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NAD 7020 E

R

razwanzel

New Member
Hello!
I just signed up here, i found a lot of help regarding my newly acquired vintage NAD 7020 E.
I do know my way around electronics a bit, but i have a strange problem with my amp.
When i got it, sold as defect, i hooked up a multimeter to the output and found i have 2,86 volts on both terminals.
I downloaded the manual and started searching, only to find out that there were some alterations made.
The manual tells you how to set de quiescent voltage with 2 potmeters, but when i tried that, there was no change at all!
also most of the voltages on the print are of, and nothing i do has any effect!.
there are also extra resisters on the bottom of the print, in parallel with the output coil, end the schematic calls for 2 1k2 resistors, where the factory install is 1 of 150 Ohms, this is the resistor connected to the center voltage resistor.
I did not yet hook up any speakers for i do not want to blow the up, the voltages feeding the circuit are all oke, and nothing gets warm or smells...
I'm at a lost, anyone can help me?
 
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Moving to solid state from tuners. Clearly not a problem with the radio section.
 
Well, I've been checking the voltages, components etc.etc.
What i found thus far is a blown resistor in the +48 to 41 circuit, the BD139 which was fed by the resistor was bad.
temporarily replaced them and checked, now i can adjust the bias to 0!
ordered the parts...
result will follow!
 
you're right!
i meant the voltage to the speakers.
that should be 0, but whatever i did, it got stuck on 2.86 volts, both channels
 
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