UPDATE: after I write this post, I realized that Minihac's post (link below) presents a simpler solution. Did not read it with attention when i was doing my mod.
: Maybe you could try as him suggested, and use the common ground for everything.
3. Reuse the front panel circuit
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I didn't find any good or complete info about how to reuse the front panel. Anyway some info about the panel board's pinout here in tonymac help me a lot.
http://www.tonymacx86.com/powermac-g4/50357-pinout-circuit-g4-sawtooth-switch-cable.html
Fortunately, the sawtooth board appeared to be de simplest of all powermac g4 line.
Here is the pinout scheme, according minihack's post (take a look at his thread. there are pictures too):
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1.S3+ programming switch; Don't use.
2. No connection.
3.S2+ Reset switch.Use for reset switch + if you want
4. No connection.
5. S1 +; Use for Power Switch +
6. No connection.
7. Not useful (part of the apple circuit).
8. COMMON GROUND; Use for Power Switch -
9. Anode 1 (glows LED Green); Use for Power LED +
10. Anode 2 (glows yellow); Don't use.
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In my mod, I planned to use the original flat cable. Maintained the conector to panel board, and cut the cable near the other side.
I wished to connect 3 things: On/Off power switch, Power led and reset.
Started with the obrigatory power switch. So I used Pins 5 and 8. No modification needed in this case, just find the 5 and 8 pin out in the flat cable and did a soldering to a double connector. done!
So I started with the led. The panel has a two color led, and it uses pins 9 and 10 as Anodes and probably the common ground (8) as Catode (not sure). With the new mobo I need a new Catode, as the 8 was used for my power swtich. So I did a little soldering, and put the Catode (the middle led conector) connected in pin 7 (see first image below. the
red wire). Then, my led connects to pins 7,9 and 10. I cut the connection between the led and another pin (see the second image). Not sure if it is really necessary, but appeared to be a good decision.
... and then put a triple connector in the flat cable end, connected the mobo and.. just the green worked...
In fact I think the led would glow orange when the computer is sleeping, but I was wrong. Just the green is working. Maybe someone could help me with that? suggestions?
Anyway the soldering to the pin 7 worked to the green glowing.
Finally, decided to use the reset original pinout
In the third modification I connected the Reset switch using pins 3 and 4. Did a soldering job (the
yellow wire in the picture above). Put a double connector in the end of the flat cable, connected to the motherboard and... the reset switch didn't worked too. Damn! Maybe someone could help me with that too? Suggestions?
Well, my work in the front panel board ended with the on/off switch fine, and the green led working too. No orange sleep led ou reset switch yet. :/
Here, a picture of the soldering work in the flat cable motherboard's end (could be better):
And everything connected in the motherboard (could be better too):