68k Soft/Hard Power and ATX conversions . . .

[Trash80toHP_Mini]

. . . I was wondering if anyone remembers seeing a good howto on hacking the original equipment power switch on the back of a compact or II Series Mac to act like the Power Switch/Power on/reset switch for Rainbow era Macs.

Specifically, I'm, trying to get my IIsi to act exactly like a IIsi wen I flip the power switch on, without needing to hit a momentary switch for it to boot.

Same thing for Compacts and ersatz Compact Hacks.

Seems like it should be a simple circuit.

Getting the P6360/6400 and 6500 Soft Power implementation, would be added to the Generic ATX Conversion LCD discussed here: DOA G4/DA/466 = ATX shenanigans . . .

 

[techknight]

This may be the dumbest question in the world, but i gotta ask it.

Why?

 

[Trash80toHP_Mini]

Well, for starters, if I wire up all the proper ATX lines to the proper voltage lines of a IIsi Power Plug, when I flip the switch to "on," nothing is going to happen. The IIsi isn't going to boot because the ATX PSU isn't going to do squat until it gets a Power On/Reset goose from a momentary switch or the circuit I'm proposing.

An old AT power supply is much easier to hack than ATX for a hard powered Mac. Just turn it on and . . . it turns on! The Mac boots and all is well until you shut down the Mac and it tells you to turn off the main Power Switch.

Things may be a bit more or less complicated for the entirely "Soft Powered" 6xx-6xxx series, dunno . . .

. . . but I figured getting a discussion going on how to do every permutation of ATX PSU hack and having the info readily available here was likely a good idea. :-/

. . . that or it's another ID10T error on my part.

 

[techknight]

oh wait, you mean if you wire up an ATX supply, nothing happens when pressing the keyboard power? If you want to wire up an ATX power supply so that the soft-start functions work normally as if the old original power supply was in place, its not hard at all to cook up a circuit to do this.

the ATX system power supply gives you a PS-ON signal, a PS-GOOD signal, and a 5VSB signal to do just this I have used an ATX power supply AND its soft-start circuitry in other electronic projects, being able to turn on the power supply and check the PS-GOOD signal to make sure the power supply started up correctly.

the PS-ON signal (green wire) gets grounded to enable the power supply to startup. Not exactly sure how the mac does it, have no II series macs at all. You would need to feed back the 5VSB signal into the logic board, when the power button is pressed, it trips a transistor that grounds out the PS-ON, and off she blows.

 

[techknight]

On the other hand, if its a non-soft start mac, that you want to convert into a soft-start mac, you need to build a custom circuit to do this. which is VERY easy with a couple transistors and an 8=pin microcontroller. Sense the powerkey/keyboard interrupt, fire up the power supply and itll boot.

Its the shut-down part that might be tricky. Need to figure out a place in the logic board to tie a signal into for the power-down command. I am not sure exactly how a real soft-start macintosh does this. probably a seperate signal line from the VIA and ROM code thats hooked/called during the shutdown proceedure.

Or... just use a timed interrupt inside the custom circuit micocontroller, that senses the power button pressed for 5 seconds, then shutdown. So when your at the safe to power off screen, press and hold keyboard power, and it shuts off

 

[techknight]

Oh and lastly, if you just want the thing to run hot all the time, just jump the ATX green PS_ON signal to ground. (the less fun way). Nice thing about ATX power supplies, it at least gives you the 5V standby signals, something that some of the mac IIs dont, so you gots to have a batt before it powers on.

 

[Trash80toHP_Mini]

8-o :O . . . which is VERY easy with a couple transistors and an 8=pin microcontroller. xx(

 

[zuiko21]

I'm not much into the microcontroller scene, but I think it would be overkill here. I'm already resarching about this, and in order to power up something from the ADB keyboard, I would use a flip-flop chip instead -- cheap, simple (even with a few more pins ) and no programming required.

So far I had no success on shutting down via software... I already located the relevant VIA port, but that won't change on the SE/30, like it does on the IIx :'( My circuit could, however, shut down a IIx with a hacked (non-soft-power) PSU, but there's little point on that.

Now, for something completely different : With the aforementioned grounding of the PS_ON line on the ATX supply, you can power your IIsi as long as the hard switch (on the PSU) is on; but since both the IIsi and the ATX are soft-power capable, you can keep that feature as intended. The Mac controls power via its PWF line on the PSU connector, which is the opposite of PS_ON -- an inverter is required. There's no need even for an IC, you can do that with a simple transistor. I used a BC547B but any cheap small-signal NPN transistor should do, like the 2N3904 (watch the pinout!): emitter to ground, collector to PS_ON, and the base, thru a 10K (or so) resistor, to PWF on the Mac side.

