How do you test transistors?

Knertified · 29th July 2004, 09:55 PM

Everyone says to test the transistors on a broke amp because they are usually the culprit. I see that some people desoder them first and some people don't. Some people say you can use a multimeter and some say you need other tools. My amplifer is broken but nothing is physically damaged. Could someone point me in the right direction?

Netlist · 30th July 2004, 06:56 AM

I keep recommending this nice fellow's site:
http://www.bcae1.com/

/Hugo

Vivek · 30th July 2004, 08:36 AM

If I was in your place, I would remove the transistors and test them like one tests a diode. Most DMMs have a diode test facility. Use that.

Vivek

NB23 · 30th July 2004, 10:35 PM

If you don't have a transistor or diode tester, you could easily use an ohmmeter on your multimeter. You need to make sure that if it is a bipolar or FET tranistor. Bipolar tranistors could either be NPN or PNP. FET's could be JFET's, MOSFET's, etc... Most commonly amplifiers use NPN tranistors or modern amplifiers use MOSFET's N-channels I think. Oh yea, there are two types of MOSFET's N-channel, and P-channel. The gate to source and drain on an ohmeter should read about 35ohms(varies on each transitor). Drain to source should have continuity. It would be easier to check out bcae1, great website if your getting into electronics and/or car audio.

Knertified · 31st July 2004, 02:45 AM

Thank you everyone for all your help!

29th July 2004, 09:55 PM	#1
Knertified diyAudio Member Join Date: Jul 2004 Location: Springfield, MA	How do you test transistors? Everyone says to test the transistors on a broke amp because they are usually the culprit. I see that some people desoder them first and some people don't. Some people say you can use a multimeter and some say you need other tools. My amplifer is broken but nothing is physically damaged. Could someone point me in the right direction?

30th July 2004, 08:36 AM	#3
Vivek diyAudio Member Join Date: Nov 2000 Location: Bangalore, India	If I was in your place, I would remove the transistors and test them like one tests a diode. Most DMMs have a diode test facility. Use that. Vivek __________________ Thank God for DIY audio.

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30th July 2004, 06:56 AM	#2
Netlist diyAudio Moderator Emeritus Join Date: Jan 2003	I keep recommending this nice fellow's site: http://www.bcae1.com/ /Hugo

30th July 2004, 10:35 PM	#4
NB23 diyAudio Member Join Date: Jun 2004 Location: indiana	If you don't have a transistor or diode tester, you could easily use an ohmmeter on your multimeter. You need to make sure that if it is a bipolar or FET tranistor. Bipolar tranistors could either be NPN or PNP. FET's could be JFET's, MOSFET's, etc... Most commonly amplifiers use NPN tranistors or modern amplifiers use MOSFET's N-channels I think. Oh yea, there are two types of MOSFET's N-channel, and P-channel. The gate to source and drain on an ohmeter should read about 35ohms(varies on each transitor). Drain to source should have continuity. It would be easier to check out bcae1, great website if your getting into electronics and/or car audio.

31st July 2004, 02:45 AM	#5
Knertified diyAudio Member Join Date: Jul 2004 Location: Springfield, MA	Thank you everyone for all your help!