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Jaek_3

Takky power supply mod. Help please!

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Hello all, I recently acquired a Macintosh color classic and like a lot of people out there the 16 mhz CPU drove me up the wall. So I took it upon myself to Takky-mod it to try and wring out some better performance, and I was completely successful!

 

I slotted in a Macintosh Performa 630CD motherboard whose harness I used for the project and it worked like a champ. While 33 mhz is certainly better than 16, after a while it started feeling sluggish too. So I got my hands on a Power Macintosh 5500 motherboard and tried it out.

 

The Mac sound plays when I turn it on, but it's almost like the high-voltage is having trouble engaging on the CRT because I can hear it try firing up several times before finally turning on, sometimes that doesn't even happen and the monitor stays off. When the screen does finally glow to life, the picture has a lot of noise and the computer will lock up after no more than 30 seconds.

 

All this sounds to me like a power supply issue, something I read may require modification for this board. powercc.org, the site I followed to modify my CC, says my 5500 series board may require a 3.3V regulator and additional PSU mods I haven't performed. Now I'm not an electrical engineer, so I'll fully profess ignorance on the subject, but I'm a bit confused about how to proceed. I'm tripped up at the bit where the PSU in the diagram connects to the relay, and most everything after that point. 

 

Where do I connect the FG, N, and L lines going out from the new power supply and relay?

Where do I connect the N line from the new power supply into the relay, and where do I attach the second red wire going out from the relay?

 

Which leads are for what on the relay? Where do I attach the yellow and black wires going to 12V from fan terminals, and what value diode do I use? How do I tell which fan terminal on the analog board is for the yellow wire or the black one?

I would appreciate any help anyone can offer, and rest assured I won't be attempting this modification unless I know 100% what I'm doing. Everything works fine with a 5200 board also.

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Edited by Jaek_3

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