sansui G7500

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trace59

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Joined 2007
#1
I am an experianced electronics technician. I ran a business for 7 years and worked for others for 10 years. I have been out of the swing of things for about 7 years. I recently have come across a Sansui G7500 that had the right channel shorted out and several parts(resisters( burned on the amplifier board. I have the schematic and it apears to be miss marked. I bought original outputs and they shorted as soon as I powered it up. I tried a second time with a variable ac supply and it shorted afetr about 40 VAC.

Now I have spent a lot of time on this and I am at a loss, I can find no obvious problem. I have noticed that the dc supplies +63 -63 volt supplies. won't go above 15 VDC, after reaching this voltage the current starts going up and the voltage starts going down. Do you have any ideas of what I am missing?
 
#7
the schematic you posted is barely readable sir, in the meantime you could check for some 'open' resistors' especially those low values (100 ohms and below) some tend to go open.

You mention on your previous post that upon power up the output blows instantly, an open bias ckt perhaps? open bias diode/bias transistor, loose trimpot
 
#8
I have checked all of the low ohm resister. I have also checked the bias Diode. I have the schematic on a 3.2m pdf and I can email it to with an address. I have not checked the trim pot. I will take another look at it this weekend.
 
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