NAD 3020 with hum, $40 - worth it?

[filmis]

Hello all,

An NAD 3020 popped up on my local CL for $40. It has a hum (audible through the speakers), but I can't go listen to it before I purchase it...

It is also missing a plastic cap on one of the buttons but otherwise appears to be in good condition.

What do you think, fellas? Worth it? Can I get him down to $30 maybe given the defects?

Also - I have a Technics SU-G90, is it a good idea to use the NAD 3020 as a preamp for it? I know the NAD has a much lower THD than the Technics (0.02% compared with ~0.9%), so would this effectively make connecting the NAD to it pointless?

 

[bradfro]

Yes, 40 is a good price, but it's going to need a recap on it. ~$30.00 for new caps, a soldering iron and a solder sucker and some skills with soldering. It would cost significantly more to have someone do this work for you.

If the technics amp has a preout/amp in jumpers on the back, you can use the 3020 as a preamp. But the 3020 amp my sound better than the technics when repaired, it is only 20 watts per channel which my be an issue for you depending on the speakers you're driving.

 

[filmis]

Yes, 40 is a good price, but it's going to need a recap on it. ~$30.00 for new caps, a soldering iron and a solder sucker and some skills with soldering. It would cost significantly more to have someone do this work for you.

If the technics amp has a preout/amp in jumpers on the back, you can use the 3020 as a preamp. But the 3020 amp my sound better than the technics when repaired, it is only 20 watts per channel which my be an issue for you depending on the speakers you're driving.

I feel pretty comfortable soldering myself, so that's not a huge issue. What I'm worried about is if it's more than just the caps (e.g. a rectifier) which would complicate the job and be even more expensive to fix. But the seller says the sound is good except for the low hum, so maybe it's just the caps.

The speakers are 130W Sony SS-U380s, but I have a pair of 20W desktop speakers... Can't remember the model right now... that I can also drive with them.

 

[EVBoy]

You may just have to reverse the plug or try another outlet. It may also be something external. Hum is really rare on SS units.

 

[filmis]

I got him to part with it for $30. Hopefully once I get it it will turn out well!

 

[bob smog]

Probably nothing more than caps.

Cool looking amps, owned one about 20yrs ago.

 

[mtlmn1971]

Have one I found in the dumpster. Very nice sounding little amp.

 

[cgutz]

Have one I found in the dumpster. Very nice sounding little amp.

Unbelievable....

I almost bought one in late 70's. Bought the Sony Vfet TA4650 instead (dealer gave me a good deal, matched the price of the NAD for a refurbished.) Still have the Vfet, but also like the 3020 and have always wanted one to fall in my lap.

 

[northpaw]

FWIW, I bought a 7220PE (sort of a cousin to the 3020), also with a hum, for the cheap, and it turned out to be one bad cap on the PS for the higher voltage (+/-48V) rail (not the large main PS caps, but the somewhat smaller ones on the auxiliary PS for the PE circuit, a 330µF cap). That cap had visually degraded, either from leaking or corrosion from the glue. Once out, it tested as failed.

Hard to generalize, but a failed cap on the PS will give you hum, so it needs to be on the list of things to check; for me, it would be the first. A quick in situ test is to tack-solder, in parallel to the suspected cap, a similar value cap to the solder pads on the underside of the board, and start up (keep bottom cover off and unit on its side so you don't squash the hanging cap). If the cap on the board is bad, the hum will be much reduced, or gone.