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Quadra 650 ATX/MicroMac Conversion


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Hello, I figured I would start a topic for my custom case/ATX conversion of my Quadra 650! I got the logic board from just.in.time for $5 dollars, in untested condition. I actually found the matching connector for the power connector on Mouser! I ordered that, and I used clip leads for a first test, set up for hard power. I connected a speaker, and applied power. The board chimed, and it booted to the question mark. Yay! The board was good. Then, I connected an external scsi hard drive, which was read and it booted.

Now, I'm going to assemble the proper cable so I don't have to use clip leads. I'll post some pictures of it after it is assembled, and then I will work on the soft power circuit.

 

After I convert it to ATX, I will design a case and cut it on my laser cutter.

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You can actually make an inverter board without needing the resistors. Using a 74HCT04 instead of a 74HC04 will work fine. Here's a very shitty board I whipped up a while ago. It works, but it's on my "Remake this thing prettier" some day list.

 

On the front half I screwed up and soldered a 3 pin connector in instead of the needed 4. 

 

0y4qFi5l.jpg?1

 

On the back side I started trying to make solder bridges instead of using wire (looks cooler) but gave up part way after fighting to make them actually connect. I need more practice with that.

4JhZH9wl.jpg

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You'll need a load resistor to #PS_ON as well to bring that line high when /PFW goes low, otherwise it won't be high enough to flip the inverter back around.

 

I never had any luck with the 74HCT04 and no load resistors. I only ever saw it in-use for an iMac. I'm guessing there are minor differences in how the power control IC changes it's logical voltages; stuff like duration, swing time, etc... Worst case scenario is you can pop open the stock PSU and see how Apple set up their load resistors, which seem to vary between models.

Edited by Floofies
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I don't have the stock PSU, so that isn't an option. Also, it worked fine with just a single 10k resistor before I installed System 7.5.3. Oddly enough, the power button on the back starts up and shuts down the system fine.

Just ran a check, and the PFW line does nothing if I tell it to shut down. Let's try this again..

Edited by IlikeTech
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You'll need a load resistor to #PS_ON as well to bring that line high when /PFW goes low, otherwise it won't be high enough to flip the inverter back around.

 

I never had any luck with the 74HCT04 and no load resistors. I only ever saw it in-use for an iMac. I'm guessing there are minor differences in how the power control IC changes it's logical voltages; stuff like duration, swing time, etc... Worst case scenario is you can pop open the stock PSU and see how Apple set up their load resistors, which seem to vary between models.

 

I'll have to try this on a Q650 board some day. I originally read about this working on a 9600 board and I'm using it on a Powermac 8100 board. Haven't got the right connector for a IIcx-Q650 board to hack up a PSU, been on my to-do list for a while.

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Trash: When I got the board from MacMemories it was labeled as Quadra 650, and I swapped its CPU into an LC 575, putting the 68LC040 from the LC 575 back onto the board. Processor worked fine, but one game I wanted to play required the FPU (Space Cadet Pinball).

 

Nothing implied, I was just curious about these particular whack-doodle boards. They can be so many mac models in so many configurations. ::)

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I just ran Clockometer, and it said that my CPU was running at 25Mhz.  It is a 33 Mhz part. 

I started working on the laser cut case parts.  I have a laser at home so there is no cost in cutting parts.  I will do a test shot on cardboard before I cut with the expensive acrylic.  I also need to pick up a scsi2sd.

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  • 2 months later...

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