[rescue] SGI Challenge L Power

Francois Dion fdion at atriumwindows.com
Wed Jun 2 10:12:07 CDT 2004

Sheldon T. Hall wrote:

>Francois Dion says ...
>>Getting closer. In fact it's a good thing I had this small victory last
>>night. Before I looked at the crimson again, I had decided I'd be
>>playing with the Challenge L and altough the power supply AC good led is
>>on, when I turn the key, nothing happens :O Argh. So now I have to track
>>down yet another problem.
>Well, at last.  Something SGI I can _talk_ about, instead of _ask_ about.
>On my Challenge L, the switch in the back (the circuit breaker) is funky.
>It feels a bit limp when you move it; it doesn't have the firm internal
>"snap" you'd expect.  If you just move it from "Off" to "On", it doesn't
>really go on.  You have to snap it over fairly quickly and forcefully.  If
>you do that when the machine's plugged in, the power-supply fans come on, no
>matter the keyswitch position.  If the PS fans are on, and you'll hear 'em
>if they are, the key switch will do something.  Otherwise it won't.

As you might remember I had gotten a -12V overvoltage a few weeks back. 
Eventually it resume normal operation and then I powered it off for 
about 2 weeks.

You had replied:
>Great! Of course, the reason for the original error is still unknown....

So something was wrong it seems. How it works right now:

Flick the power to "on", comes on ok, power supply fans are on, AC Good led is on (amber). Turn the key to on, and nothing... The LED display backlight doesn't even come on. Nor do the two leds above the SC come on...

Looking at:

Ah! It states:
2.2.1 System Controller and OLSs


Each OLS also has a green and amber LED. The amder LED lights to indicate that the AC input voltage level is within acceptable levels. The green LED lights to indicate that the DC output voltage levels are within acceptable levels. Both LEDs should remain lit during normal system operation.

And of course, the green LED is off. I wasn't sure if that was dependant on the keyswitch or not, but from this it is clear it is self-contained. The key only interrupts power from the 48V output of the PS to the backplane. So I guess I'll be looking at the power supply (Cherokee). Unless somebody has a spare. Man, Octane PS are a dime a dozen, but I bet it's going to be hard to find a PS for the Challenge.


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