Electrolytics blow after 1 hr

On 2/24/2011 11:44 AM, Jeff Liebermann wrote:
Only once? I think I've probably done it maybe 10 or more times in my
life. Sometimes, nothing happens. Other times, I spray smoldering
oily confetti all over the shop.
Click to expand...
One of my first "I did this" projects was a small line powered
phonograph amplifier built from the RCA Tube Manual book.

It's pretty impressive when you put the voltage doubler caps
in backwards.

Lesson learned, "Electrolytic capacitors are fussy about polarity."

Or course later on, this came in hand when we used to shove a
250 uF 150 V "little beaver" into the end of a line cord and
leave it in the trash can next to another tech's bench. Wait
until they're deep in the middle of something and plug the cord
in.

Great hilarity ensued.

Jeff
The other other one.
 
On Wed, 23 Feb 2011 16:42:44 -0800, Jeff Liebermann wrote:

Another day in bad caps hell. I fish a Dell GX520 out of the pile at
the local recycler and proceed to try and raise the dead. I've done
this many times with good success, but not this time. Upon initial
inspection, I find the usual bulging electrolytic caps. There were 4
identical caps, 2200uF 6.3VDC 105C. I replace them with 2200uF 10VDC
105C caps (Panasonic ECA-1AHG222). Note the increase in working
voltage. These are brand new caps from Digikey. I run the unit
overnight and find that two of the caps now have bulging tops.

Assuming that I may have had some marginal caps in the bag (unlikely but
worth testing), I replace the two that bulged with 2200uF 10v 85C caps
(Panasonic ECA-1AM222) also from Digikey. This is somewhat of a
downgrade, but should work. I also replace the power supply, for no
better reason than I had a spare.

Same problem as before. The two caps blew their tops within a few
hours, leaking caustic goo.
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg> The two large
black caps in the foreground are the surviving 105C caps, while the blue
caps in the background, are the bulging 85C caps.

Using my finger and a thermocouple thermometer, I determined that the
bulging caps are not getting warm or at least are not any warmer than
other nearby components.

I've replace literally hundreds of caps but I've never seen this before.
It really makes me wonder if the bad caps problem might be caused by
something other than defective caps and/or marginal capacitor voltage
ratings.

Duz anyone have a clue as to what is causing this problem? I haven't
had time to probe the board for power supply bus noise or excessive
current quite yet. What I could use is some speculation as to the
probable culprit.
Click to expand...
What makes a cap pop? Heat. Voltage/current surges. Figure it out.



--
Live Fast, Die Young and Leave a Pretty Corpse
 
On Wed, 23 Feb 2011 19:41:13 -0800, Jeff Liebermann wrote:

On Thu, 24 Feb 2011 12:44:58 +1100, "Phil Allison" <phil_a@tpg.com.au
wrote:

"Jeff Liebermann"

http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

The two large black caps in the foreground are the surviving 105C
caps, while the blue caps in the background, are the bulging 85C caps.

** Errr - I hate to tell you this pal ........

but the pic shows all 4 caps installed with reverse polarity.

A smaller cap ( C310) is clearly installed correctly and so are all the
others I can see.

The markings on the PCB are a bit unusual with the white triangle
indicating positive.

.... Phil

AAAAAAARGH! I can't believe I did that. I usually assume that the silk
screened marker was matches the negative stripe on the electrolytics.
Very embarrassing.

Thanks for catching my mistake (as I crawl back into my hole and sulk).
Click to expand...
Lol not the first time that's happened.



--
Live Fast, Die Young and Leave a Pretty Corpse
 
Phil Allison Inscribed thus:

"Jeff Liebermann"

http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

The two large black caps in the foreground are the surviving 105C
caps, while the blue caps in the background, are the bulging 85C
caps.


** Errr - I hate to tell you this pal ........

but the pic shows all 4 caps installed with reverse polarity.

