cctech Digest, Vol 104, Issue 21 - test-drb@ccmp.vtda.org

11 Apr 2012

 On Wed, 11 Apr 2012 09:23:49 +0100, "Rob Jarratt"
 <robert.jarratt at ntlworld.com> wrote:
...

 I need to replace a transistor in my H7140 PSU for my PDP11/24. The
 transistor is marked GPSA55J3 and the printset identifies it as "XA
 55 PNP
 500MW SI 60 50 P", it is in a TO-92 package. I have tried to find
 specs for
 an A55 and can only find partial matches, so I am not sure what
 today's
 equivalent would be. Can anyone help me work out what the equivalent
 today
 would be?
 Thanks
 Rob 
 Sounds like a 60V, 500mW device. BC556, MPSA-56. A BC161 might also
 work, except it is in a TO-39 case, or a 2N2907 in a TO-18 case.
 Looking at the printset on vt100.net, none of the A55 transistors
 appear to be doing anything terribly demanding, so any of the above
 ought to work.
 /Jonas