I'm working on this +15 -15 PSU with a couple of LM338 chips. The input comes from two separate 0-15Vrms 2Arms transformers, giving about 20V DC after the rectifier, on a 4700uF cap.
The thing is... I connected the LM338 (TO-3 packing) to the circuit, and it didn't work (0V on both other legs). I checked and rechecked a lot of times, tried both sources, and it didn't work. Then I had the great Idea of testing with the other LM338 I bought, and it worked. So the problem is that that IC was spoiled.
Now, I took a look at the spoiled IC, and it was ugly. Looked old, not very shiny, the writings over it a little faded. The one that was working was bright, and good to read.
So I took the IC to the store, and eventually convinced the balconist to give me another one. I think what convinced her was seeing that it really looked bad, while all other new ICs were so beautiful and shiny...
So, what's your oppinion? Any chance that it was really me who spoiled the IC somehow?? Does anybody know of someone who has spoiled a LM338 working with that voltage level? Notice that my board also had the two standard protection diodes.
Or could it be a fake??
The thing is... I connected the LM338 (TO-3 packing) to the circuit, and it didn't work (0V on both other legs). I checked and rechecked a lot of times, tried both sources, and it didn't work. Then I had the great Idea of testing with the other LM338 I bought, and it worked. So the problem is that that IC was spoiled.
Now, I took a look at the spoiled IC, and it was ugly. Looked old, not very shiny, the writings over it a little faded. The one that was working was bright, and good to read.
So I took the IC to the store, and eventually convinced the balconist to give me another one. I think what convinced her was seeing that it really looked bad, while all other new ICs were so beautiful and shiny...
So, what's your oppinion? Any chance that it was really me who spoiled the IC somehow?? Does anybody know of someone who has spoiled a LM338 working with that voltage level? Notice that my board also had the two standard protection diodes.
Or could it be a fake??