A smaller cap ( C310) is clearly installed correctly and so are all
the others I can see.

The markings on the PCB are a bit unusual with the white triangle
indicating positive.



.... Phil
Click to expand...
Good catch Phil :)

--
Best Regards:
Baron.
 
Jeff Liebermann Inscribed thus:

On Thu, 24 Feb 2011 12:44:58 +1100, "Phil Allison" <phil_a@tpg.com.au
wrote:

"Jeff Liebermann"

http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

The two large black caps in the foreground are the surviving 105C
caps, while the blue caps in the background, are the bulging 85C
caps.

** Errr - I hate to tell you this pal ........

but the pic shows all 4 caps installed with reverse polarity.

A smaller cap ( C310) is clearly installed correctly and so are all
the others I can see.

The markings on the PCB are a bit unusual with the white triangle
indicating positive.

.... Phil

AAAAAAARGH! I can't believe I did that. I usually assume that the
silk screened marker was matches the negative stripe on the
electrolytics. Very embarrassing.

Thanks for catching my mistake (as I crawl back into my hole and
sulk).
Click to expand...
I wouldn't beat yourself up about it... I'll bet we have all made some
mistakes in our time. :)

--
Best Regards:
Baron.
 
On Thu, 24 Feb 2011 21:55:33 +0000, Baron wrote:

Jeff Liebermann Inscribed thus:

On Thu, 24 Feb 2011 12:44:58 +1100, "Phil Allison" <phil_a@tpg.com.au
wrote:

"Jeff Liebermann"

http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

The two large black caps in the foreground are the surviving 105C
caps, while the blue caps in the background, are the bulging 85C
caps.

** Errr - I hate to tell you this pal ........

but the pic shows all 4 caps installed with reverse polarity.

A smaller cap ( C310) is clearly installed correctly and so are all the
others I can see.

The markings on the PCB are a bit unusual with the white triangle
indicating positive.

.... Phil

AAAAAAARGH! I can't believe I did that. I usually assume that the silk
screened marker was matches the negative stripe on the electrolytics.
Very embarrassing.

Thanks for catching my mistake (as I crawl back into my hole and sulk).


I wouldn't beat yourself up about it... I'll bet we have all made some
mistakes in our time. :)
Click to expand...
I once was trying to remove a photographer's external slave flash
powerpack from it's case using two hemostats. I happened to clamp on the
plus and minus output. I think it was 900 volts dc and had several large
electrolytics about 3/4 the size of a soda can. Residual voltage caused
my arms to fly outward and I stabbed a friend in the shoulder with one
pair or the hemostats.



--
Live Fast, Die Young and Leave a Pretty Corpse
 
"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:rfkbm6hkov35ue2vbdnn8c1im1bju99vk4@4ax.com...
On Thu, 24 Feb 2011 12:44:58 +1100, "Phil Allison" <phil_a@tpg.com.au
wrote:

"Jeff Liebermann"

http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

The two large black caps in the foreground are the surviving 105C
caps, while the blue caps in the background, are the bulging 85C caps.

** Errr - I hate to tell you this pal ........

but the pic shows all 4 caps installed with reverse polarity.

A smaller cap ( C310) is clearly installed correctly and so are all the
others I can see.

The markings on the PCB are a bit unusual with the white triangle
indicating
positive.

.... Phil

AAAAAAARGH! I can't believe I did that. I usually assume that the
silk screened marker was matches the negative stripe on the
electrolytics. Very embarrassing.

Thanks for catching my mistake (as I crawl back into my hole and
sulk).


--
# Jeff Liebermann
Click to expand...
Ah, but we've all been there Jeff, we've all been there ... :)

Arfa
 
In article <6v4dm65joh74tuhl8h649j3cb8hg7l9lb6@4ax.com>, Jeff Liebermann
<jeffl@cruzio.com> writes

Nicely done. I vaguely recall cutting across a hot zip cord while
plugged in, and destroying a pair of borrowed pliers.
Click to expand...
I did exactly that a few weeks ago in a moment of inattention.
Fortunately, because we have a decent electrical wiring code here in the
UK, all that happened was that the 3A fuse in the plug blew.

Over that side of the pond, the only protection you have is a 16A or 32A
breaker in the cabinet, which explains the destroyed pliers.

--
Mike Tomlinson
 
In article <Q8asoEBHR4ZNFwnQ@jasper.org.uk>,
Mike Tomlinson <mike@jasper.org.uk> wrote:

Over that side of the pond, the only protection you have is a 16A or 32A
breaker in the cabinet
Click to expand...
I wonder how many sides the pond has. The U.S. has no 16 or 32 amp
breakers.
 
In article <prestwhich-99F154.04413325022011@news.eternal-
september.org>, Smitty Two <prestwhich@earthlink.net> writes

I wonder how many sides the pond has. The U.S. has no 16 or 32 amp
breakers.
Click to expand...
Whatever.

The point still applies. You only have the cabinet breaker to protect
the circuit, here we have individual fuses per plug in addition to
whatever fuse(s) the connected equipment has.

--
Mike Tomlinson
 
On Fri, 25 Feb 2011 10:28:23 +0000, Mike Tomlinson
<mike@jasper.org.uk> wrote:

In article <6v4dm65joh74tuhl8h649j3cb8hg7l9lb6@4ax.com>, Jeff Liebermann
jeffl@cruzio.com> writes

Nicely done. I vaguely recall cutting across a hot zip cord while
plugged in, and destroying a pair of borrowed pliers.

I did exactly that a few weeks ago in a moment of inattention.
Fortunately, because we have a decent electrical wiring code here in the
UK, all that happened was that the 3A fuse in the plug blew.

Over that side of the pond, the only protection you have is a 16A or 32A
breaker in the cabinet, which explains the destroyed pliers.
Click to expand...
In the USA, we only make big mistakes, so oversized breakers are
totally functional. We also use it as a Darwinian filter, as sloppy
techs usually don't survive very long. After 150 years of natural
selection, we have bred a race of very careful technicians.

Circuit breakers here are in increments of 5A up to about 25A for
domestic service. None of my breakers are labeled, so if I need to
know which breaker controls which circuit, I just plug a short into
the wall socket, and check which breaker has tripped. Very handy.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
Mike Tomlinson wrote:
In article <6v4dm65joh74tuhl8h649j3cb8hg7l9lb6@4ax.com>, Jeff Liebermann
jeffl@cruzio.com> writes

Nicely done. I vaguely recall cutting across a hot zip cord while
plugged in, and destroying a pair of borrowed pliers.

I did exactly that a few weeks ago in a moment of inattention.
Fortunately, because we have a decent electrical wiring code here in the
UK, all that happened was that the 3A fuse in the plug blew.

Over that side of the pond, the only protection you have is a 16A or 32A
breaker in the cabinet, which explains the destroyed pliers.
Click to expand...

All that proves is that you live in a 'nanny state'.


--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.
 
Meat Plow Inscribed thus:

I once was trying to remove a photographer's external slave flash
powerpack from it's case using two hemostats. I happened to clamp on
the plus and minus output. I think it was 900 volts dc and had several
large electrolytics about 3/4 the size of a soda can. Residual voltage
caused my arms to fly outward and I stabbed a friend in the shoulder
with one pair or the hemostats.


Ouch !
Click to expand...

--
Best Regards:
Baron.
 
In article <ipCdnVpbGqRrm_XQnZ2dnUVZ_hudnZ2d@earthlink.com>, Michael A.
Terrell <mike.terrell@earthlink.net> writes

All that proves is that you live in a 'nanny state'.
Click to expand...
Actually, it proves that we have a well designed and well thought out
premises wiring code which protects people and the appliances they use.
And we can actually boil a kettle in a reasonable amount of time.

