Wd diamondmax 21 pata

Sorry for double post I made an error.

inverted polarity on stm3320820a smoke on pwm diode is there someone in italy that can change diodes?
the hdd is stm3320820a fw:3AAE P.N:9DP03G-326 TK DATA CODE 7276
I have 2 other hdd fw:3AAE P.N:9DP03G-326 TK DATA CODE 8397
3AAE P.N:9DP03G-326 TK DATA CODE 7383

I made some measurements.

In test diode 5v and ground are in conduction on + of diode.

test pins of diode and it’s in conduction.

Thanks to all.


I made tests indicated by fzabakar in his wonderful guide.

I so think there is a short. Can i change diode or risk to damage something else without protection.?

If i remove diode then what are measurement i can do to be calm that everithings are ok?

Obviously no short on removed diode pin , but also can i check conductivivity between ground and -pin of diode and no conductivity between ground and + pin of removed diode.And test of 5v?

Sorry for my english and  thanks to all.


I don’t know if you saw this series by fzabkar  http://community.wd.com/t5/External-Drives-for-PC/connected-wrong-power-supply-to-3TB-WD-My-Book-Essential-any-way/td-p/837943 he’s posted quite a bit lately and is the only one who understands these boards. 


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I read the post and i do the tests that Fzakabar share with us.

Thank to all for this helpful forum. I resolve removing diode pwm.