Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Mar Tue 26, 2019 7:52 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 28 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: Check your new electrolytics before installing
PostPosted: Sep Wed 19, 2018 8:50 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 30536
Location: SoCal, 91387
allied333 wrote:
Rare, but I bought 4 bad new electrolytic capacitors. Leaked so bad it pulled down the voltage thru a resistor network. Another new cap fixed the problem.

There's a lesson to be learned there; always test new caps.

Awhile back I installed a new metallized polypropylene cap in a home-brew set I was building, and eventually determined that it's lack of performance was due to the cap being NG.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins//////////////////


Top
 Profile  
 
 Post subject: Re: Check your new electrolytics before installing
PostPosted: Sep Thu 20, 2018 12:27 pm 
Member
User avatar

Joined: May Wed 01, 2013 10:05 pm
Posts: 1990
Location: Rayleigh, BC, CANADA
I even got a couple of bad caps with a brand new tone control kit from China, so ya, always check them.


Attachments:
Tone Control Kit.JPG
Tone Control Kit.JPG [ 42.07 KiB | Viewed 691 times ]

_________________
Rocco
Top
 Profile  
 
 Post subject: Re: Check your new electrolytics before installing
PostPosted: Sep Thu 20, 2018 12:41 pm 
Member
User avatar

Joined: Feb Sun 01, 2015 9:37 pm
Posts: 423
Location: Laflin, PA
Leigh wrote:
Some years ago, several major manufacturers produced entire runs of defective electrolytics.
This was due to a missing element in the chemistry of the electrolyte.

Hopefully all of those are in landfills, but you never know.

It's always possible for problems to exist on a smaller scale and get by Quality Control.
Of course, that assumes the manufacturer has such a department in the first place.

- Leigh

I remember this well! IBM/Lenovo used them in their motherboards and ended up replacing many defective units and causing me a bunch of grief. As I recall the caps were "Chinese Made" using stolen Japanese technology minus that key ingredient. Every one of the caps had stuff leaking out of the blown tops.

_________________
Bob
73's WA3TVH


Top
 Profile  
 
 Post subject: Re: Check your new electrolytics before installing
PostPosted: Sep Thu 20, 2018 10:00 pm 
Member
User avatar

Joined: Dec Tue 23, 2014 6:51 pm
Posts: 1086
Location: N. Palm Bch, Fl.
The company I worked for was one of the companies that did service work for IBM/Lenovo. Laptop-Desktop systems. We had so much work that we had to hire contractors who got paid by the job. They would show the manager how to spot the bubbled top and put in a service call. They made a ton of money that year. Sony got nailed also, but not to the extent that IBM did. We serviced Apple too and I never saw one mother board with bulging cap. I hated Apple because they were a bear to work on, but they put out a quality product. Our sale people would sign any contract and I've worked on some real junk. Gateway-- You carried Band-Aids and antiseptic in the van.

Freeman


Top
 Profile  
 
 Post subject: Re: Check your new electrolytics before installing
PostPosted: Sep Sun 23, 2018 11:22 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 994
Location: Detroit, Michigan
I Worked for DEC/Compac, and we had a customer who had thousands of LG pc's under service contract. One particular generation got hit with the capacitor plague. The service philosophy was sub-assembly replacement, I lost count of how many motherboards I replaced, got to be in the many hundreds. Some caps would bulge the top vents, some would leak the brown electrolyte, some would blow the cans clean off, and others would blow and unwind the insides. I have to say, good job security while it lasted.


Top
 Profile  
 
 Post subject: Re: Check your new electrolytics before installing
PostPosted: Sep Mon 24, 2018 4:31 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 30536
Location: SoCal, 91387
Kevin Clark wrote:
The service philosophy was sub-assembly replacement, I lost count of how many motherboards I replaced, got to be in the many hundreds.

Board swapping in consumer electronics became a cost cutting measure back in the '70's, as lesser skilled (and paid) personnel could do that, vs paying a tech to do component level troubleshooting. Not at all surprising that it carried over into PC's.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins//////////////////


Top
 Profile  
 
 Post subject: Re: Check your new electrolytics before installing
PostPosted: Oct Sun 28, 2018 2:16 pm 
New Member

Joined: Oct Sat 27, 2018 2:26 pm
Posts: 10
Location: Copenhagen, Denmark
HERSHEY wrote:
I just want to offer the suggestion to all to check those new electrolytics before you install them. In the last 6 months, I've put into 2 radios new electrolytics that were bad.


Leigh wrote:
Some years ago, several major manufacturers produced entire runs of defective electrolytics.
This was due to a missing element in the chemistry of the electrolyte.
...
- Leigh


The best way to test (electrolytic) capacitors; measure ESR:
https://en.wikipedia.org/wiki/Equivalent_series_resistance


Capacitor Testing, Safe Discharging and Other Related Information
Version 2.42 (22-Nov-05):
http://www.repairfaq.org/sam/captest.htm
Quote: "...
Before I bought my ESR meter I too wondered--what exactly did it measure? Nevertheless, having heard so much about the meter, I went ahead and bought one. It works, and that's the real bottom line.
...
The objective of the ESR meter is to identify capacitors that have gone bad. This is more the case with electrolytics where the dielectric compound tends to dry up.
..."