What are the figures for electrical fires in the USA again?

--
Mike Tomlinson
 
On Mon, 28 Feb 2011 11:19:25 +0000, Mike Tomlinson
<mike@jasper.org.uk> wrote:

What are the figures for electrical fires in the USA again?
Click to expand...
310 deaths last year. About 1/3 of the electrical fires involve
electrical shorts of some sort. Even with fuses in the power plugs,
shorts in the walls will have the same effect in both systems:
<http://www.interfire.org/features/electric_wiring_faults.asp>
...for 1993 - 1997 are that 41,200 home structure fires
per year are attributed to ‘electrical distribution.’ These
electrical distribution fires account for 336 civilian deaths,
1446 civilian injuries, and $643.9 million in direct property
damage per year.

<http://www.nfpa.org/assets/files//PDF/Proceedings/Ahrens_presentation.pdf>

<http://www.usfa.dhs.gov/citizens/home_fire_prev/electrical.shtm>
During a typical year, home electrical problems account for
28,600 fires and $1.1 billion in property losses. 53% of
residential electrical fires involve electrical wiring.

I couldn't find any statistics for UK.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
Mike Tomlinson wrote:
In article ?ipCdnVpbGqRrm_XQnZ2dnUVZ_hudnZ2d@earthlink.com?, Michael A.
Terrell ?mike.terrell@earthlink.net? writes

? All that proves is that you live in a 'nanny state'.

Actually, it proves that we have a well designed and well thought out
premises wiring code which protects people and the appliances they use.
And we can actually boil a kettle in a reasonable amount of time.

What are the figures for electrical fires in the USA again?
Click to expand...

They are available online if you really care.

What are the figures for the UK?


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.
 
Jeff Liebermann wrote:
On Mon, 28 Feb 2011 11:19:25 +0000, Mike Tomlinson
mike@jasper.org.uk> wrote:

What are the figures for electrical fires in the USA again?

310 deaths last year. About 1/3 of the electrical fires involve
electrical shorts of some sort. Even with fuses in the power plugs,
shorts in the walls will have the same effect in both systems:
http://www.interfire.org/features/electric_wiring_faults.asp
...for 1993 - 1997 are that 41,200 home structure fires
per year are attributed to ‘electrical distribution.’ These
electrical distribution fires account for 336 civilian deaths,
1446 civilian injuries, and $643.9 million in direct property
damage per year.

http://www.nfpa.org/assets/files//PDF/Proceedings/Ahrens_presentation.pdf

http://www.usfa.dhs.gov/citizens/home_fire_prev/electrical.shtm
During a typical year, home electrical problems account for
28,600 fires and $1.1 billion in property losses. 53% of
residential electrical fires involve electrical wiring.

I couldn't find any statistics for UK.
Click to expand...
20,000/year electrical fires, etc. in the UK according to:

http://www.communities.gov.uk/news/corporate/1824335

3,000/year in Ontario Canada (about thirteen million folks):

http://www.niagarafalls.ca/city_hall/departments/fire_services/prevention/electricalfirehazards.asp

John :-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."
 
In article <IrSdnSmKNKGoYPbQnZ2dnUVZ_h2dnZ2d@earthlink.com>, Michael A.
Terrell <mike.terrell@earthlink.net> writes

They are available online if you really care.
Click to expand...
Evasion of question noted.

--
(\__/)
(='.'=)
(")_(")
 
Mike Tomlinson wrote:
In article <IrSdnSmKNKGoYPbQnZ2dnUVZ_h2dnZ2d@earthlink.com>, Michael A.
Terrell <mike.terrell@earthlink.net> writes

They are available online if you really care.

Evasion of question noted.
Click to expand...

Evasion? Numbers for both the US and UK were posted in this thread.
From what I saw, the UK is a huge tnderbox of poorly wired buildings.
Then, multiply the UK numbers by 5 to compare them to the US.

--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top