803T seems to be bad

I removed a 803T from a HD drive and it will not work. It was still in the heatsink and the ribbon cable had not been removed so it had not yet been touched with a soldering iron. I tried to test it before driving it with a DMM on diode test but it justs shows open no matter which leads I connect to... Do these diodes test like a normal diode? Should I be able to read any resisistance between the case or - lead and the + lead or will it be an open? I installed this same diode in a DDL driver circuit limited at 50 to 100ma and it did not work? Unfortunately I tried with another 803T with the same results... What do you think is happening?

One of my 803t's didnt work in a micro flexdrive. I ordered another one, but i havent tested it yet.

Check your pin connection. Here is a link to a picture;

http://www.laserpointerforums.com/forums/YaBB.pl?num=1209940381/180

Yea, that was the first thing I was thinking, pin connection is wrong. The middle pin is just a direct connect to the case and nothing else, so it will always appear open. No different than testing a length of copper wire.

Thanks everyone for the info... apex007 - are you saying that the pin connected to the case is not the - lead for the diode? If thats the case then I do have it connected incorrectly! So when looking at the leads the top pin is + ,the bottom pin is -, and the pin to the right (connected to the case) is not used and is not the - diode pin?
Thanks again for the help!

gerg said:

Thanks everyone for the info...  apex007 - are you saying that the pin connected to the case is not the - lead for the diode?  If thats the case then I do have it connected incorrectly!  So when looking at the leads the top pin is + ,the bottom pin is -, and the pin to the right (connected to the case) is not used and is not the - diode pin?
Thanks again for the help!

Click to expand...

Correct! This is a great setup for putting them in custom hosts though, because it allows us to have the case be either positive, negative, or completely insulated from the diode depending on what your setup requires!  

Another note is that most DMMs will not register the diode voltage on the violet diodes since it is arond 3V.

gerg said:

Thanks everyone for the info... apex007 - are you saying that the pin connected to the case is not the - lead for the diode? If thats the case then I do have it connected incorrectly! So when looking at the leads the top pin is + ,the bottom pin is -, and the pin to the right (connected to the case) is not used and is not the - diode pin?
Thanks again for the help!

Click to expand...

That's correct, here's the pinout: