hi everyone, this is continuation of thread that I started in year 2009! when I first posted about this receiver and then let this receiver aside in my basement and after all these years have only now! find time to work on it again, does any mcintosh expert know why it keeps blowing 5 a fuses?! checking the power supply with a digital meter shows that dc voltage after the 600ohms 5 watt resistence shows 150vdc instead of the schematic reading of 110v dc, also one one of the driver board all the group of three transistor show defective replacing these , a diode and all new electrylitc capacitor on the board did not solve the problem, also like to mention have replaced the 9000 uf /50v electrolytic and one of the multi sec capacitor 80/80/50 uf , the pre-amp section is working great, the am is working too, there is no sound from fm wonder why the signal strength meter show tuned station but no audio, and lastly there is problem with balance control when you move it in the center the audio disappear but when you move it to extreme left or right the audio for that channel appear , I have the service manual, any kind help by resident experts here will be much appreciated, thanks! Ali
the other driver board where the parts are all original and not replaced the transistors get so hot you can see smoke rising all this happens powering with a variac at only 40-60 volts, the other voltages like -40 and + 40 dc are correct the smaller voltages from power supply seem o be correct as the light light up well in the panel, the pre amp section is working, as is the line input and the am section,but no sound from the fm section, this was verified using the pre-amp out jacks connected to a Nad integrated amp aux input and listing to the sound via nad stereo headphone socket
the other driver board where the parts are all original and not replaced the transistors get so hot you can see smoke rising all this happens powering with a variac at only 40-60 volts, the other voltages like -40 and + 40 dc are correct the smaller voltages from power supply seem o be correct as the light light up well in the panel, the pre amp section is working, as is the line input and the am section,but no sound from the fm section, this was verified using the pre-amp out jacks connected to a Nad integrated amp aux input and listing to the sound via nad stereo headphone socket
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