hifi engine





jjcb1953's picture

Re: NEC A-7

A little late but...
Dust is a very good insulator and only a millimeter blanket of it can cause amplifiers that run in Class A at lower volumes, to literally cook themselves to death. That is likely part of the problem with your A-7 and fiddling about will likely not lead to a successful conclusion. I'd recommend getting some electronics professional to take charge. Is it worth that? I can say 'yes' it is.

NEC, the Nippon Electrical Company, made some first class hifi components from the get-go and the A7 is one of them. I've owned an A7 for quite some time after spending a grand total of $250 including professional cleaning, parts replacement and re-biasing and am pleased enough with the result that it splits duty with a 2014 Bryston B60R SST Integrated amp costing 7x as much and does not suffer by very much at all in comparison.
If you peek under the hood of one of the top rated so-called 'vintage' components from Sansui, Pioneer, Marantz, Nakamichi, Akai and Onkyo they are likely filled with a slough of electronics made by NEC and other parts giants such as Mitsubishi, Toshiba, Sanyo and Hitachi. These giants of the parts industry were capable of producing very fine gear and most of it was as good or better than that put out by the favored brands - most of which were incapable of manufacturing the electronic parts they relied on.
Its worth noting that when hifi companies started their now infamous 'race to the bottom' during the mid 1980s almost all of the Japanese electrical parts giants stopped making hifi components and moved towards making computers instead.

I can heartily recommend NEC hifi components prior to 1985 as the integrated amps, tuners and CD players I own are first rate products with big power supplies and the best innards NEC was able to make. My units have far more metal than most at that time and are very reliable, heavy duty performers. However I have no experience with NEC's surround sound or home theater units so I cannot speak to the quality of gear from that era but can well imagine that even with the huge rise in the use of plastics and the reality of 'price point manufacturing', NEC would still have made a decent product compared to many others.

Re: NEC A-7

I'm also late to this conversation, but I just recently came into possession of an A-7. It's practically mint condition, but I need to know the specs for setting the bias (among other things I could glean).

Any chance you have an electronic copy (i.e. scanned-in) of the A-7 service manual? Or the owner's manual? I've scoured the web, but this is a pretty rare amp. So, documentation seems to be unobtanium.

Re: NEC A-7

Hi All;

I've got one of these, and it works BUT one channel is very low compared to the others.

Any clue?

Also, the power switch lamp indicator doesn't work. I measured the voltage across it's terminals and it appears to be NO voltage whatsoever. any hints?

Cheers, Stefano.

P.S.: when I've got it it was filled with dust and dirt, as in few mm deep, components were barely visible. Of course I cleaned it thoroughly before powering it on.