VAX-11/750 power supplies

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>: > >>> 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. >> > 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. > > >> >> 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