An Equivalent Series Resistance Meter:
http://ludens.cl/Electron/esr/esr.html
Quote: "...With my ESR meter I quickly found five electrolytic capacitors which had degraded a lot...one had 6 Ohm, one 7 Ohm, and the other two had such high ESR that the meter wouldn't even deflect!..."

An AC-coupled ESR-tester can also test battery/accumulator cells:

Hints for techs using Bob Parker's ESR meter(kit)...:
https://web.archive.org/web/20170613142945/https://www.flippers.com/esrkthnt.html
http://www.flippers.com/esrkthnt.html
Quote: "...Bob Parker's excellent ESR meter (January 1996) will also test all types of cells and batteries..."

E.g.:

Good and simple:
Analogue ESR-meter - in the right side of the schematic there is a table with max. ESR:
https://web.archive.org/web/20161209090646/http://members.shaw.ca/swstuff/esrschematic.png
Description: Capacitor ESR Tester:
https://web.archive.org/web/20160621020936/http://members.shaw.ca:80/swstuff/esrmeter.html

-

A super de luxe component tester, including ESR and electrolytic capacitors, with AVR-microcontroller and source code in two different versions. The schematic can be found in many versions - even of manufactured versions. Warning: The tester do not survive plugging in a charged capacitor :shock: I acquired two just in case:

Transistor tester (actually much more than a transistor tester; a component tester):
Main description:
http://www.mikrocontroller.net/articles/AVR_Transistortester
Former description:
http://www.mikrocontroller.net/articles/AVR-Transistortester
Manual:
https://www.mikrocontroller.net/articles/AVR_Transistortester#Downloads_.28English.29
Source code:
http://www.mikrocontroller.net/svnbrowser/transistortester/

The Transistor tester can be bought at Ebay in many versions (LCD types; graphics, monochrome, color... Case og no case) - e.g.:

Through-hole version (Red PCB):
https://www.ebay.com/sch/i.html?&_nkw=Transistor+tester+gm328

SMD version (black PCB):
https://www.ebay.com/sch/i.html?&_nkw=Transistor+tester+gm328A

-

Capacitor plague:
https://en.wikipedia.org/wiki/Capacitor_plague
Quote: "...
The capacitor plague was a problem related to a higher-than-expected failure rate of non-solid aluminum electrolytic capacitors, between 1999 and 2007, especially those from some Taiwanese manufacturers,[1][2] due to faulty electrolyte composition that caused corrosion accompanied by gas generation, often rupturing the case of the capacitor from the build-up of pressure.
..."

Strategies to Repair or Replace Old Electrolytic Capacitors
https://web.archive.org/web/20180106070321/https://www.nmr.mgh.harvard.edu/~reese/electrolytics/
Quote: "...
Electrolytics do not suffer idleness well. They can cause big trouble when idle for long periods, needing periodic charging to stay "formed" and maintain the oxide layer that insulates the conducting plates. Sometimes they can be "reformed" by a slowly rising return to working voltage (see below). Even with regular use, electrolytics fail with age by drying out or leaking electrolyte following internal corrosion. If the electrolytic bulges, shows obvious loss of electrolyte, or simply can't be reformed you must replace it.
...
Reforming
..."

_________________
OZ1HFT, Glenn


Top
 Profile  
 
 Post subject: Re: Check your new electrolytics before installing
PostPosted: Feb Sat 09, 2019 11:53 am 
Member
User avatar

Joined: Nov Wed 09, 2011 4:07 am
Posts: 625
Location: MD-DC 20855
BikeNEPA wrote:
Leigh wrote:
Some years ago, several major manufacturers produced entire runs of defective electrolytics.
This was due to a missing element in the chemistry of the electrolyte.

Hopefully all of those are in landfills, but you never know.

It's always possible for problems to exist on a smaller scale and get by Quality Control.
Of course, that assumes the manufacturer has such a department in the first place.

- Leigh

I remember this well! IBM/Lenovo used them in their motherboards and ended up replacing many defective units and causing me a bunch of grief. As I recall the caps were "Chinese Made" using stolen Japanese technology minus that key ingredient. Every one of the caps had stuff leaking out of the blown tops.


So did Dell. I replaced a few of this type 'low ESR' cap on the
mother board of an old Dell XPS600 that I was given. They
were leaking electrolyte on top, having vented just enough
to relieve pressure.

David

P.S. Testing ESR is a good idea. I have several of the inexpensive
Chinese multi-function testers. One of them, which tests a variety
of electronic components such as diodes and transistors, also
tests resistance and capacitance, and it seems to have a pretty
good ESR testing feature. How accurate it is I have no idea- but it
does a good job, I believe, in Identifying caps with ESR problems.
It's amazing just how cheap these various tester boards are, for
what they do!

I routinely measure electrolytics for capacitance and then reform
them to make sure I get an acceptably low and steady leakage
reading. I don't that often test for ESR, but I probably should.

_________________
Clutter


Top
 Profile  
 
Post New Topic Post Reply  [ 28 posts ]  Moderator: Chuck Schwark Go to page Previous  1, 2

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest



Search for:
Jump to:  




























Privacy Policy :: Powered by phpBB