On 12/29/2011 12:28 AM, Jay Hennigan wrote:
On 12/28/11 11:02 AM, Mike wrote:
I was using these for exactly the same reasons stated above. This year,
I have had three seperate instances where the switch had to lose power
(move, re-work pwr arrangements, etc), and all three times the PSU
apparently gave up the ghost and refused to power back up. Nothing
'happened' funny power wise, not zapped or otherwise mistreated in any
way. I think these units were of a vintage vulnerable to the bad
chineese capacitor problem and I think whatever cap in the psu just went
fizzle while it was operating, which would let the units continue
running but once it lost power, would prevent a successful full power on
start up.
This is a very common failure mode with some types of switching power
supplies. It is typically a resistor and not a capacitor. We saw a lot
of it with the power bricks supplied with Fujitsu DSL modems a few years
ago. It's real fun when there's a widespread power outage and customers
all over town are down once power is restored.
In this case with the 2970's, it's definately a capacitor. I don't have
my photos now but it was the same cap all 3 times that bulged out and
made it obvious it was the problem.
These power supplies are commodity items from Chinese manufacturers that
are used in a variety of gear, not just Cisco switches. You can often
Google the part number on the power supply brick itself and find
replacements.
I had that idea too but for the 2970 all I was able to find were branded
replacements costing 3x the cost of the used rps675...
Mike-
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