Dear Friends,
A friend gave me a Technics SU8044 to repair. I noticed that both the power ICs (STK0039) have blown. I replaced both the ICs. Our mains voltage is 240 volts AC, I am using a Variac. I set the voltage at 100volts AC and switched "ON" the amplifier. The amp works perfectly well. Now as I turned up the AC voltage slowly, I noticed that at around 150 volts AC, the sound becomes intermittent. It comes on for a few seconds then goes off for a few seconds, and it keeps repeating this. As I turn the voltage even higher, the ON and OFF period gets even longer. When I set at 240 volts, the sound doesn't come on. If I reduce the voltage to 150 to 80 volts AC, It works fine. Can someone please give me a clue what can be wrong.
Thanks
Carlos Rajoo
Dear Carlos,
You replace an original STKxxxx or STKxxxx/II? If you use the II you need to see the ic's schematic diagram. If not works change the power supply's capacitors to 10000uF 63V.
0
Thank you friend, I will try that.
Carlos
0