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mAcTX - ATX to Classic Macs

davidg5678

Well-known member
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?

 

Compgeke

Well-known member
Update: The 3D printed mount is now working great! Needed some slight modifications for tolerances but now it's working great.

mACTX_Mount_1.jpg

MacTX_Mount_2.jpg

 

Compgeke

Well-known member
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.

 

Trash80toHP_Mini

NIGHT STALKER
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.

 

Compgeke

Well-known member
In an actual update, I've placed an order for a good amount the mAcTX Compact PCBs and those should be here next week. Parts to build 20 already came in and I'll see what I can do from there. The actual bracket for DC input on them has not been finalized - but it's mostly just a modification of the LC one to lop off the toggle mount and increase the pawls to stick out more. The IIcx and related chassis uses thicker plastic than the LC it seems. Of course, when I don't have a 3D printer myself it's a lot of testing and waiting for mail. I should get one. 

Additionally, I finally got around to getting another camera lens and that means better bracket pics for the LC variation! 

DSC_9910-3.jpg

DSC_9913.jpg

 

ktkm

Well-known member
Nice! I’m also very interested. Put me down for two of the IIcx version when it’s ready.

 

Franklinstein

Well-known member
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.
There's a little bit of a difference between the non-PCI 63x/62xx/63xx and the PCI 6360/64xx/65xx series: when viewed from the top with the edge connector toward you, the non-PCI boards have their power pins arranged left-to-right 12v/G/G/G/5v/5v, while the PCI models are 12v/G/G/3v/5v/5v. So you can't just slam a 6500 board into a 62xx even if you're counting on the 6500 board to supply its own 3.3v PCI power because the edge connector's 3.3v line would be connected to ground. It's possible you can cut the offending ground line at the harness so that it's no longer connected and run your 6500 board that way, but I've never tried it; I've always just built a 3.3v VRM into the harness.

I also learned something from Pioneer's MPC series of computers: they all use the same power supply, regardless of whether they're used with the Q630/62xx board or the 6100 board. The difference is that the soft-power models have the standby connector going to the logic board while the hard-power 6100 units don't. If the standby power isn't used, the computer turns on as soon as the rocker switch is turned to ON. If standby power is used, it turns on with the power key/button (and with the rocker switch in the ON position, obviously).

Maybe if an adapter is built for the 610/660/6100 you can just short the PS-ON circuit so that the power supply turns on as soon as the rocker switch is turned to ON (you'll need a switch-equipped power supply of course). One day perhaps you could build a universal mAcTX board that uses interchangeable harnesses and have a jumper that shorts the PS-ON circuit for hard-power Macs or is removed for soft-power models. All of these computers usually have pretty standard voltages, it's just a question of whether or not they're used; the different harnesses would supply or leave blank any lines as necessary. If a weird voltage was required, a resistor or other passive component could be built into the harness.

 

blusnowkitty

Well-known member
Maybe if an adapter is built for the 610/660/6100 you can just short the PS-ON circuit so that the power supply turns on as soon as the rocker switch is turned to ON (you'll need a switch-equipped power supply of course). One day perhaps you could build a universal mAcTX board that uses interchangeable harnesses and have a jumper that shorts the PS-ON circuit for hard-power Macs or is removed for soft-power models. All of these computers usually have pretty standard voltages, it's just a question of whether or not they're used; the different harnesses would supply or leave blank any lines as necessary. If a weird voltage was required, a resistor or other passive component could be built into the harness.
Here's the thing: We already have that implemented in the II Compact board since there are some Macs out there with soft power circuits that have failed. It's an optional part of the board and we won't be shipping wire or a switch to use it, but the option is there with a dedicated header for it so you don't have to go look up an ATX schematic and do some hacking.

We may visit other Macs in the future (I have a Quadra 610 and I'm looking at buying a 6200CD) but for now we're really trying to get the II Compact and LC boards out the door since we've been promising them since last year but the world seems to have conspired against us...

 

Trash80toHP_Mini

NIGHT STALKER
I hear you about getting product out the door. That wasn't fun back in the day when there was no pandemic. Love your work, it's amazing.

