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mAcTX - ATX to Classic Macs


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Just a small update today - it looks like the best value for a discharge resistor is going to be 10k at a minimum. I'll be sticking with 10k because the mAcTX Compact board has a 10k on the 2N3904 and why make your order any more complicated than it has to be?

 

 

 

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  • 2 weeks later...

Maybe it's been a while but we haven't have forgotten you! The PCB for the Macintosh IIc* is finished footprint wise, and I think we've got the components nailed down too. So, onwards with findings:

 

1.) ATX seems to not be ATX 100% of the time. By that I mean we've been thinking @blusnowkitty's IIsi had issues this whole time but that's not the case - it's my ATX PSU I was using. It seems some ATX PSUs are more forgiving to rapid on/off. The other one wouldn't reset right away so the system would shut down right. The new one wasn't happy that there wasn't an immediate drop in the ATX_ON signal and reset right away.

 

The fix was to up the resistor for the /pfw line which now works perfectly. Even better is that change didn't break compatibility with the Quadra 650 - need to test IIcx and IIci later today.

DSC_9233.thumb.jpg.741003509f677c9a25a5cb6a762a97dd.jpg

 

Here it is with those changes in the Quadra 650. Line is still high enough to not mess anything up - works fine!

DSC_9239.thumb.jpg.b2d41682acd40cff19adf09527dc8aa7.jpg

 

 

I've also done some load testing with the final version of the board! Full tilt 33 MHz '040, three 24-bit video cards and a spinning hard drive still keeps it above 5V on the board output - and that's with 1oz poverty copper. 

DSC_9184.thumb.jpg.5bc2bbf01d9f9edcb55adcdf92a9a9e4.jpg

 

 

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We decided that in the name of keeping costs down, it was better for us to ditch the DIP socket entirely and use a surface-mount MAX660. This means that the kit version will ship with a MAX660 already soldered to the board - it's not hard to do SOIC-8s by hand, but it's very annoying. Might be a lot harder if you don't have a nice Hakko like I have. On the flip side, that means we have lots more +5v plane space :D 

 

With that, the mAcTX project is nearing the end of development - we're getting some test boards printed up of the final design in its final colours, getting documentation together, and then we'll be open for pre-orders!

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3 hours ago, trag said:

As long as you're going surface mount, why not switch to a single inverter package?  Five pins I think although one is unused.  It would be even smaller and might cost a bit less.

Simple - I'm not skilled enough yet to do anything smaller than a SOIC-8 :D

 

The other reason is that the MAX660 SOIC-8 part is pretty much the least expensive we can get while not being crazy small to solder. There's one from TI that's a few pennies smaller but it's a tiny 5-pin package. 

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16 hours ago, blusnowkitty said:

Simple - I'm not skilled enough yet to do anything smaller than a SOIC-8 :D

 

The other reason is that the MAX660 SOIC-8 part is pretty much the least expensive we can get while not being crazy small to solder. There's one from TI that's a few pennies smaller but it's a tiny 5-pin package. 

Limitations for assembly is always a good reason.   I designed some SIMMs with four chips on each side, even though there was room for all eight on one side, because four & four left room between them for a soldering pencil...

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  • 2 weeks later...

Final test boards showed up today! Just a couple of minor silkscreen tweaks left to do but otherwise what you see here is going to be the final shipping product. We're also working on finalizing documentation and we plan to have pre-orders live by next week. Until then, here's some pictures!

 

 

IMG_4713.JPG

IMG_4714.JPG

IMG_4715.JPG

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  • 1 month later...

Good news: There has been some work going on behind the scenes! There's currently a power switch/DC input mounting solution for the Mac LC version in the works. First prototype didn't quite have tolerances needed to get the power toggle in, but the 2nd should. It was printed today and should be here Tomorrow or Friday. 

 

The Mac IIc* version is still in the works.

 


image.png.8cace4b2c0a6c543085bf4716af58810.png

 

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Still lovin' this project, guys. Can't believe I missed these updates! The "do you use a Mac" topic blew you off the top page. I searched to get here looking for a dead-on top view of the LC variant or a pic of its PCB layout. I'm working on a visualization project in Illustrator, got anything handy?

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On 4/14/2020 at 12:35 AM, adb9001 said:

I am interested in buying an adapter for IIsi when you are ready to sell/ship. Thank you for creating this useful adapter.

I am also very interested in this project, and I would love to replace the PSU in my IIsi with a modern one. What is the current status of the IIsi board version you are working on?

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On 4/18/2020 at 9:02 AM, Trash80toHP_Mini said:

Any chance you'll be doing a version for the Quadra 630 thru 6500 series?


I could, but I don't have much reason to. I don't think I've ever seen one of those fail. It wouldn't be hard since it's just a repinning of current design, I'd just not see much use.

That, and I only have a Quadra 636. No 6400/6500.

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That bracket is a thing of beauty

 

6XX and 6500 would be the same as I understand it. 6360/6400 require 3.3V for PCI whereas TAM/6500 roll their own 3.3V on the MoBo. PowerCC lore is full of SoftPower and 3.3V bugaboos and a recasing someone was doing here of somethingorother in the series had me curious about your plans. Those machines aren't all that much newer than the IIsi/LCs/605 in terms of PSU's in terms of breathing their last, so I thought to ask.

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