Building my own 68k Performa / LC / Color Classic Test Bench

[JDW]

Hrmmm? Has that database been updated with the info @techknight posted about doing 640x480 on the CC "the right way?" IIRC he said he'd do so, but never saw him post on how to do the same with the 12" RGB for LC.

He may not have had time, or maybe he decided against it due to issues presented by "the CORRECT way" method (i.e., "Apple prototype" method) mentioned in his 68kMLA thread. "What issues," you ask? Please read all of the posts by dkjones96 on page 7 of the thread, starting here:

Color Classic VGA Mod. the CORRECT way

Long-term project is an attempt at cramming a DOS-compatible board from a Performa 630 into a Mystic '040. I know it's missing the video port on the motherboard, but... I feel like there's a way this can be done without actually doing a full Takky mod. Everything else is there... it just feels...

68kmla.org

As you can see, he later removed the "the CORRECT way" mod and implemented a more traditional VGA mod.

I mention all 3 methods in my CC VGA Mod video.

I still have the low voltage mod installed, but I've been considering doing the high-voltage mod so I can use the stock CC motherboard again. Why? For testing. Also, someone sent me a damaged LC520, and I salvaged the motherboard from it but can't use it because I have the low-voltage VGA mod installed. The Hi-voltage mod would enable me to use that LC520 motherboard too.

 

[Trash80toG4]

Thanks, that's a very helpful answer in the negative. I'll check the discussion out and your video as well.

I've wondered about that for quite some time, but I've never had much interest in the CC. When it was covergirl'd on one of the Mac mags I thought it was hideous and definitely not a compact. Be that as it may, the Takky shenanigans have been fascinating.

Am I correct in thinking that the harness bars of all drawer Macs have the same physical connections in terms of dimensions of the mounting ears?

 

[This Does Not Compute]

Am I correct in thinking that the harness bars of all drawer Macs have the same physical connections in terms of dimensions of the mounting ears?

IIRC the motherboard edge-connector harness is the same dimensions regardless of Mac model, from the CC all the way up to the 6500. The depth of the motherboards changed with the 580/630 and onwards (which is why the Takky mod requires chassis surgery, to move the harness closer to the front of the computer).

 

[Trash80toG4]

Thanks for the confirmation. Have plans in place to knock together a test frame with easy access to both sides of drawer/harness boards.

 

[craig.sacco]

HI mate,

I was wondering how far you got to for resolving your sound issue.

I have a similar issue with a 580CD with an irreparable CRT. I decided to strip it back by removing the covers, CRT and logic board, and leaving behind the chassis. I got the system to boot (sans video) by jerry-rigging an ATX power supply with the 14-pin power connector left behind with the removal of the analog board. The end goal is to create a custom "Hackintosh 580CD" chassis with USB keyboard/mouse, VGA and BT audio input/output.

Like you, sound was not working through the headphone jack on the logic board. The logic board is very different to the 575 and is more like the Q630, but I have not been able to find a schematic for this board. The closest I've been able to find that shares the same edge connector is the Performa 6500 and it has similar peripheral hardware to the Q630.

My board requires a -12V source in order to operate the DAC chip (for audio) as well as the modem and printer ports. I was able to get sound working by plugging the blue -12V wire of the ATX to the S1 pin of the edge connector (via the analog board connector).

You may have to do something similar with your setup - using the 575 schematic as a reference, a -5V source needs to be provided on the A1 pin on the edge connector. This can be achieved by using a 7905 regulator between the -12V supply from the ATX PSU and the edge connector pin.

Hope this helps