversed code and this could potentially trip some people up.
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