#2n3906 transistor substitute for 2n1307 how to

That current becomes a voltage across the 560 ohm between base of T604 and the thick black Ground buss. That (error) current exits the collector. The difference of Vbase and Vspeaker becomes a current across the 820 ohm between speaker and emitter. The T601 is where the input signal ( from Preamp ) is subtracted from the feedback signal to the loudspeaker. Schematic- T601 is the one that needs replacing: If not, there are some random parts I groused up on Mouser based on the filters that seem like they might be appropriate, but I'm for those I'm casting around in the dark a bit. I'm not knowledgeable enough to look at the circuit and see why the schematic shows the BC158 and the actual part used was a BC158B- they appear to be likely different in amplification function, but maybe (presumably?) it doesn't matter here.Ĭan anyone offer a theory for why the original part used could be a higher-gain model without messing anything up?ĭo I need to seek out a higher-gain replacement part? I'll use a 2N3906 if it would seem to work. It appears to me that a standard general purpose 2N3906 would seem appropriate relative to the base BC158 (has same or higher max voltage, higher max current, and similar hFE.

#2n3906 transistor substitute for 2n1307 how to

I have asked before here and gotten good advice on how to think about transistor equivalence in audio when going from vintage euro parts to current US replacements. Here's a datasheet showing the BC158 series. The only difference between the BC158 and the B variant is the hFE gain value (higher value in the B).

(Schematic with highlight is below.) The part on the actual board is a BC158B the schematic specifies only 'BC158'. I have identified a failed (shorted) PNP transistor in the power amp section.

On a long but educational process repairing a vintage German stereo.