Recently I bought 2 LM338K regulators from an electronics component retailer which when fitted one at a time did not work at all in a power supply circuit repair. I had a dig around and found an old National Semiconductor 338K which when fitted, worked fine. These are SGS Thomson branded IC's as was a third 338K the owner fitted in an attempt to fix the unit.
I was wondering if anyone encountered similar DOA regulators?. The IC can when opened is definitely an IC with a larger power structure on the same die so it doesn't appear to be a counterfeit unit.