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From: larry moe 'n curly on 14 Mar 2010 17:18
On Mar 13, 7:37 pm, n...(a)given.now (Joe) wrote:
>
> I bought a Philips DVP 642 DVD player in December 2005, and 2 months shy
> of 2 years, it failed - having symptoms of a well-known problem with a
> certain capacitor in the power supply.
>
> Well before the problem occurred, I had come across a description of the
> failure and how to fix it by replacing a particular capacitor on the power
> supply board.
>
> It turns out that the particular capacitor supposedly would likely be
> leaking some electrolyte or be bulging - it was doing neither.
>
> When I opened up the player and left it turned on for a few minutes, that
> particular capacitor became very much hotter than any other capacitor, so
> I replaced it, and the player is still working now, some two years later.
>
> A couple of years ago, I bought a Digital Stream DTX9900 digital to analog
> converter box for my old TV.  Son of a ...  it too failed at about the 22
> month mark.  I opened up the case, and there it was - a bulging capacitor
> on the power supply board.
>
> I replaced that capacitor a couple of weeks ago, and the converter has
> since been working.
>
> Anybody else noticed any coincidences like these?  

I think you caught it early, before it had a chance to build up enough
pressure to leak or bulge. But at www.BadCaps.net, the experts
mention that some caps go bad without ever bulging or leaking,
although I've seen only one like that, in my 33-year-old Japanese TV
that's needed only two caps replaced. It's connected to an RCA
converter box that developed 3-4 bulging caps in less than 23 months.
From: William R. Walsh on 14 Mar 2010 20:53
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
--
Brought to you by an IBM PS/2 9585-0XF, "Defiant"
AMD 486-133/64MB/2GB S/N 23HN457


From: Arfa Daily on 14 Mar 2010 22:14

"William R. Walsh" <newsgroups1(a)idontwantjunqueemail.walshcomptech.com>
wrote in message news:j-WdnVY6usNsGQDWnZ2dnUVZ_uOdnZ2d(a)mchsi.com...
> 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


From: Phil Allison on 14 Mar 2010 22:31

"Arfa Daily"
>
> 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.


** Over-voltage protection is essential for devices with such SMPSs - a
sacrificial zener bridging the regulated voltage will do the job for a
single output supply.

Multiple output supplies need something a bit more complex that monitors a
sum off all the DC outputs and reacts to any significant increase.

Many cheap and some expensive products do not have anything.



...... Phil





From: mm on 15 Mar 2010 01:19
On Sat, 13 Mar 2010 18:37:29 -0800, none(a)given.now (Joe) wrote:

>I bought a Philips DVP 642 DVD player in December 2005, and 2 months shy
>of 2 years, it failed - having symptoms of a well-known problem with a
>certain capacitor in the power supply.

Well, I'm not happy to hear this because I have their DVDR 6765 (or
some 4 digit number beginning with 6) the latest one they've sold and
it's nearing two years of age.

There's only one other model** out there with a hard drive, by another
company. and I hear it has fewer features.

This one could be better too, and they've had time to upgrade the
firmware, which is possible, but haven't done so. (But it still works
pretty easily and records DVDs or 160 hours on the harddrive, and can
copy from one to the other.)

**Mine is made for OTA or cable. Most such things seem to be made for
people with only cable or satellite, but even then I guess there
aren't many models suitable for a given signal supplier.
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