On 27 Nov 2021, at 21:00, Gregory Beat via cctalk <cctalk at classiccmp.org> wrote: ?Al - The Texas Instruments (TI) 139 is likely a 2N139 PNP (BJT) transistor, capable of high speed switching (in that era). The 2N139 was originally an RCA transistor (tall cylinder) found in RCA and GE transistor radios (455 kHz IF section). The TI versions were low profile metal case, TO-33 case (8.5 to 9.5mm diameter) greg == From: Al <alsilisk at icloud.com> To: cctalk at classiccmp.org Subject: IBM transistor replacements Dear all, A while ago I received an IBM 3286 printer, annoyingly some of the transistors in the printer section have been corroded. What I am having trouble with is reading the part codes and finding a modern equivalent of them. One has a Ti logo and two sets of numbers (attached). Does anybody know which numbers are the part numbers and if they are IBM house numbered? Photos of the Ti transistors and card assembly: https://drive.google.com/drive/folders/1JTnsWS4A8NrYJNFsqK2ejOeqqJNjoF1w?us… Thanks in advance, Al

On 2021-Nov-27, at 11:22 AM, Gregory Beat via cctalk wrote: From the JEDEC number, 2N139 would be a 50s-era transistor, way earlier than the ones at issue. 2N139 specs are Ge-PNP, 16V/12V CE max, 15mA IC max, 35mW max, which can find a use in transistor radios, but highly unlikely to be what the OP is looking for.