Redundant power supply problem

Is there a RESET button? This sounds like the power on reset circuit isn't being triggered - maybe the power is coming up too slowly or something like that?

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Does it have fan sensors that lock it out if they don't spin? Or might the boot drive be spinning up too slowly?

What I'm driving at is something (probably mechanical) that's not responding in time.

Is the "power good" signal coming up?

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isn't

like

There is, and pressing it did nothing.

There are a lot of things I didn't try, and once I got it to boot I left it alone. What can I add to the to-try list?

voltages voltage sequence? important? Power-good trying above again with hard drives and cards removed

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All the fans seem to be spinning. It only shows a blank screen, and if the HDD was taking too long then it would at least do the POST.

I haven't tested that. I can put a storage scope on it. Any idea what the timing should be in relation to the voltages coming up?

I want to do a battery of tests next weekend (too sick now or I would have done it this week). I don't want to cycle the power too many times, because I think it got a little harder to make it come up each time I tried.

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On Sun, 27 Mar 2005 05:32:13 GMT, "Tom Del Rosso" put finger to keyboard and composed:

From Intel's "ATX / ATX12V Power Supply Design Guide":

PWR_OK delay (T3): 100 ms < T3 < 500 ms

- Franc Zabkar

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Thanks. Does it say what voltage level T3 is referenced from? I mean 5V must pass a threshold before PWR_OK should be true.

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On Sun, 27 Mar 2005 22:36:55 GMT, "Tom Del Rosso" put finger to keyboard and composed:

The undervoltage thresholds are -5% for all three major rails.

See

"PWR_OK is a ?power good? signal. It should be asserted high by the power supply to indicate that the +12 VDC, +5VDC, and +3.3VDC outputs are above the undervoltage thresholds listed in Section 3.2.1 and that sufficient mains energy is stored by the converter to guarantee continuous power operation within specification for at least the duration specified in Section 3.2.11, ?Voltage Hold-up Time.? Conversely, PWR_OK should be deasserted to a low state when any of the

+12 VDC, +5 VDC, or +3.3 VDC output voltages falls below its undervoltage threshold, or when mains power has been removed for a time sufficiently long such that power supply operation cannot be guaranteed beyond the powerdown warning time."

- Franc Zabkar

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