Car keeps blowing Alt Diode?

[Exille]

Ive had this car for about 3 weeks now (93 240sx) and ive gone through 4 alternators and 3 batterys...cant seem to figure out what is causing this, ive ripped out all the shatty stereo wiring the P.O. had done plus the dead deck, supposedly every alternator i put in gets a blown diode within 30 mins...or at least thats what NAPA tells me...any ideas? ive checked connections, fuses, grounds...

[A34D4ME]

Short circuit - check amperage draw on alternator.

[Exille]

Great! i think i fixed it! i found more ragged wiring and pulled it all out, removed the garbage cd player and crimped on a new ring connector to the alt output, battery is showing 14v now