VAX-11/750 power supplies

Mattis Lind mattislind at
Wed Apr 8 01:50:19 CDT 2015

I am working on the H7104 power supplies for the VAX-11/750 now. The 5V had
a short circuit main switch transistor and a output rectifier diode that
also was a short circuit. Now it works fine into a 0.5 ohm dummy load.

Then when checking the 2.5V supply it had two out of three output
rectifiers short circuited.

So what is it with these rectifiers? They are Unitrode USD5096F but
unfortunately I cannot find any data sheet for them. I asked in another
forum and someone even checked the Unitrode data book for 84-85 but didn't
find the part!

However looking in the print set the diode is listed as 1114197-00 with the

Is the Unitrode USD5096F a 60 Amp diode? This link tells me it is a 35A
and so does this link:

Is there anyone that can enlighten me here? Is USD509F a 35 Amp part and
then why have DEC used parts that is not as specified in the print set?


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