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Reverse Engineering the Macintosh SE PCB & Custom Chips for 1:1 reproduction


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20 hours ago, Bolle said:

Any idea how you are going about the I/O shield/frame/mounting tab metal piece?

Desoldering the old one is possible but it's not really an easy task (+ on most of my battery-disaster boards they are heavily rusted)

Did you try if the board holds in place without the mounting tabs holding it?

It doesn't look too complex - if we could free one we could draw it up, get some lasercut / waterjet cut and hand fold them? I don't mind doing the drawing and making some (I could make some aluminium prototypes at home), but I don't have a spare / scrap board to get one from.

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23 hours ago, Bolle said:

Any idea how you are going about the I/O shield/frame/mounting tab metal piece?

Desoldering the old one is possible but it's not really an easy task (+ on most of my battery-disaster boards they are heavily rusted)

Did you try if the board holds in place without the mounting tabs holding it?

 

I cranked up the heat on my schlorp-gun to max, and sunk the nozzle into the solder puddle and pulled the trigger, that got rid of most of what was in the holes, then tidied up with solder wick and an iron with flux, untwisted the twisted bits, then just put some pressure between the board and the frame and used the hot air station on the underside, so the frame is held in only by solder and it just falls out.

 

Bit of a pain but ehhh, now i have the frame out, i could flatten it out, then trace it in something like fusion 360 and send off for it to be stamped out on a sheet so people can bend themselves a new one.

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On 2/24/2021 at 1:09 AM, techknight said:

is the logic board still not booting yet? 

 

No, not yet. I have bodge wires soldered to the logic board in places to look at certain lines - but i've had literally zero motivation to try anything yet - weekends are too precious, really, really sleep deprived at the moment :(

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On 2/24/2021 at 9:26 PM, Kai Robinson said:

 

No, not yet. I have bodge wires soldered to the logic board in places to look at certain lines - but i've had literally zero motivation to try anything yet - weekends are too precious, really, really sleep deprived at the moment :(

Hardcore same, friend; working my third mandatory weekend of overtime in a row. Don't rush perfection.

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On 2/24/2021 at 9:53 AM, Phipli said:

Whats the rush? It hasn't for the last 30 years either :)

 

Oh i dunno, we are 28 pages in, and its a nice clone. so I was just kinda expecting it to work.

 

But, i suppose not. :-)

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20 hours ago, techknight said:

Oh i dunno, we are 28 pages in, and its a nice clone. so I was just kinda expecting it to work.

 

People do things as they have energy, time and health.  My own participation in this has been strongly limited by all three, as has others'.

 

I'm not entirely sure that complaining about the speed with which other people are doing things is particularly helpful or encouraging to people who might be thinking of trying something out.

 

Personally, if I wanted to commit to doing something fast with a given result, I'd go to work.

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Posted (edited)

Illness and lack of time has put the brakes on in some ways, but also a botched board run (my fault) means that i have to stump up another few hundred quid for a run of amended boards...and i already maxed out my CC. Hoping to gain some traction, but it's currently only myself so far that's had a built up board.

@techknight I'm more than happy to send you the board, and the customs needed, if you'd like to have a go at building one up and helping

 to troubleshoot it? :)

 

Edited by Kai Robinson
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21 hours ago, techknight said:

Oh i dunno, we are 28 pages in, and its a nice clone. so I was just kinda expecting it to work.


I think it will, with time. Kai has put a lot of time, effort and money into this so far, so I have no doubt that he'll continue to do that when he can.

Also, bear in mind, a lot of other things have been discussed in those 28 pages that are not absolutely specific to the cloned SE board.

As far as I know, Kai is not operating a business here - so this is a hobby, and as with all hobbies, they sometimes have to take the back seat to other things in life.

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22 hours ago, techknight said:

 

Oh i dunno, we are 28 pages in, and its a nice clone. so I was just kinda expecting it to work.

 

But, i suppose not. :-)

A practical way to help push this project forward would be to chip in a few bucks to Kai to help cover the costs of getting PCBs made! I've done that before.

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19 hours ago, rplacd said:

 

A practical way to help push this project forward would be to chip in a few bucks to Kai to help cover the costs of getting PCBs made! I've done that before.

It's not so much the cost at this point - most of the 'big money' has been spent - it's more the fact we need more 'boots on the ground' testers, that have at least a multimeter or 'scope that can help iron out bugs.

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Yep, I'll echo that, testers, we move at the availability/interest of testers.  That being said, this project is probably overall moving at the pace the community desires.  I mean, I think it'd be nice if we could have some more folks test out the replacement RTC design... I probably would have went about creating the slightly more expensive design alternative #2 earlier.

 

But we work with what we have, and we don't take it too hard if one of the contributors has been spending hobby time making a movie with a cameo appearance of a Macintosh SE in the background, rather than perfecting the design of a replica BBU.

