On 4/18/23 09:40, Tony Duell via cctalk wrote: > On Tue, Apr 18, 2023 at 2:51 PM Tom Hunter via cctalk > <cctalk@classiccmp.org> wrote: >> >> The blown out resistor likely has "blown out" for a reason. >> The replacement will probably suffer the same faith unless you find the >> root cause. > > > As soon as I saw 'Boschert' mental alarm bells triggered.... > > Boschert made a particularly unfriendly (to the repairer) type of > SMPSU which I call the '2 stage'. I can explain how it works if > necessary, but be warned that with one of those if a particular power > transistor fails (and it often does), it takes out a couple of other > power transistors, the current sense resistor, numerous small > transistors, the regulator chip, the fuse and sometime PCB tracks.
True, but Bob Boschert was a pioneer in the field working with what components were available. So don't be too hard on him. --Chuck
