LC575 PowerPC motherboard upgrade options?

[moothefish]

I've actually just done this with a 575 and a Performa 5300 logic board. You basically have to perform the takky mod process on the 575 chassis, and swap the edge connector/wiring harness from the donor machine into the 575. Not a reversible process since you have to cut away (or rather crumble away) various bits of plastic and cut new slots to mount the new edge connector further into the chassis (even then, the board does stick out the back approx 1cm or so). 3.3v mod isn't required depending on the board you use, in my case the system works without it and I don't have any expansion cards that need it.

I haven't yet gotten the speakers or front panel buttons to work since I couldn't find any pinouts/wiring diagrams for the 575 front panel board (different from the CC one), but the audio output on the back at least works for now

This came about because in my years long quest to find a complete working 575, I ended up with two 575 shells with battery-eaten logic boards, and since everyone steals their damn boards for their CCs, i've not been able to find a replacement original board for anything close to a sensible price. Recently I acquired a Performa 5300 with a very tired CRT and a hole in the side of the case, so figured I would try and at least make something from the 3 machines. (would still love to have a working 68k 575 since its one of my favourite macs, so if you have a board you want to get rid of, I can assure you it won't end up in a CC like most others..lol)

 

[Phipli]

I've actually just done this with a 575 and a Performa 5300 logic board. You basically have to perform the takky mod process on the 575 chassis, and swap the edge connector/wiring harness from the donor machine into the 575. Not a reversible process since you have to cut away (or rather crumble away) various bits of plastic and cut new slots to mount the new edge connector further into the chassis (even then, the board does stick out the back approx 1cm or so). 3.3v mod isn't required depending on the board you use, in my case the system works without it and I don't have any expansion cards that need it.

I haven't yet gotten the speakers or front panel buttons to work since I couldn't find any pinouts/wiring diagrams for the 575 front panel board (different from the CC one), but the audio output on the back at least works for now
View attachment 67069View attachment 67070
This came about because in my years long quest to find a complete working 575, I ended up with two 575 shells with battery-eaten logic boards, and since everyone steals their damn boards for their CCs, i've not been able to find a replacement original board for anything close to a sensible price. Recently I acquired a Performa 5300 with a very tired CRT and a hole in the side of the case, so figured I would try and at least make something from the 3 machines. (would still love to have a working 68k 575 since its one of my favourite macs, so if you have a board you want to get rid of, I can assure you it won't end up in a CC like most others..lol)

5300 is a good board for it - it has a 603e and doesn't have PCI, so no 3.3v.

One thing, your last photo, I strongly recommend putting more RAM in the computer and reducing the amount of virtual memory. As set up there will be a BIG speed penalty.

 

[moothefish]

5300 is a good board for it - it has a 603e and doesn't have PCI, so no 3.3v.

One thing, your last photo, I strongly recommend putting more RAM in the computer and reducing the amount of virtual memory. As set up there will be a BIG speed penalty.

That's just a random install from the original HDD in the performa, was just using it for testing/display adjustment. Will be running a fresh OS install without any of that rubbish further down the track. Does explain why its so slow in this install (I also think this HDD is on its last legs, but since its now a performa, I can just stick a newer IDE drive in instead of messing with old SCSI drives)

 

[Phipli]

I also think this HDD is on its last legs,

This again might be just because there is so much virtual memory turned on. Put 32MB RAM on the board and set virtual memory to 1MB or off and you'll see performance improve across the board. Disk and RAM and everything that depends on them (which is pretty much everything!)

 

[Burgertrench]

The Micromac product included an adapter board (soldered onto the new logic board), which converted the edge connector. So what you are talking about is not a simple DIY solution.

I happen to have the Micromac upgrade pictured. It is destined for eBay, as my LC575 fell to pieces, I was moving, the COVID lockdown was on, and some things just had to get thrown out (though the logic board got sold, drives saved, etc).

Micromac’s solution used 5200 boards and their derivatives. The bucket at the rear end was metal. Mine had the better 5260 logic board or some such in there — though I strongly suspect that something like a 6400 board could be made to work by someone with the requisite soldering skills. Alas, that’s not me. One of the interesting things about the adapter board is that it includes a jumper allowing for a selection of machines. The Color Classic is listed.

No good to ask for pics just now, as it is in storage and I am not at home for the next couple of weeks in any case.

I have a 575 with no logic board, and would be very interested in the Micromac board if you have not sold it yet? I was wondering if it would be possible to re-create one with an edge connector to allow for a non destructive upgrade, or at least photograph and document the part since there is little information online about it.

 

[OriginalDan]

strange i wasn't getting email notifications to this thread, well update is: the lc didn't survive the shipping process even before leaving japan :/ I've successfully shipped CCs and other CRTs from japan without issue but yeah i guess that notorious brittle plastic strikes again... currently in email talks to see if i can get the logic board recovered and shipped.
Still keeping an eye out for a local one but they rarely pop up around victoria and when they do they're extortionate prices, might be better off with a more regular power pc build lol.

thanks everyone for the info, Phipli ill keep that 3dfx mod in mind if i ever come across the right combo of gear.

damn moothefish that's a pretty mint mod well done

 

[joshc]

575s shouldn’t be shipped. Same goes for 5200/5300 AIOs. Too fragile.

A beige G3, or B&WG3 or a G4 tower would make a good PPC gaming rig without all the messing around.

 

[OriginalDan]

575s shouldn’t be shipped. Same goes for 5200/5300 AIOs. Too fragile. A beige G3, or B&WG3 or a G4 tower would make a good PPC gaming rig without all the messing around.

yeah i figured maybe with some minor damage i can epoxy and repaint but from the limit photo and description it sounds like it really crumbled.
thanks ill be keeping an eye out for g3/g4s

 

[Phipli]

yeah i figured maybe with some minor damage i can epoxy and repaint but from the limit photo and description it sounds like it really crumbled.
thanks ill be keeping an eye out for g3/g4s

A G4 is probably your best bet. Get a graphite or quicksilver (not a MDD with the reflective mirror front, they can be difficult to boot OS9 in some cases) because they'll run almost any PPC game and are currently one of the cheapest macs. Make sure the one you buy boots, because many have bad PSUs.