On Mar 15, 3:14*am, "Arfa Daily" wrote:
"William R. Walsh" m
wrote in ...



Hi!

I bought a Philips DVP 642 DVD player in December 2005, and 2 months
shy of 2 years, it failed

This sort of thing is completely inexcusable. I suppose it's brought on by
cost, or at least I hope so, given how many years have gone by since the
electrolytic plague took place. This computer (see the sig) is running on
all of its original electrolytics, as is the Deskpro EN a few places down
and many other devices. The EN runs some of its 'lytics a little bit warm
to
the touch, but it's still going. It runs 24/7.

This machine also spends a large amount of time powered on, and was used
as
a server prior to falling into my possession sometime in 2002.

I tried to save a 16-port SMC ethernet switch after it started acting up.
One of the electrolytics was blown up, but a replacement did not restore
normal operation. My guess is that damage to the other circuitry had taken
place.

So it *can* be done. I suppose the only reason it doesn't always work out
is
due to cost and the odd defective unit.

William

Further circuitry damage can often be a consequence of failing smps
secondary-side electrolytics. If the supply monitors say the 12v rail for
regulation feedback, and the filter cap on that rail goes bad, the resulting
hash and ripple can appear to the sensing circuit as a low output. This
causes the m/s ratio of the chopper drive to open up in an effort to restore
the rail to the correct value. As all the other rails are tightly
magnetically coupled to the bad rail as a consequence of them all sharing
the same transformer core, the end result is that the 3.3v and 5v rails can
go sky-high, causing a trail of catastrophic damage to various LSIs in the
equipment.

Arfa

I've seen this with quite dramatic consequences. 2 years ago a friend
brought me a budget DTT-DVD player which was dead. Opened up,and
several caps had literally exploded, but only one was in the psu. the
others were downstream, on the main/processor pcb. Clearly there had
been some catastrophic voltage rise.

The other week I picked up a DTT set top box. Same thing - lots of
exploded caps, with only the legs still on the pcb. The few remaining
electolytics on the main pcb were bulging.
Needless to say, both these units were promptly scrapped as BER.
The lesson is: when something is acting erratically, don't wait before
changing the caps!
-B