[c-nsp] 7600 dies a fantastic death - What went wrong?

[Justin M. Streiner]

On Wed, 1 Sep 2010, Sascha Pollok wrote:

> I *think* (read: I might be wrong but) that the PSes also switch off
> and show OUTPUT FAIL when the router is shutdown from the supervisor.
> I have seen this e.g. on a 6509 (what was the difference between the
> 7600 and ... just kidding) that got shutdown from the Sup720
> because there was no high speed fan-tray 2 in the chassis after
> 300 seconds or so. The 6509 made a *click* and was off. PSes showing
> OUTPUT FAIL.

I did have a 6000W AC power supply partially fail in a 6509 a few months 
ago.  The supply was fed by two 208V/20A circuits, and one of the INPUT OK 
LEDs was dimly lit, which suggested that input was receiving lower than 
expected voltage.  I tested both of the circuits that fed that supply and 
both were putting out 208V across the two legs and 120V leg-to-ground, 
exactly as they should.  A "show power" showed that the supply was feeding 
the equivalent of 120V into the chassis after being converted to 42VDC 
that the switch uses internally.  The other supply was feeding the 
expected amount of power into the chassis.

The problem went away when I replaced the supply, so my suspicion was that 
something in the supply between the input receptacle and whatever voltage 
sensor reports back to the backplane cooked itself.

jms