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


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How much heat will this circuit generate? I'm assuming not very much at all.
If I'm not mistaken, power dissipation should be around 1 mW -- won't generate any noticeable heat 8-)
It'd be nice to skip the custom PCB . . . and do this conversion with wires inside the equivalent of an epoxy encased dongle
Good idea! I believe a PCB/Protoboard, no matter how small, would be overkill for such a simple circuit.

 

Maybe this inverter could be installed inside the ATX PSU, alhough it no longer would be compatible with regular PCs...

So if I put a 10 Kohm resistor, I can get soft-power back?
No, it's the transistor the one which does the required signal inversion -- the resistor is only to avoid overloading the transistor.

 

As mentioned earlier, the particular model isn't critical -- the cheapest one you could find is likely to be perfectly valid for switching a low current, 5 V signal "slowly". BC547B is an European reference, but you should be able to get a similar 2N3904 very cheaply. If you have, say, a 2N2222 at hand, it would work fine too -- if a bit overkill for the task!

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It'd be nice to skip the custom PCB . . . and do this conversion with wires inside the equivalent of an epoxy encased dongle
Good idea! I believe a PCB/Protoboard, no matter how small, would be overkill for such a simple circuit.

I like the ProtoPCBpiece notion because it's much easier to see the circuit, for folks like myself, and to do it correctly the first time and every time. It's also easy to pre-form the epoxy putty casing for the dongle so it will have an open top and raised boxes (standoffs) to drill and tap for PCB mounting bolts and a cover plate. For those who don't do tapping, substitute drilled holes and screws. For those who don't need the PCB model for visualization/fabrication, they can do it in wiring in the same accessible epoxy putty dongle.

 

I like the KISS principle when it comes to this stuff. Simple for electronics/wiring types is different than Simple/Foolproof for non-electron pushers.

 

I like the plumbing metaphor, I do electron pipe work, so the piping needs to be elegantly done, (accessible so you don't need to punch a hole in the drywall to get at the leaky parts years later) strapped properly to the framing of the house, grounded and vented! [;)]]'>

 

Neanderthal Luddites don't do schematics. :I

 

@ olePigeon: It's ALWAYS good to have a hard cutoff switch, external to the casing. That's code for Electrical Signs wherever codes make sense. If you're doing the KVM thing, a switching power port for a Monitor isn't necessary, but it is nice for a dedicated peripheral or eight. [;)]]'>

 

Rehash of an earlier notion:

 

It might be a good idea to come up with a version of the universal PCB after all. It'd be great to have one single ATX PSU with pads to solder wires/connectors for every conceivable Mac that might need testing. A temporary PSU for use during a hack, or for out of case testing might be another good use for such a PCB/PSU. My SuperIIsi™ project, with the Quadra 700 PSU perched just a tad precariously atop the IIsi PSU's empty metal chassis, would be a prime example.

 

For any given single Mac application, all one need do would be to create and implement that portion of the PCB. HRMMM????? :?:

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If I understand your idea correctly, that Universal PSU-Adapter PCB shouldn't be difficult at all... just take my previous schematic (for the IIsi) and connect the lines in parallel for each Mac-side connector. Some lines from the ATX PSU (e.g. the +3.3V rail, unused and thus not shown in the schematic) would go for certain Mac models only (like the 7600 etc).

 

You don't even need to put multiple transistors for soft power... just connect the /PFW lines (Mac side) together to the resistor, like the only one in my schematic. For those Macs without soft-power (LC, compacts...) a simple switch between the +5VSB line (purple cable) and /PFW would do a "force on" mode.

 

There's another thread somewhere here :?: explaining how to adapt the compact's video output to an old EGA monitor, which would be interesting for testing compact mobos alone ;-)Perhaps a 12" RGB could accept the compact's output (nearly 10% slower hsync freq.) but don't take my word for it! :disapprove:

 

Not sure if some "modern" Macs (G4?) would need extra voltages not available from the ATX PSU, though.

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Great idea about the EGA twist for compacts, we might add the PCB area for a side of PS/2 KBD/Mouse to go with your V and my PSU. I linked to a MicroController schematic for conversion of both in one of the threads. [;)]]'>

 

We can show all these OSX-on-Core kiddies what a REAL Hackintosh is all about! :approve:

 

jruschme knows all about ATX->Gx conversions, As I understand it, that would only need to be separate section with a straight pin<->pin instead of the usual wire<->wire splice/shrinkwrap deal that gives me the heebeejeebies. I like bolting conversion boards up to something solid, that's my simple notion of strain relief. Clearly labeled connections on the PCB would give me the warm-n-fuzzies instead of the usual crash-n burn anxiety on the first fire-up!

 

< . . . HEH! :beige: Wonders just how difficult it could possibly be to do Compact Video to 60Hz VGA conversion, TTL was a snap back in the day. }:) . . . >

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. . . on second thought, belay that last, it's a bit over the top, go figure. ;) To get a quick board layout, skip everything but the PSU conversions for now. For a second rev. I'd like to get suggestions for MicroControllers that the boffins here prefer to work with and just add a prototyping area with the SMT/breakout pads for a couple of them with thru-hole I/O and prototyping section for a PS2->128k Series peripheral converter. Suggestions? I think the initial ATX Converter production board would have plenty of room for that and it'll help speed up the process of getting that up and project up and running. The video portion of the Genuine Hackintosh™ board will have to wait for a later rev. of the Universal ATX->Mac Converter PCB.

