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newone
Joined: 21 Dec 2005 Posts: 8
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Posted: Wed Dec 21, 2005 12:50 pm Post subject: OT: various electronics questions by "newone" |
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how to know the transistor is npn or pnp
pleasw whith full detail |
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newone
Joined: 21 Dec 2005 Posts: 8
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Posted: Wed Dec 21, 2005 12:52 pm Post subject: how to check 400v capacitor whith analog meter |
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how to check 400v capacitor whith analog meter is breakdown or not |
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zaphod7501
Joined: 02 Aug 2004 Posts: 534 Location: Peoria Illinois |
Posted: Wed Dec 21, 2005 10:30 pm Post subject: |
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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. _________________ Just call me Zaphod (or Steve) --- I never should have started using numbers in a screen name but I just can't stop now. |
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zaphod7501
Joined: 02 Aug 2004 Posts: 534 Location: Peoria Illinois |
Posted: Wed Dec 21, 2005 10:51 pm Post subject: |
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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 _________________ Just call me Zaphod (or Steve) --- I never should have started using numbers in a screen name but I just can't stop now. |
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newone
Joined: 21 Dec 2005 Posts: 8
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Posted: Thu Dec 22, 2005 12:50 am Post subject: how to check the regulator ic is short LM317T |
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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: 874 Location: UK |
Posted: Thu Dec 22, 2005 6:58 am Post subject: |
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newone wrote: | how to know the transistor is npn or pnp |
Click on the pictures for further info.:
![](http://www.talkingelectronics.com/Projects/TransistorData/images/Transistors/Case-9.gif) |
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zaphod7501
Joined: 02 Aug 2004 Posts: 534 Location: Peoria Illinois |
Posted: Thu Dec 22, 2005 9:21 am Post subject: |
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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. _________________ Just call me Zaphod (or Steve) --- I never should have started using numbers in a screen name but I just can't stop now. |
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newone
Joined: 21 Dec 2005 Posts: 8
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Posted: Thu Dec 22, 2005 11:38 am Post subject: How to know the transistor is fet and how to check it |
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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 Posts: 8
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Posted: Thu Dec 22, 2005 6:55 pm Post subject: how to know the zenor diode how much watt |
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how to know the zenor diode how much watt and how much voltage |
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zaphod7501
Joined: 02 Aug 2004 Posts: 534 Location: Peoria Illinois |
Posted: Thu Dec 22, 2005 7:53 pm Post subject: |
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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. _________________ Just call me Zaphod (or Steve) --- I never should have started using numbers in a screen name but I just can't stop now. |
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newone
Joined: 21 Dec 2005 Posts: 8
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Posted: Fri Dec 23, 2005 7:00 pm Post subject: the best procedure to check ultra fast diode by analogmeter |
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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
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Posted: Fri Jan 20, 2006 3:46 am Post subject: 400 volt capacitor how to know its leckage or damaged |
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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: 534 Location: Peoria Illinois |
Posted: Fri Jan 20, 2006 8:26 am Post subject: |
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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. _________________ Just call me Zaphod (or Steve) --- I never should have started using numbers in a screen name but I just can't stop now. |
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newone
Joined: 21 Dec 2005 Posts: 8
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Posted: Fri Apr 21, 2006 7:28 pm Post subject: What is replace of this diode here 208 |
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What is replace of this diode here 208 |
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electronics_field
Joined: 06 Oct 2006 Posts: 6
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Posted: Fri Oct 06, 2006 10:35 pm Post subject: HOW TO KNOW THE RESISTOR IS SHORT |
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HOW TO KNOW THE RESISTOR IS SHORT
BY ANALOG METER |
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