The quick versions : Does anyone know of a book or website which gives brief characteristics of zemer diodes? The ones we use in Europe tend to have the zener voltage given as a suffix to the part number, but the US ones have 1Nxxxx numbers which tell me very little. The actual device I am looking for info on is a 1N5365 , but knowing where to look in future would be useful. The long version : I've got an HP2631 printer (wide carriage dot matrix with an HPIB interface). When I extracted it from my junk pile, it gave a power-on error (according to the service manual on hpmuseum.net) that was a RAM error. After pulling the case and CPU board, I was amused to see the RAMs were our old friends, 2114s. So I desoldered the RAM that the error code said had failed and fitted a new one. Next time I ppowered on, all hell broke loose. The carriage rammed into the right side plate and the carriage motor breaker tripped. Then the 2 fuses on the PSU board for the +/-20V rails blew, and the status LEDs for the +/-12V regulated supply rails went out. THe last is not too suprising, those rails are regualted down from the 20V ones. Replacement fuses blew at swtich-on Quick checks have indicated that both carriage motor drive transsitors (a 2N5844 and a 2N5886) are shorted all ways round. So is the overvoltage protection zneer between the -20V line and ground -- this is the 1N5365 I mentioned. I obviosuly need to replace these parts -- after finding out what caused the transistors to fail. -tony