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OT: various electronics questions by "newone"
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newone



Joined: 21 Dec 2005
Posts: 8

PostPosted: Wed Dec 21, 2005 12:50 pm    Post subject: OT: various electronics questions by "newone" Reply with quote

how to know the transistor is npn or pnp


pleasw whith full detail
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newone



Joined: 21 Dec 2005
Posts: 8

PostPosted: Wed Dec 21, 2005 12:52 pm    Post subject: how to check 400v capacitor whith analog meter Reply with quote

how to check 400v capacitor whith analog meter is breakdown or not
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zaphod7501



Joined: 02 Aug 2004
Posts: 527
Location: Peoria Illinois

PostPosted: Wed Dec 21, 2005 10:30 pm    Post subject: Reply with quote

newone wrote:
how to check 400v capacitor whith analog meter is breakdown or not

Most meter tests will be one-way tests. You can test for a failed part but you can't test for a good part. In other words, if a test says it's bad then it's probably bad. If a test says it's good then you don't know anything.

The voltage of a capacitor is irrelevant for testing purposes and cannot be tested without destroying the part. (exceeding the voltage rating will usually damage the part) The capacitance (uf or microfarads) can be tested with special testers and not with a VOM. You can test for a short (0-100 ohms) and a large power supply filter will show a temporary short which goes away as the filter charges. An analog meter cannot test capacitors unless it has a built-in testing function.
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zaphod7501



Joined: 02 Aug 2004
Posts: 527
Location: Peoria Illinois

PostPosted: Wed Dec 21, 2005 10:51 pm    Post subject: Reply with quote

newone wrote:
how to know the transistor is npn or pnp

If the part has markings they might tell you. Axxx or Bxxx are usually PNP (example A701 stands for 2SA701 which stands for a PNP). Cxxx and Dxxx are NPN (D2588 = 2SD2588 which is an NPN). Kxxx are FET's. If you are going to search (Google?) for a number, you need to include the '2S' prefix which is not actually on the part but is part of the type number.

If you know the leads (base, collector, emitter) then you can figure out the type by measuring accross the base - emitter junction. positive on base and negative on emitter will conduct slightly (x100 range) with an NPN but not a PNP.

There is a more complicated series of meter tests for transistors but I'd have to dig back through years of old literature. This should get you started
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newone



Joined: 21 Dec 2005
Posts: 8

PostPosted: Thu Dec 22, 2005 12:50 am    Post subject: how to check the regulator ic is short LM317T Reply with quote

how to check the regulator ic is short or open or lekage

THE IS INFORMATION IS

LM317T
CC01P VW
MAR 507


THE IC IS IN MOST DIGITAL RECIEVERSE

PLEASE TELL ME WHERE TO PUT RED AND BLACK PROBES OF METER IN IC TO CHECK VOLTAGE IAM NEW IN THIS FIELD
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underquark
Expert


Joined: 20 Jun 2005
Posts: 868
Location: UK

PostPosted: Thu Dec 22, 2005 6:58 am    Post subject: Reply with quote

newone wrote:
how to know the transistor is npn or pnp

Click on the pictures for further info.:


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zaphod7501



Joined: 02 Aug 2004
Posts: 527
Location: Peoria Illinois

PostPosted: Thu Dec 22, 2005 9:21 am    Post subject: Reply with quote

newone wrote:
how to check the regulator ic is short LM317T

Well, since I responded before, I will do it one more time; but:
You need to find a basic electronics forum or read some library books.
If you are trying to fix something JP1 related, then someone might be better able to help.
If you had done a basic Google search, you would have found that a LM317 is a variable regulator and a simple test will not tell you anything. You need technical info on the product that you are trying to fix.

Basic diagnosis: troubleshoot the product not the individual parts.
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newone



Joined: 21 Dec 2005
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PostPosted: Thu Dec 22, 2005 11:38 am    Post subject: How to know the transistor is fet and how to check it Reply with quote

how to know the transistor is fet and how to check it whith analog or digital meter

the transistor is short or damaged. and what is the best procedure to check it powerup or poweroff
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newone



Joined: 21 Dec 2005
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PostPosted: Thu Dec 22, 2005 6:55 pm    Post subject: how to know the zenor diode how much watt Reply with quote

how to know the zenor diode how much watt and how much voltage
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zaphod7501



Joined: 02 Aug 2004
Posts: 527
Location: Peoria Illinois

PostPosted: Thu Dec 22, 2005 7:53 pm    Post subject: Reply with quote

newone wrote:
how to know the transistor is fet and how to check it whith analog or digital meter

the transistor is short or damaged. and what is the best procedure to check it powerup or poweroff

Here ( http://www.eio.com/repairfaq/REPAIR/F_semitest.html ) is a discussion of meter testing of semiconductors. About half way down the page it gets into simple testing methods.
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newone



Joined: 21 Dec 2005
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PostPosted: Fri Dec 23, 2005 7:00 pm    Post subject: the best procedure to check ultra fast diode by analogmeter Reply with quote

the best procedure to check ultra fast diode by analogmeter

what is the best procedure?

how to know whith analog meter the diode is short or leckage
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newone



Joined: 21 Dec 2005
Posts: 8

PostPosted: Fri Jan 20, 2006 3:46 am    Post subject: 400 volt capacitor how to know its leckage or damaged Reply with quote

400 volt capacitor how to know its leckage or damaged



one day my own digital satellite reciver not working

itry but not fix

i went to technican and he only change the 400 volt capacitor

my capacitor was like new one


my question is how to know its leckage


i have analog and digital meter

which is best for capacitor
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zaphod7501



Joined: 02 Aug 2004
Posts: 527
Location: Peoria Illinois

PostPosted: Fri Jan 20, 2006 8:26 am    Post subject: Reply with quote

First of all, the voltage of a capacitor is not very important, the capacitance value is. (like 4.7 uf or 3300pf or 332j, etc) The voltage just has to be higher than any voltage present in the circuit. Many digital meters have a capacitor checking feature but usually only low values. (2.2uf but not 1000uf; uf = microfarads)

Capacitor checking is usually done with an oscilloscope, in circuit, by viewing the signals present on it, and determining if it is doing it's job correctly. Most likely the tech replaced it based upon past history or manufacturers reccomendation, not by testing it.
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newone



Joined: 21 Dec 2005
Posts: 8

PostPosted: Fri Apr 21, 2006 7:28 pm    Post subject: What is replace of this diode here 208 Reply with quote

What is replace of this diode here 208
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electronics_field



Joined: 06 Oct 2006
Posts: 6

PostPosted: Fri Oct 06, 2006 10:35 pm    Post subject: HOW TO KNOW THE RESISTOR IS SHORT Reply with quote

HOW TO KNOW THE RESISTOR IS SHORT

BY ANALOG METER
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