G4 power mac PCI, cuda / pmu button (s),  what is the button next to the cuda / pmu button for ??

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G4 power mac PCI, cuda / pmu button (s),  what is the button next to the cuda / pmu button for ??

In this photo from Apple on resetting the "cuda" or "pmu", there is the proper button circled for the reset. My question maybe silly, but WHAT is the button just to the right of it for ?? ..... It must be important enough to HAVE a BUTTON ?? ..... shown in this photo.

OK, here it is, just outside the red circle, to the right. It must be Important enough to HAVE a BUTTON, yet I have not seen , or heard of it being mentioned anywhere ??? ..... I have this very machine and I am expierencing some problems with it, and I find myself so tempted and wanting to push it !!, ... But not knowing what it's for has the wheels inside my head spinning (like mad). .... It and other things maybe driving me crazy (ier) !!

ANYONE KNOW WHAT IT'S FOR ????? ............. Thank You, and Have a Nice Day !!, wayne146

Posted on Jul 7, 2011 4:32 AM

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Answer 1

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japamac

Level 7

24,400 points

Jul 7, 2011 5:04 AM in response to wayne146

The circled one is S4, the CUDA button.

S5, next to it (to the right) is a power button:

S5 is used to help drain retained charge from a machine (unplugged) prior to CUDA reset.

If the machine is plugged in, that button will start it.

Old school CUDA reset:

Turn off and unplug machine.
Wait 10 minutes.
Open machine and touch tin around the I/O panel (static discharge).
Press S5 power button ONCE.
Press S4 CUDA button ONCE.
Close machine.
Plug in and start up.

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Answer 2

wayne146 Author

Level 1

60 points

Jul 7, 2011 5:32 AM in response to japamac

japamac, thanks for the fast reply,

I have done the cuda reset with some success, still not working correctly though, machine only responds to power button on the front, not to the k/b button, (it did before) even used another k/b, both known to be good. Since this problem started, cuda reset has been done a few times, with some time intervals between them, battery tested, new battery, etc., etc.

On my screen here, near the top, is a column titled, "more like this", in it is a "green checked" answer that reads; After resetting cuda / pmu, doesn't power up, 400mhz imac (<not my machine, I know) what next" answered by "Spudnuty", IN his reply's he mentions a list called "Symptoms / Cures Tables", related to pmu / cuda problems as I read it. Yet I have not found any such list by doing searches varying how I word it.

Would You know of this list ?, or if it is still available ? ..... I had no luck looking for it, ..... wayne146 ....

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Answer 3

japamac

Level 7

24,400 points

Jul 7, 2011 6:16 AM in response to wayne146

Have a look at the following, starting from page 14:

http://www.scribd.com/doc/55669677/65/Logic-Board-Troubleshooting

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G4 power mac PCI, cuda / pmu button (s),&#160; what is the button next to the cuda / pmu button for ??

G4 power mac PCI, cuda / pmu button (s), what is the button next to the cuda / pmu button for ??