Hi,
I’m making the start up of the audio amplifier K8060. When I was adjusting the bias currrent, after some minutes turned on, I noticed that transistor T3 reached a quite high temperature. The amplifier works well, I connected the speaker and I played some music and it sounded OK, but I’m worried about this transistor could get burnt or even went off…
The power supply is 30Vac (symmetrical) and I get a DC voltage level of +/-42Vdc in idle state.
is it normal?
‘A quite high temperature’ is kind of subjective.
Can you measure the exact temperature?
Up to about 60°C, it should not be a problem.
As for the power supply, 30VAC is the absolute maximum.
It should result in approx 41VDC.
I measured the temperature on the surface of the transistor with a bulb thermometer an it reaches 53ºC (ambient temperature 25-26ºC).
Perhaps the measurement wasn’t very accurate, but, as you say, is more objective, so I think the circuit is working properly.
Thank you very much for your assistance.
Kind regards,