Among quite a bit of other wisdom, Tony wrote: Ah, the pot 'o gold at the end of the rainbow! A skilled repairman, who works for pinouts.... :-) More seriously, while I aspire to fix things like Tony, I find that ignorance and lack of time are powerful disincentives. (The little one needs his diapers (nappies?) changed, and the bigger little one is gonna be going to college in about 10 years, so I gotta earn tuition, and then there's paying for the classic computer shed that the wife insists on filling with "nice furniture" and "decorating" because she thinks of it as a "house"....) I can swap modules. When I click the switch and nothing at all happens, and I have a new power supply on hand .... it's within my limited time and knowledge horizons to swap 'em. Getting an o-scope, learning how to use it, taking apart the power supply (and trusting that the little one won't ingest some of the nuts and washers while the medium-size one is getting a talking-to about sliding down the bannister with the power cord in tow).... well, that may be without my horizons. All this ranting leads to my question, to the group as a whole and Tony in particular: Is there a way I tell that it'll be safe to board-swap? In other words, are there symptoms I can in general use to tell me that the fault that caused damage was on the damaged (e.g.) board, and that therefore, if I have another example of that board, I won't fry it too by putting it into the place of the damaged one? - Mark