Tony, I have a service manual and parts list for the 9100, I'll try to help. At 10:53 PM 12/21/98 +0000, you wrote: Do you mean the -3500 Volt power supply board (pn 09100-66522)? That's the board with the large transformer on it and the focus and intensity controls. is short-circut all ways round. HP says "Q1 -- 1854-0322 -- Quantity 1 --- TSTR: NPN, Si --- (Mfr) 86658 --- obd" The notes say that "obd" means "order by description". There's a list of manufacturer's code in the manual but 86658 isn't listed. ??? I think those are standard codes, you may be able to look it up elsewhere. I don't see any other usage for that transitor anywhere else in the 9100 but from the looks of the circuit, I doubt it's critical. There's a good theory of operation description of this circuit in the manual. Let me know if you need a copy. Joe

Tony Duell wrote: A friend who works for HP looked it up in their database, and emailed me the following information: 1854-0322, Silicon Power NPN TO-8 can transistor, IC = 2.5 A max PD = 25W max at TC Electrical: BVCEQ = 40 V min HFE = 20 min to 100 max at IC=300 MA VCE(SAT) = 12.5 V max at IC = 2.5 A Suppliers were listed as RCS, Harris and GECO (General Electric I think). Maybe this will be enough data to figure out a good replacement. Hope this helps! BTW, at 25 W max power dissipation, I'd make sure there was a heat sink on the TO-8 can! These specs do sound pretty similar to a 2N1701. The TO-8 case is apparently similar to the TO-5 case but larger. 'RCS' was probably supposed to be RCA, since RCA did make the 2N1701. It's unfortunate that he was not able to get the vendor part numbers, but I doubt that the original parts are still made. Motorola claims that the replacment for a 2N1701 is a 2N4910, which is in a TO-66 case (like a TO-3, only smaller). Unfortunately this is not a good mechanical replacement for the TO-8. Searching for 2N1701 with Altavista revealed several companies that may stock them. Rich suggests that you might also consider the MJE340. But the pinout is in the wrong order as compared to the 2N1701. Cheers, Eric