testing capacitors - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 24th September 2004, 03:39 PM   #1
xcortes is offline xcortes  Mexico
diyAudio Member
 
Join Date: Feb 2004
Location: Mexico City
Default testing capacitors

When building my first gainclone I blew (literally) a couple of psu's. The diodes are easy to replace but the caps are harder for me to get living in Mexico.

I'd like to know if they still work so that I can use them for other amps (I have the other parts, including transformers, waiting to buid a pair of active woofers to go with a pair of 3 litre Jordans).

How can I know whether the caps are damaged or not?

BTW: my first gainclone works perfectly now. I didn't kill myself or set the house in fire in the process of building it!
  Reply With Quote
Old 24th September 2004, 04:09 PM   #2
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
I have over 40 years of DIY'ing -- in my youth in the physics lab (even though I was a chem major) , then mostly ham radio equipment, instrumentation, audiophile stuff and programming -- embarrassingly I blew up the caps on several GC's I built by soldering them incorrectly ! Welcome to the club, it proves that we are mortal !

FWIW I use 1000u/63VDC electrolytics bypassed with 10N/100V mylars on the supply rails. All the other bypass caps are 100V. I have used a number of different input caps including 100V EPCOS silver caps, mylar caps from Mouser (B.C. Components) and some exotic General Electric and Corning caps.
  Reply With Quote
Old 24th September 2004, 08:05 PM   #3
diyAudio Member
 
falcott's Avatar
 
Join Date: Jul 2004
Location: Wherever I hang my hat...
Default Re: testing capacitors

Quote:
Originally posted by xcortes
How can I know whether the caps are damaged or not?

I use a multimeter that measures capacitance. Mine measures from 40nF to 100uF, so I cannot check things like 1000uF decoupling caps...
__________________
"Everything should be made as simple as possible, but not simpler." - Einstein
  Reply With Quote
Old 24th September 2004, 08:49 PM   #4
Mr Evil is offline Mr Evil  United Kingdom
diyAudio Member
 
Join Date: Aug 2004
Location: Behind you
You can put the 1000uF cap in series with a < 100uF one and measure the difference from the < 100uF alone, since the total will be less than 100 and thus within you meter's range. The value of the 1000uF cap can be calculated from that.
__________________
https://mrevil.asvachin.eu/
  Reply With Quote
Old 24th September 2004, 08:50 PM   #5
johnnyx is offline johnnyx  United Kingdom
diyAudio Member
 
Join Date: Jan 2004
Location: manchester
The caps are probably ok.

It's not always useful to measure capacitance to test for failure. I use three capacitance meters; one on my Fluke DMM, and two stand-alone capacitance meters.
When a capacitor fails it is usually due to leaking electrolyte or evaporation due to age. Measurements of capacitance show a small change, but within tolerance, for the DMM and one of the cap meters. The other meter shows a greater reduction of capacitance for faulty caps. So only one of the three shows a faulty cap as being faulty. The others would show it as being ok.
It depends how they measure it, a leaky cap has a higher impedence (esr etc), which doesn't always show-up in the capacitance reading.
Cyril Bateman designed a meter in Electronics World that would show faulty caps, but it isn't simple, partly because losses are frequency dependant.
  Reply With Quote
Old 26th September 2004, 04:42 AM   #6
diyAudio Member
 
thomas997's Avatar
 
Join Date: Feb 2004
Location: Vancouver
Build an ESR meter then.

Here is one example:

http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
  Reply With Quote
Old 26th September 2004, 04:47 AM   #7
diyAudio Member
 
falcott's Avatar
 
Join Date: Jul 2004
Location: Wherever I hang my hat...
And another:

http://www.siliconchip.com.au/cms/A_100895/article.html
__________________
"Everything should be made as simple as possible, but not simpler." - Einstein
  Reply With Quote
Old 29th September 2004, 03:55 AM   #8
diyAudio Member
 
thomas997's Avatar
 
Join Date: Feb 2004
Location: Vancouver
Quote:
Originally posted by falcott
And another:

http://www.siliconchip.com.au/cms/A_100895/article.html

Thanks!


Oh and dont read this:
[SIZE=0.6]If you dont happen to have 9$ to spend, use a certain search engines cache feature to reveal the full article.[/SIZE]
  Reply With Quote
Old 29th September 2004, 06:32 AM   #9
diyAudio Member
 
falcott's Avatar
 
Join Date: Jul 2004
Location: Wherever I hang my hat...
Quote:
Originally posted by thomas997
Oh and dont read this:
[SIZE=0.6]If you dont happen to have 9$ to spend, use a certain search engines cache feature to reveal the full article.[/SIZE]

Oops... I found this by doing a search with a certain search engine, and didn't realise that they charged for viewing more than the first paragraph or 2. Glad you found a way to get the whole deal.

(If anyone asks, I never read a thing....)
__________________
"Everything should be made as simple as possible, but not simpler." - Einstein
  Reply With Quote
Old 30th September 2004, 07:21 PM   #10
diyAudio Member
 
falcott's Avatar
 
Join Date: Jul 2004
Location: Wherever I hang my hat...
By the way, for those interested, part 2 of the above article is:

http://www.siliconchip.com.au/cms/A_101187/article.html

with a couple of interesting links to the author's website at the bottom of the article.
__________________
"Everything should be made as simple as possible, but not simpler." - Einstein
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
what is the difference between silver mica capacitors and ceramic capacitors ?? prorms Solid State 1 6th May 2008 12:38 PM
whats the best way of testing electrolytic capacitors using a multimeter? mrsmith Solid State 19 9th November 2005 08:33 AM
testing electrolytic capacitors using a multimeter? mrsmith Parts 3 22nd October 2005 06:10 PM
Testing paper-in-oil capacitors jim Tubes / Valves 1 8th February 2003 03:27 PM
Testing capacitors in circuit. Tony D. Parts 1 22nd September 2002 12:14 PM


New To Site? Need Help?

All times are GMT. The time now is 03:50 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2