There's a little bit of a difference between the non-PCI 63x/62xx/63xx and the PCI 6360/64xx/65xx series: when viewed from the top with the edge connector toward you, the non-PCI boards have their power pins arranged left-to-right 12v/G/G/G/5v/5v, while the PCI models are 12v/G/G/3v/5v/5v. So you can't just slam a 6500 board into a 62xx even if you're counting on the 6500 board to supply its own 3.3v PCI power because the edge connector's 3.3v line would be connected to ground. It's possible you can cut the offending ground line at the harness so that it's no longer connected and run your 6500 board that way, but I've never tried it; I've always just built a 3.3v VRM into the harness.
I've been rethinking the connectors used in the 630 type and PCI type harnesses. Ran across a Molex pin extractor/installer tool this week and remembered it being used to rearrange pins in a G4(?) ATX conversion. Haven't got a PSU handy, so I've been wondering if that power connector series could simply be removed and the wires/pins from the harness removed/rearranged/reinstalled in the connector from an ATX power extension cable?

 

Franklinstein

Well-known member
@blusnowkitty, not trying to be down on your efforts. On the contrary: I applaud them. Great work. Happy to help if I can. I just wanted to add some thoughts should you decide to add support for more models in the future and possibly consolidate to a universal board to reduce costs.

I've been wondering if that power connector series could simply be removed and the wires/pins from the harness removed/rearranged/reinstalled in the connector from an ATX power extension cable?
I just looked and it appears that you can: the offending ground wire has its own connection at the power supply header, so depending on which board you want to use it could be made to go to ground or 3.3v.

I think the reason people with Takky CCs were able to get plug-and-play 6500 board support is because they only have two of the three grounds connected (the CC's analog board only supplies two ground wires, not three). So the third ground wire that would otherwise ground out the 6500's 3.3v supply line is left disconnected, leaving the onboard VRM to supply the 3.3v. I've tried this in my Takky before and while the board does boot, it was always unstable, usually involving disk problems. I added a 3.3v VRM to the harness and the problems went away.

 

blusnowkitty

Well-known member
@blusnowkitty, not trying to be down on your efforts. On the contrary: I applaud them. Great work. Happy to help if I can. I just wanted to add some thoughts should you decide to add support for more models in the future and possibly consolidate to a universal board to reduce costs.
Oh no didn't take it that way at all, we just haven't really gone into the specifics of what else the boards can do... which right now is pretty much just that bypass switch :D

 

Trash80toHP_Mini

NIGHT STALKER
The first time I saw the tool for rearranging Molex pins and that approach to ATX modding was a real eye opener for me. I'll order up the extractor/installer tool before I look at anything else related to my PSU issues for the 6500 MicroTower build. It's amazing, I spent so many years bottom feeding a handful of the 50MHz 6500 boards only to discover that they're a nightmare in terms of compatibility. One of those will definitely be headed toward a maniac inspired MicroTower hack. The 6360 and 6400 boards are now slated for the serious hack builds.

 

blusnowkitty

Well-known member
08e71f907570422690b54cbfeb523bac.jpeg.e7a5a555f55eca5e8e9e1916cc1050ae.jpeg


mAcTX LC is coming.

 

Bunsen

Admin-Witchfinder-General
Is there a definitive single list of all versions of these boards that exist / are planned, and what machines they're compatible with?  Having read through the thread, I'm still unclear on that.

 
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techknight

Well-known member
I know I am super late on this, but, with the IIsi, instead of spinning your wheels with the 7404, you could have used a 7406. :)

 

IlikeTech

Well-known member
Interestingly I think I got an adapter like this to work with my Centris 650 with just a 2N3906 as the only part.  No resistors.  This was quite a while ago though so I may be totally wrong.

 

Compgeke

Well-known member
So here's the rundown since the thread kind of turned into a jumble.

There're two versions currently just about ready to go. Final hardware revisions done and all that stuff. Just working on the other random stuff like documentation rather than hardware. That, and sorting out 3D printed parts.

The first is the mAcTX LC. This one is for the LC 1/2/3/Performa variations/etc. This is the final design and setup for how it works, sans that heatshrink on the motherboard lead. That'll go. 

DSC_9999.jpg

The next is the mAcTX II Compact. This one's for the Macintosh IIsi mainly but also works in the IIcx, IIci, etc, etc. Hardware wise it's done but I don't have the rear mounting bracket stuff finished yet. All the 3D printed tests are bummed off other people since I don't have a 3D printer myself. I've also got 50 PCBs and parts to assemble 20 full boards already here.

macTXIIc.jpg

 
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