Re: HP 140B LVPS -12.6V Not Working
|
Something about this is confusing me.? Looking at the board, the transistors and diodes all have a dot at one lead.? I was thinking that dot indicated the emitter and for some transistors, that holds.? It agrees with the 2n3409 I replaced and most of the metal-hat transistors.? With the flat of the 2n3904's TO92 facing me, left to right is EBC.? For Q484, though, the diode across BE (I can't read it very well but I think that's CR485 or CR486) is connected to the center lead and the right-hand lead (facing the transistor's flat).? Do those not follow the same convention as, say, a 2n3904?? I'm used to either EBC being left-to-right facing the flat or, possibly, B on the left or right, but this is puzzling to me.
Thanks again, Barry - N4BUQ
With the different variants of the 4-071 you need to make sure the leads are in the right configuration, one of the old 4-071 variants has leads formed to get the base in the middle. TI is Texas Instruments, the 001 is a date/batch code, the Motorola ones usually have EBC marked on them.
David
|
