Hi Wayne, I did measure the mosfet cases to the heat sinks. The good channel readings were exactly the same. I took a leap of faith today and installed the suspected bad mosfets on the working channel and all was well on the outputs = 0vdc ..and then took it a step further and played music thru the channel so the problem is on th driver board and i can eliminate the idea that i have bad mosfets. heres a picture of the switched mosfets ..the installed mosfets were the one on the side of the driver board that was not working.....question? what would happen if i were to loose rail voltage on 1 of the sides of the circuit under load.
Attachments
Q9 BASE=1.20VDC Q12 BASE= -0.45VDC the output your talking about is the pos speaker terminal of that channel correct?
Q9 BASE=1.20VDC Q10 BASE= -0.45VDC reading is not right
please measure the voltage between Base pins of Q9 and Q12
please measure the voltage between Base pins of Q9 and Q12
Patrick, i dont know if you got the message but i did swap the mosfets to the other side of the driver board and i played music ..the dc offset was 0 volts ...so all my mosfets are good.
Patrick , the readings i gave are correct for the defective channel ...........i measured the good channel to compare and the readings are Q9 BASE =1.11VDC AND Q12 BASE =-0.56VDC
all mosfets are installed on both channels ..the amplifier is completely assembled with the exception of the input jacks..the reading were taken from the connections going straight from the driver board
ok, both channel voltage reading is very close and seems they both are working ok
Q9 Base to ground=67.6vdc Q12 base to ground=65.8vdc this is channel 2 the bad channel. Q9 Base to ground=1.12vdc Q12 base to ground=0.56vdc this is channel 1 the good channel
