Good morning friends, I tell you, I got an amplified speaker "15" RCA brand, JPS 2015D model is supposedly 300 watts RMS but the amplifier is 250 watts. the problem is that it came without audio, and when I checked I found that the horn is burned, because I have an impedance of 0 ohms, when it is 8, what I did was put a memory to set the amplifier with a smaller horn and the Burned again, it was then that I measured the audio output and had 50 volts positive, obviously I suspected the power transistors are four, two 2SA1943 and two 2SC52 but when removing them to check them the four are ok, also remove the transistors from the driver which are also four, two PNPs and two NPNs to see where the saturation came from, but everything was not found any anomaly, and now when mounting everything again in its place the output voltage has disappeared, and I didn't even change anything, and now the amplifier is working ok, with a smaller horn, because I need to repair yours ... I appreciate any comments and input you could give me to get out of my doubts ... greetings