 

I'm not familiar with the PCB blanks used for a Power Supply. They all appear to be a single sided copper clad substrate and I'll hazard a guess that the copper thickness is considerably different. You're our resident expert on that subject, ojfd, is this true? If so, can I get a similar thickness/conductive capacity for a homebrew PCB by etching the layout double sided on standard D/S Copper Clad FRP from the likes of CrapShack? I'll also guess that thicker, brownish PSU PCB material is more heat resistant and that there's no solder mask because of the heat considerations. Are these boards clear coated with something to prevent oxidation of the copper? I don't remember seeing green on any (working) PSU PCB.

 

BTW, this thread has been linked to, as well as several others, in The ATX -> Mac Gazette AKA: ATX LinksProject™ thread.

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My local shop only had 2N2222 in stock, and not the other two. Fortunately they're only 10 cents. :) A little round metal can with three wires. Should there be markings on which wire is the base, collector, or emitter? I've never worked with transistors, and didn't know what a base, collector, or emitter was until I looked it up on Wikipedia. :p

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It would be in your best interest to read a datasheet. I say "a" datasheet as active components (2n2222, 2n****, TIP120, LM555, etc) sometimes come in different sizes, or packages by different manufacturers. Most of the time these different packages share conventions such as operating envelopes and pin arrangements. Its important to ensure you are looking at the datasheet referring to the package you have. With that in mind, there should be a small metal tab somewhere on the circumference on the cylindrical enclosure. Using this tab as reference you can check the linked datasheet to determine which leads are which.

 

:beige:

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Strange... Please double-check all connections. You did remove the jumper previously used for firing up the PSU, right? Click here for the IIci's PSU pinout -- it's the same as the IIvx, Q800 etc.

 

Also, make sure that the metallic enclosure of the transistor isn't touching any other contact -- some models have the enclosure connected to the collector. If it's in contact with Ground, will likely show the symptom you describe ("always on"). Ditto if the power button on the IIci is at the "locked" position...

 

If all of the above fails, you may try to disconnect the end of the 10K resistor from the /PFW line, and connect it temporarily to GND -- PSU should stay OFF all the time. And if you connect that resistor to the violet cable, PSU should go ON -- as long as the hard power switch you installed is ON, of course ;)

 

@Trash80toHP_Mini: I haven't though about the PS/2 translating microcontroller because it's a bit beyond my capabilities... and all my compacts use ADB anyway. The problem is not the schematic, but programming it 8-o

 

The compact's video is 60 Hz vertical too... Level switching between TTL and VGA is certainly the easy part here, but the horizontal frequency is 22.254 kHz, way below most multi-sync monitors would accept -- they usually go from about 31 kHz and up, covering at least basic 640x480 VGA (31.5 kHz).

 

However, back in the day there was at least one monitor capable of displaying these frequencies and some "modern" video modes: the NEC MultiSync 3D, if memory serves, accepted 15-38 kHz -- from CGA to early "super"-VGA, with things like EGA or even Macintosh 13" (67 Hz) in the middle. But they seem very hard to get now :'(

 

Anyway, if modern technology is allowed ;) there are nowadays some relatively cheap scan converters which take a CGA or EGA signal and output a regular VGA one -- basically they digitize the input signal into some sort of VRAM, which in turn is displayed at VGA rate. Not sure, though, if they'll accept the slight difference on horizontal frequency from EGA (the closest one). According to this page, the "official" range is 23.5-25.5 kHz, thus unsuitable for compacts (but OK for 12" RGB). Maybe with some tweaking...

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I was thinking that tt or or one of the other microcontroller generation of hackers might have suggestions . . .

. . . if you build it . . . the ProtoPCB . . . they will come. [:o)]]'>

 

Besides, the schematic and source code are BSD licensed and available from the creator of the 24th Anniversary Macintosh

 

2190085878_0925a3e68e_o.png

To this TTL generation electron plumber, the inverse function of that board ought to be a doable project for one of the gang. Having the 128k/Plus/MicroMac_68030 sitting on the desk with KVM hooked up to the switch, sharing the wireless KBD and Mouse of my main workstation 'puters has been on the long-term wish list for a while now . . .

. . . bonus points for adding ADB output to that board! }:)

 

Like I said, Compact video adaptation is a long way off. Modern technology is pretty much all we're talking about for anything but the PSU Conversions. But the scan conversion route is something I didn't think about when I posted: UNDERClocking a Video Card??????

 

< tangent mode >

 

Just re-read that thread and realized that I've got to buy the crystal can you suggested for that RCPII/IIsi VidCard. THX! I also need to finish noodling out the spreadsheet for calculating the different timings for the SuperMac Spectrum/24 resolution hacking project . . . more crystals . . .

. . . now where did that thread get to . . . :?:

Does anyone have a link to the video timings for the VGA inputs on 480p, 720p and/or 1080p? I came up w/zilch the times I searched. :-/

 

< /tangent mode >

 

Meanwhile, I did a rough listing of the hacks near completion/in progress/planning/parts acquisition stages . . . came up with approx. fourteen involving desktops-n-towers, four of those are stalled by, or patiently awaiting, ATX conversions. The DOA DA needs one too . . .

. . . so many hacks . . . so little time . . . :-/

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Strange... Please double-check all connections. You did remove the jumper previously used for firing up the PSU, right?

 

Jumper? I haven't removed any jumpers from the ATX PSU. I must have missed that step. Not even sure where to look.

 

Also, make sure that the metallic enclosure of the transistor isn't touching any other contact -- some models have the enclosure connected to the collector. If it's in contact with Ground, will likely show the symptom you describe ("always on"). Ditto if the power button on the IIci is at the "locked" position...

 

I covered it in kapton tape. Shouldn't be touching anything.

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