Testing op amps

[michouthefirst]

I bought a bunch of op amps on ebay and I am doubt they are fake. How can I tell?

For instance, I try to null offset a TL071 and it always show at least 300mV at the output (+/- 16 V supply, both inputs at 0 V) as shown on the data sheet, with a 100K pot and a 1.5K resistor connected to Vcc-.

Is it the amp is defective or I do it wrong?

 

[WSJ]

http://www.diyaudio.com/forums/analog-line-level/220535-discrete-opamp-test-circuits.html

 

[peranders]

You must have some feedback. Just connecting the inputs together won't work. The circuit above is a good start.

 

[michouthefirst]

Thank you guys, I will try that.