Q1 and Q2 are part of the oscillator circuit. They are both identical 2N4258 PNP transistors according to my CPU board schematic.
-Blair On May 3, 2013, at 5:09 PM, Hardware Mack wrote: > thank you for that great information! > > Can anyone look at their lisa cpu board and let me know what you have in that > spot? > > Thank You! > Charles > > > > On May 3, 2013, at 6:01 PM, Doug McNutt wrote: > >> At 12:56 -0700 5/3/13, Notgoing Totellyou wrote: >>> I have the CPU card here and its missing a transistor. >>> >>> i can't find a replacement anywhere. >>> >>> Anyone have any lisa parts laying around? >>> >>> it reads : AMPS 4258 EBC >>> >>> you can see the spot behind it, it's missing . >>> >> \ >> Transistor Data Book edition 48, 1980 >> >> MPS4258 CRI, SPS, MOTO p 153 line 15 which says: >> >> Silicon PNP low power >> 350 mw collector dissipation >> V cbo 12 V >> Collector max 800 mA >> Hfe (gain) 15 >> >> >> I would recommend a very common 2N2907 as a replacement. >> >> From the picture it's not altogether clear that transistors Q1 and Q2 are >> supposed to be the same type.. A pretty common circuit uses PNP and NPN >> pairs close together. The pair to the 2N2907 is NPN type 2N2222, also very >> common. (I have a bunch of both here. Use dmcnutt at above off list with >> Lisa somewhere in the subject.) >> >> A look at a working Lisa would be worth while. Anybody here ?? >> >> I also have no idea what the A in front of the very common Motorola MPS >> means. >> >> >> -- >> >> Fe++ >> // \ >> Fe++ Fe++ >> | || >> Fe++ Fe++ >> \\ / >> Fe++ >> >> -- >> -- >> ----- >> You received this message because you are a member of the Vintage Macs group. >> The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our >> netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml >> To post to this group, send email to [email protected] >> To leave this group, send email to [email protected] >> For more options, visit this group at >> http://groups.google.com/group/vintage-macs >> >> Support for older Macs: http://lowendmac.com/services/ >> --- >> You received this message because you are subscribed to the Google Groups >> "Vintage Macs" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> > > -- > -- > ----- > You received this message because you are a member of the Vintage Macs group. > The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our > netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml > To post to this group, send email to [email protected] > To leave this group, send email to [email protected] > For more options, visit this group at > http://groups.google.com/group/vintage-macs > > Support for older Macs: http://lowendmac.com/services/ > --- > You received this message because you are subscribed to the Google Groups > "Vintage Macs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. > > -- -- ----- You received this message because you are a member of the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To leave this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/ --- You received this message because you are subscribed to the Google Groups "Vintage Macs" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
