8 Apr
2015
8 Apr
'15
1:23 p.m.
BTW. The same type of diodes are supposed to be found in H7140 PSU of the
PDP-11/44. If anyone out there has a 11/44 and is able to confirm what
diodes are used in that one it would be interesting.
2015-04-08 21:37 GMT+02:00 Mattis Lind <mattislind at gmail.com>:
2015-04-08 18:46 GMT+02:00 tony duell <ard at p850ug1.demon.co.uk>:
The problem I have it is impossible to confirm what the rating is for this
diode. I simply cannot find the data sheet.
The 5V PSU uses four of these diodes and the max output is 135A. The 2.5V
PSU uses three diodes and the max output is 85A.
However
looking in the print set the diode is listed as 1114197-00 with
the
remark "60 AMP POWER SCHOTTKY DIODE"
Is the Unitrode USD5096F a 60 Amp diode? This link tells me it is a 35A
diode:
http://www.electronicsurplus.com/unitrode-usd5096f-diode-35amp-35v-piv
and so does this link:
http://www.ebay.com/itm/35-Amp-35-Volt-Stud-Mounted-Diode-with-Wire-and-Lug…
/271653646843?pt=LH_DefaultDomain_0&hash=item3f3fd1b1fb
It's possible (although unlikely) that DEC selected diodes that could
stand 60A for this location from what were
nominally 35A parts. More likely, I think, is that what is _needed_ here
is a 35A diode (what is the output current
of this PSU) and that the originially specified part was a 60A one (which
is clearly be OK). Then somebody found
a 35A part that would work.
Of course you can always fit a higher current diode than is strictly
required (provide the switching times are
fast enough in a circuit like this). My guess is that since diodes have
improved since the days of the 11/750,
you could fit modern 60A Schottky diodes without problems.
I will try to run it with the replacement USD5096F that I have and see how
long it lasts. It probably depends on how many boards I stuff into the
machine. If that fails I will search for DO5 mount 60A Schottky diodes. If
anyone has a bunch of them at a good price I am interested!
-tony
/Mattis