Hello again! Yes, I did the tests with the multimeter measuring the resistor that is heating up, and its value is still within, no changes... also the transistor, it is in perfect condition... I'm back to square one... the accompanying sliders , rhythm, all of them, are working normally... no sound from the keys yet... mystery... without the specific electrical diagram for it, it gets very complicated, and the service manuals for other MTs are very confusing For me, apart from the fact that some components are on different boards, it is much more difficult to interpret.