The screenshots you posted state a minimum value of 160 for hFE, not 180.
The hFE range is unusually narrow, 160 to 200 at 1 mA and 10 V.
The hFE range is unusually narrow, 160 to 200 at 1 mA and 10 V.
The amp had an HS channel and a power transistor had failed. The OD-503 power transistors are in fact 2sa1065 and 2sc2489 transistors in a new package, I undertook a total restoration of this amp because it was poorly stored and therefore the chassis was slightly rusty. At the same time I take the opportunity to replace the capacitors inside and check if everything is on the cards. That's it would bother me to replace transistors for nothing especially since they are rare and unavailable everywhere but as the datasheet of these transistors is not available I have doubts about those. I don't think it's normal for a transistor not to be in the original specifications, hence my question here, I repair quite a few amps and this is the first time I'm faced with this. I have a stock of 2sa1306-B and 2sc3298-B it could be a good replacement but if I can leave it as original that would be better. Sincerely
Thanks 🙂
Its a valid question that you ask and without me having a specific answer as to why you get the results you do for hFE I would just say is it likely or logical that all would be outside the range you expect? Transistors do not deteriorate or fail in this way.
Why not rig one up across a 9 v battery and do your own hFE test at say 1ma, 5ma and 10ma and see what the gain calculates out to.
Its a valid question that you ask and without me having a specific answer as to why you get the results you do for hFE I would just say is it likely or logical that all would be outside the range you expect? Transistors do not deteriorate or fail in this way.
Why not rig one up across a 9 v battery and do your own hFE test at say 1ma, 5ma and 10ma and see what the gain calculates out to.