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Kai, you may want to check U6B pins 14 and 15 on your Sprint layout against the SE PCB scan. Specifically, instead of one trace connected to pin 14 and one connected to pin 15, you connected both traces to pin 15, thus bridging the SCSI ATN and ACK lines. On Apple's PCB:

  • one trace goes from U6B pin 14, to J5 pin 38. This is the SCSI ACK line.
  • one trace goes from U6B pin 15, to J5 pin 32. This is the SCSI ATN line.

If you look at the 5380 datasheet (page 3, lower right, "PINOUT") and a SCSI pinout, it should help clear things up. I've attached an image highlighting these pads on your layout (left) and the SE PCB (right).

 

Earlier in this thread, you mentioned your homemade SIMMs had trouble fitting, which reminded me of Steve Chamberlin's great article on custom-thickness PCBs for his SIMMs.

 

I found this thread through the Hackaday article. So glad I saw it.

pcb.jpg

Edited by hackshack
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21 hours ago, hackshack said:

Kai, you may want to check U6B pins 14 and 15 on your Sprint layout against the SE PCB scan. Specifically, instead of one trace connected to pin 14 and one connected to pin 15, you connected both traces to pin 15, thus bridging the SCSI ATN and ACK lines. On Apple's PCB:

  • one trace goes from U6B pin 14, to J5 pin 38. This is the SCSI ACK line.
  • one trace goes from U6B pin 15, to J5 pin 32. This is the SCSI ATN line.

If you look at the 5380 datasheet (page 3, lower right, "PINOUT") and a SCSI pinout, it should help clear things up. I've attached an image highlighting these pads on your layout (left) and the SE PCB (right).

 

Earlier in this thread, you mentioned your homemade SIMMs had trouble fitting, which reminded me of Steve Chamberlin's great article on custom-thickness PCBs for his SIMMs.

 

I found this thread through the Hackaday article. So glad I saw it.

pcb.jpg

 

Hi! Welcome to the forum! 

Excellent, i'll have a look at this in a little while, luckily i've not had a chance to get another set of boards made, either :D

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Thanks to @hackshack - I have implemented 3 fixes, all of them pretty major! I'd like to do another board run at JLC, but this time only 5 boards with ENIG just in case :D

 

However, i have 4 boards leftover, and i want to give them out to people that are going to build them up for testing - so @cheesestraws gets one straight away!

 

Also - i have plenty of 'wall art' now, so if anyone wants one for that purpose, by all means get in touch!

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On 3/4/2021 at 4:23 AM, quorten said:

Yep, I'll echo that, testers, we move at the availability/interest of testers.  That being said, this project is probably overall moving at the pace the community desires.  I mean, I think it'd be nice if we could have some more folks test out the replacement RTC design... I probably would have went about creating the slightly more expensive design alternative #2 earlier.

 

But we work with what we have, and we don't take it too hard if one of the contributors has been spending hobby time making a movie with a cameo appearance of a Macintosh SE in the background, rather than perfecting the design of a replica BBU.


I think this has progressed to the point I’m very interested in it. 
 

What would be needed for testers of this board?  Is there a list of parts we can buy that we can solder onto the board or do we need to transplant from another working SE (or both)?  I’d be very interested in this progressing into SE/30 boards. 
 

I’m willing to offer whatever testing snd build support I can.  

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@Kai Robinson I'm verifying your Sprint layout file right now. The DIR pins of the 74LS245 ICs (pin #1) seems to be not connected to the corresponding CPU signal (R/W) due to the missing short trace in the K1 layer.

This trace does exist in the original PCB though (see the attached picture).

 

Did you already fix it?

Mac SE missing U11F U12F R:W connection.png

Edited by powermax
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At this point - the only component you need from an original SE, is the BBU. We have a new GLU based on a GAL16V8, the ADB i can provide on a PLCC to DIP adapter, and the ROM adapter is also something i have. Basically get hold of a maxell bombed SE and you're on the way :D

I recommend that anyone building one up uses turned pin sockets for new parts, and for harvested customs like the GLU and ADB (assuming you're careful enough to get them out in the first place) use dual wipe sockets, they're a bit more forgiving with slightly wonky legs. 

 

@powermax Yes, @hackshack showed me the exact same thing - i can see why my eyes glossed over it. I'm thinking a confluence of these issues would definitely be enough to throw BERR and keep the processor in reset loop. 

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20 hours ago, Kai Robinson said:

At this point - the only component you need from an original SE, is the BBU. We have a new GLU based on a GAL16V8, the ADB i can provide on a PLCC to DIP adapter, and the ROM adapter is also something i have.

What's about the Sony-fabbed sound chip? How much is known about it?

Edited by powermax
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23 hours ago, maceffects said:

@Kai Robinson I've not forgotten the work on the BBU, I've been super slammed with work and the IIe clear case project.  @ScutBoy I haven't even touched the BBU yet, but I'll be starting work on that in the next few weeks as things slow down.  Right now your board is safely sitting on my workbench in the "to do" section :)

 

@maceffects - Don't worry about it. There's no rush on my end, and if it needs to be scraped down layer by layer to find it's secrets, that's OK.

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