Spare logic board

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Spare logic board

Postby 24bit » 17 Oct 2011, 19:22

Since I read this thread: http://macintoshgarden.org/forum/projec ... x-360-case
I am considering to do something similar with my Rev.A iMac Bondi blue logic board, instead of let it collect dust on the attic.
As I have no xbox, I am thinking of a stock PC enclosure with psu and front panel connectors.
Can anybody tell me how much drives the IDE controller can manage?
What kind of pATA DVD drive could I make use of?
Usually pATA-100 chips could address two masters and two slaves of course, but I did not find any iMac specs so far.
Last edited by 24bit on 17 Oct 2011, 20:02, edited 1 time in total.
Still running: 7100/80 and iMac Bondi blue with a few SCSI peripherals.
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Re: Spare logic board

Postby PowerPup » 17 Oct 2011, 19:37

The iMac G3 has only one IDE connector on the motherboard, (Primary IDE.) So you can only address one master and slave.
If there was a way to hack a Secondary IDE connector to the motherboard, then you could address two masters and slaves.
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Re: Spare logic board

Postby MacJunky » 18 Oct 2011, 01:01

Check out xlr8yourmac.com for info people have posted on doing this conversion, also try google as well.
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Re: Spare logic board

Postby LCGuy » 18 Oct 2011, 14:11

Slot load iMacs only have one PATA controller, however tray loaders (such as the Bondi) actually have two, trouble is that the controller used for the CD-ROM drive has a smaller 50 pin connector, as opposed to the standard 40 pin connector, the only ways I can think to use the secondary controller would be to either make up a cable from an iMac CD-ROM cable and an IDE cable, or to use a 3.5" -> 2.5" HDD adapter in reverse.
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Re: Spare logic board

Postby mcdermd » 18 Oct 2011, 17:55

The slot load iMacs have a standard-size 50-pin connector to the optical. It supplies power in addition to the normal 40-pin IDE connection. After the connection to the optical interconnect board, the cable is cut to the standard 40-pin to the hard drive. The hard drive gets power from a molex connector to the power supply.

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Re: Spare logic board

Postby Gorgonops » 18 Oct 2011, 20:35

As noted already, the trayload (rev A-D) iMacs have two IDE connectors, but one of them is nonstandard. If you're up for some very picky fabrication you can make a cable that will convert the 50 pin connector the CD-ROM drive hangs off so you can put normal devices on it. (I believe the first 40 pins of the connector are the normal IDE lines, the remaining ten include power and CD Audio.) It *may* be possible to find a 2.5 inch -> 3.5 inch hard drive adapter you could just plug into the first 40 pins, as the pitch of the connector is the same as that of a 2.5 inch hdd, but both of the 2.5 inch IDE adapters I've ever looked at had the ground pins tied together in a way which screwed up trying to use one "backwards".

I'm pretty sure you're not going to be able to play DVDs on a Bondi motherboard. It's just too slow, both the video chipset and the CPU. (With the video being the bigger problem.) I had a loose Bondi motherboard with an ATX power adapter for a while (I was planning to cram it into... something, and just lost interest) and at one point I did wire a full size DVD drive as a slave on the primary IDE channel. With VLC it could play the audio of a DVD just fine, but the video was a roughly two frame per second slideshow. It *might* of been faster if the DVD drive had been hanging on the dedicated secondary IDE channel, but I wouldn't be optimistic about it.

If you really do want to try to put a DVD drive in it on its own channel you *should* be able to use a regular laptop one, as long as you have a spare Bondi CD-ROM drive to steal the 50-pin ribbon cable adapter board from. The board *is* removable and has a standard laptop pATA optical drive connector on it.
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Re: Spare logic board

Postby 24bit » 19 Oct 2011, 15:28

Thanks all, for your kind replies and helpful suggestions!
Quite impressive what already has been done with the oldies. I´ll keep my eyes open for a suitable cheap enclosement, in case my last Bondi´s PAV dies.
Good to know what could be done. I might also plug in a CRT from my MacII for some time, if the need should occur.
The old PC boxes are of such an outstanding uglyness...
There are some affordable working G4s on ebay that might outperform anything I could possibly make out of my remaining parts - for even less money.
I´m not quite ready to decide, time will tell.
Still running: 7100/80 and iMac Bondi blue with a few SCSI peripherals.
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Re: Spare logic board

Postby Gorgonops » 19 Oct 2011, 16:33

I came to the conclusion in 2003 that a Bondi motherboard was just too sluggish and buggy to be worth the effort to recase it, so... unless you *really* specifically want to create a bookend, lunchpail, or abstract sculpture that runs OS 9 "okay" and OS X badly it's really hard to imagine it being worth the effort to recase one today. Not with G4 towers being essentially free. But each to their own.

Honestly the really discouraging thing about the Bondi motherboard was it's such an unusual shape and surprisingly bulky. (Being how it's actually a "board sandwich" with that metal CPU cage on top and that oddball power connector on the bottom.) I test-fitted quite a number of "interesting" small-footprint or slim cases, including an old router, a SUN Microsystems disk box, an old stereo, etc, and it wouldn't really fit in any of them. If I'm going to waste the space needed for a full-size PC case then I want something better than 233Mhz and two USB ports.
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