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Author Topic: how do I test electronic components?  (Read 6402 times)

Offline Geoff_T

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Re: how do I test electronic components?
« Reply #15 on: October 10, 2004, 01:58:00 pm »
Hi

I just thought I'd chime in with a couple of pointers...

1. You can test transistors and diodes with the multimeter set to the "diode symbol" (rather than ohms). If you, for instance, put one probe on the centre wire of a transistor, you should get either infinity or around 600mV if you touch the other probe on either of the two outer legs. If you reverse the leads you will find that the readings reverse... or should do.

2. The problem with checking resistor values directly on a pcb is that other resistors might be in parallel with it (like the base bias resistors on a transistor via the power supply) and, if the resistor is not close to the colour band value, it's a good idea to unsolder one leg of the resistor and pull it out of the pcb. Then check the resistance value again and external influences will have been removed.

Smile
Geoff Tanner
http://www.auroraaudio.net/main.shtml
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    http://www.amazon.com/gp/reader/0595093329/ref=sib_dp_pt/104 -6861899-0350336#reader-link

NB Please do not pm me if you want a fast response... please email me.

Offline Brian Roth

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Re: how do I test electronic components?
« Reply #16 on: October 11, 2004, 12:55:29 am »
Hi, Geoff!  I thought I'd add to your comments.  Many plastic transistors follow the "emitter-base-collector" wire lead sequence, but not all do.  Some have the base at one end or the other instead of the middle lead.  Those tend to me transistors from Europe or Asia vs. the USA.

For checking transistors, I've kept an ancient, beat-to-hell analog VOM in my tool kit.  I've used it enough to have a "feel" of how a transistor should "look" on the meter.  I guess I'm a Luddite since I've had variable luck using a digital meter to check transistors in-circuit.

I'm glad you also reiterated the possibility of "bogus" readings with a component still soldered into the cirsuit.

Bri



Brian Roth Technical Services
Oklahoma City, OK
www.BrianRoth.com

Offline Barish

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Re: how do I test electronic components?
« Reply #17 on: October 11, 2004, 10:17:53 am »
For those who feel themselves too lazy to be bothered with good old fashion way of testing transistors, there is a doc's pager sized mini test device called Atlas DCA-55 Semiconductor Component Analyser from a UK company called Peak Electronics. It costs
M Ozturk

Offline Geoff_T

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Re: how do I test electronic components?
« Reply #18 on: October 11, 2004, 12:14:17 pm »
Hi

When I want to test transistors seriously (rather than just see if the junctions still function) I use an old Heathkit tester that you can buy off eBay for peanuts. It has a great big, easy to read, meter and comes in a neat carry case.

Like this one....

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=1 504&item=3845417150&rd=1

Smile
Geoff Tanner
http://www.auroraaudio.net/main.shtml
http://www.grandmasterrecorders.com
    http://www.amazon.com/gp/reader/0595093329/ref=sib_dp_pt/104 -6861899-0350336#reader-link

NB Please do not pm me if you want a fast response... please email me.

Offline Sahib

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Re: how do I test electronic components?
« Reply #19 on: October 12, 2004, 06:00:22 pm »
Barish wrote on Mon, 11 October 2004 15:17

For those who feel themself too lazy to be bothered with good old fashion way of testing transistors, there is a doc's pager sized mini test device called Atlas DCA-55 Semiconductor Component Analyser from a UK company called Peak Electronics. It costs

Offline bobkatz

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Re: how do I test electronic components?
« Reply #20 on: October 12, 2004, 06:08:02 pm »
I like that Atlas box you describe, Barish! Saves a lot of time and trouble!


Wonder how it will do with a transistor that's in circuit...

BK
There are two kinds of fools,
One says-this is old and therefore good.
The other says-this is new and therefore better."

No trees were killed in the sending of this message. However a large number of
electrons were terribly inconvenienced.

Offline Seeker-Ian

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Re: how do I test electronic components?
« Reply #21 on: October 13, 2004, 12:01:59 pm »
Thanks for the link Geoff. i am currently the top bidder of that heath kit tester.

BTW Bob.. i enjoyed your book. very nice and worth every penny.

an update on my problem... I replaced the transisters for this section of my mix bus and it returned my volume on the right mix bus but.. the distortion is still there. getting closer. next step is the caps though they all look new.

ideas?





Offline Sahib

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Re: how do I test electronic components?
« Reply #22 on: October 13, 2004, 02:48:47 pm »
bobkatz wrote on Tue, 12 October 2004 23:08

I like that Atlas box you describe, Barish! Saves a lot of time and trouble!


Wonder how it will do with a transistor that's in circuit...

BK


Bob,

Unfortunately it does not measure on the circuit. But it is still a great device. There is another version available from the same company which tests LCR.

Cemal

Offline Barish

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Re: how do I test electronic components?
« Reply #23 on: October 13, 2004, 06:36:06 pm »
bobkatz wrote on Tue, 12 October 2004 23:08

I like that Atlas box you describe, Barish! Saves a lot of time and trouble!


Wonder how it will do with a transistor that's in circuit...

BK


Hi Bob,

As Sahib and the user manual of Atlas said, "it is designed to test discrete, unconnected, unpowered semiconductor components". An FAQ document is available on the product page on their website (or alternatively here).

I'm not aware of a tester that is capable of measuring components connected on the board without getting confused by the rest of the circuit.

Regards,

Mahcem
M Ozturk

Offline OOF!

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Re: how do I test electronic components?
« Reply #24 on: October 13, 2004, 07:02:05 pm »
hey ck,
this is the perfect forum for this question.  i've learned so much from these guys.
additionally, everything you need to know can be found on the web.  search under various words and you'll get all the instruction you need.  i couldn't believe all the useful info i got and it put me on the way to learning this stuff.  here are a few of the more useful links i found.

http://www.doctronics.co.uk/scope.html
http://www.cs.tcd.ie/courses/baict/bac/jf/labs/scope/oscillo scope.html
http://www.cs.tcd.ie/courses/baict/bac/jf/labs/scope/termino logy.html
http://www.cs.tcd.ie/courses/baict/bac/jf/labs/scope/setting .html
http://www.cs.tcd.ie/courses/baict/bac/jf/labs/scope/control s.html
http://www.cs.tcd.ie/courses/baict/bac/jf/labs/scope/meastec h.html

also, get yourself a tektronics scope on ebay. they're invaluable- around 250 bucks.
good luck,
david lawrence

OOF!