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Technics SU8044

 
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Carlosraj7



Joined: 12 Feb 2013
Posts: 5

PostPosted: Tue Feb 12, 2013 12:55 pm    Post subject: Technics SU8044 Reply with quote

Dear Friends,

I am a new member to this forum, please help me with this problem. 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
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vtech



Joined: 08 May 2006
Posts: 1264
Location: USA

PostPosted: Tue Feb 12, 2013 11:38 pm    Post subject: Reply with quote

Sure sounds like it is set to run at 120V AC? Are you sure it is set for 220~240? Does it happen to have a voltage selector in the back? what is the ratings on the label on the back of the unit?
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Carlosraj7



Joined: 12 Feb 2013
Posts: 5

PostPosted: Wed Feb 13, 2013 11:21 am    Post subject: Technics SU8044 Reply with quote

vtech wrote:
Sure sounds like it is set to run at 120V AC? Are you sure it is set for 220~240? Does it happen to have a voltage selector in the back? what is the ratings on the label on the back of the unit?


It is set to operate at 240 volts AC, because that is the mains voltage in our country.
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