NAD 3020 Rebuild

The 3020 when it first showed up at our doorstep

          The classic (some would say legendary) NAD 3020. This particular example was bought second hand by the owner some time back and came with a few issues. Apparently it had no power LED and there was a slight hum from the speakers when in operation. Well, the hum grew into a massive hum and the owner finally decided to do something about it so he sent it to us.

          A quick visual inspection of the inside showed that the power LED was still there but had become detached from the front panel. The main filter capacitors had been changed to some unbranded ones and the output transistors were also not original. Fuses had been changed to fast blow types instead of the original slow blow fuses. As for the rear of the NAD, besides a layer of dirt and crud, everything looked as it should.

These transistors would have worked in place 

of the  originals, the only problem was that we 

suspected that they were fake.

Fast blow fuses in place of slow blow ones. 

Power LED detached from front panel.

PCB tracks for the output transistors had

been previously damaged.

Tear down

 The 3020's board was removed from its chassis 
and given a good clean.

Output transistors were removed and their 
heatsink was removed for cleaning. All of the old
thermal paste was cleaned off so that the new 
transistors would seat perfectly.

 All switches were cleaned.

Pots were cleaned as well and all found to be 

functioning well.

Assembly

The main filter caps were replaced with 

Panasonic FC caps. New STMicroelectronics

transistors were seated with new thermal 

paste and mica insulators. Bourns trimmers were 

also installed to adjust DC offset and bias.

The one mod that we had to do was to install

emitter resistors for the new transistors. This 

would prevent the amp from going into thermal 

runaway.

New fuses in place.

The amp also got a full recap with Panasonic

capacitors. 

Complete

 Almost done. 

          The 3020 was finally reassembled and turned on. Initial test showed everything to be fine so the bias and DC offset were set and the amp was put through the paces. 

          We had not heard the amp before as it was not operational when it first came in so we did not have anyway of knowing how good it was going to sound. We were pleasantly surprised because for a 30 year old amp, it sounded tight. Bass was there, clarity and not too harsh. No hum from the speakers. There was power on tap as well as we really couldn't go past 10 o'clock with the volume knob. All in all, it actually sounded amazing, no wonder these amps were so highly regarded and are still being sought after today.