About the 630/6200 and the like... I experienced the same problem (tried with another board -- same results xx( ) but I think I know what's happening: from the Takky upgrade pages for the ColourClassic, it seems that the ADB power line (S3) is needed in order to power up -- the original PSU has a 6-pin header besides the power connector. But I haven't been able to check this, yet.

 

[Trash80toHP_Mini]

TTL and CMOS, NOW we're talking! :approve:

I'd really like to get things Ironed Out and posted in one thread with links to all past threads in the OP.

Edit: just read your linked post, could your problem be that you're not using a momentary switch? I could be reading it wrong because I'm not much of an electron pusher, but having the Backplane Power Toggle send the Power-ON blip to the ATX supply on my flat fat SE/30 is what I'm trying to do. Flipping the original switch off should shut down all but the standby Power on the ATX PSU.

 

[techknight]

TTL and CMOS is too complex for me. lol. i grew up in the microcontroller world, so thats what I use. I do use TTL and CMOS, but the way my mind thinks is different than most.

its just easy for me to write a 5 line assembler program and zip it on an MCU and perform the same functions as a flip-flop. thats just me. And it would solve the issue on macs like the SE/30 where the power-off line does nothing.

press-hold the power key, MCU recognizes it and kills the power supply.

on the TTL side of things, I guess what one could use is a D-Type latch mechanism with a de-bounce filter. when the D-Flop is toggled on, we could turn the power supply on. Then somehow once the system is on, we charge up an RC Time Constant circuit that must discharge when pressing power before it will allow the D-Flop to toggle off. Then we would work ok for hard-start based macs.

Your right, for an already-soft-start mac to ATX conversion, a simple transistor inverter would work fine.

 

[barana]

Could we use all this to get a non softpower mac/IIGS to power on and off with the reset key using an softstart mac ps?

could we somehow get it to see the reset power switch in software to top it all of

(optional)?

 

[techknight]

rather just use the power key on the keyboard.

 

[barana]

yes so would I,the reset/Power key on the KB is one and the same.

 

[techknight]

Oh, ok. I never referred to the power button as the reset button. Thats why I was confused for a second.

 

[Trash80toHP_Mini]

IIcx, IIci, IIsi, Quadra 700

PIN DEFINITION

1 +12V

2 +5V

3 +5V

4 +5V

5 ground

6 ground

7 ground

8 -12V

9 power good

10 +5V (or power on circuit supply voltage)

 

[barana]

@Trash80toHP_Mini

so how would we wire up a hard power supply say mac classic to work with a adb keyboard reset button press and a soft power supply ? ie how do we adapt you idea from atx ps to soft mac ps ?

 

[Trash80toHP_Mini]

I don't really know enough to have an opinion, suggestion or token bit of information.

Zuiko is more up on this than I am and techknight is one of the real boffins around these here parts of the web.

OOPSIE! I just posted the table above in the wrong thread! :

Check the other thread for what I'm up to lately: Switching Mac PSU's @$$tBits + ATX = ?????

Soft power is an afterthought at this point in my hack . . . which explains why I'm designing a prototyping area into Adapter PCB Alpha.

 

[barana]

I might create a new thread in the hopes ppl will brainstorm there, so i can unhijack ur thread Trash80toHP_Mini

here it is viewtopic.php?f=7&t=17937&start=0

please discuss this idea anyone interested/who has the skill! thx

Now back to ur regularly scheduled projecting...

 

[Trash80toHP_Mini]

I love the discussion you got started in the new thread. Great stuff goin' down! :approve:

Meanwhile, back at the banana ranch:

Here's the third rev. of my 10 Pin Soft-Power Switching adapter PCB . . .

It's still more of a schematic than the final PCB layout. Parts will need to be moved around some to get it all to fit in the real world.

I need to check it against the IIcx series PSUs for electrical and form factor suitability.

I've retained the fuses for the PSU

I've retained the IIsi's tuschie connector interface, but I may need to lose the header connector and hardwire it to the PCB to get it to fit.

The ten wire pads from the power connector and matching wires from the PSU look like stitching. I'll need to move them forward.

The relay will need to be moved for clearance when I get to the nitty gritty of mating the f2f PCBs IRL.

The power plug is backwards for clarity, the wires go to the adapter and the plug goes to the PSU.

I still need to get the soft power part straight in my head and onto the PCB/schematic and could use some help there.

It's getting somewhere! :b&w: