I substituted some opamps, now I'm nervous

[Mooly]

They are now running warm. My only concern is the labeling on those on one of the boards has faded. Labelling is fine in the other board. I have no worries about them being fakes.

Purchased from digikey

The markings can be quite faint and hard to read on some devices, they are on mine (from RS)

How do you test for fakes? Your prices (lm4562na) are lower than digikey, which normally would send up red flags. If it's easy I'd like to test one of mine, I have extras.

The proper way is to test all the main parameters meet the spec (not easy, time consuming, and needs a variety of good test equipment)

Diy method... build two identical circuits (say a x10 DC coupled stage) using a known genuine device and then compare current draw, offsets and most importantly AC performance. Do that by driving each at high frequency (100kHz to 1Meg region) from a good squarewave generator and make sure both outputs are essentially identical and 'overlay' each other on a good dual trace scope. That would weed out mopst fakes, it would not eliminate out of spec devices though.

 

[Cjuried]

In deed, a fine method for a quick a/b comparison. I am lucky and grateful to own the necessary test equipment for proper quantification of specifications. With that said I rest assure that my projects will meet, at minimum, manufacturer spec of the components I'm using and I can sell authentic components.

The markings can be quite faint and hard to read on some devices, they are on mine (from RS)



The proper way is to test all the main parameters meet the spec (not easy, time consuming, and needs a variety of good test equipment)

Diy method... build two identical circuits (say a x10 DC coupled stage) using a known genuine device and then compare current draw, offsets and most importantly AC performance. Do that by driving each at high frequency (100kHz to 1Meg region) from a good squarewave generator and make sure both outputs are essentially identical and 'overlay' each other on a good dual trace scope. That would weed out mopst fakes, it would not eliminate out of spec devices though.