12 Nov
2005
12 Nov
'05
1:33 a.m.
At 01:26 PM 11/11/05 -0800, Brent wrote:
>David Comley wrote:
>>
>> I have been trying on and off for a while to map out
>> the schematic for the PSU of an HP7908 disc/tape unit.
>> There's a transistor I can't identify on the board and
>> I am wondering whether anyone can ID this thing for
>> me. The markings show "239" and then the batwings, and
>> then below that it says "4-456". Same problem for a
4-456 is almost certainly an abreviated HP house code. The full version
would be 1854-0456. From that first part of that (1854), it's almost
certainly a silicon NPN device (1853 would be silicon PNP, 1855 an FET,
1850 germanium PNP and 1851 germanium NPN, I think).
Amazingly it's in the equivalents list I have. It crosses to a TIP41A.
Would that make sense?
-tony