Barn Find

[Disco Volante]

A friend dumped this on me. I don't HAVE to fix it, and he doesn't want it back, so we got nuffin to loose and evrding to win...
It's really very heavy. Made in Japan. 80's?
Let's see if we can get some rock'n roll out of this old dirty bastard. All else fails it could house my DIY nuclear power plant.

 

[rock soderstrom]

Cool, put this amp in dishwasher!

 

[CJ]

Nice!

from audiokharma>

I just restored one of these. I own the "set" with matching preamp, tuner, EQ, and cassette. Note the output transistors are obsolete and long out of production. They are high-speed and nothing matches them made today as replacements without serious retrofitting (and cost). You would be wise to have a qualified tech take a look at it and run it through it's paces. These are a high-speed design, run warm, and are similar to the Pioneer NSA amps and sound awesome once restored. Make sure you have nothing to block air flow on the top. They get quite warm when cranked up. If it hasn't been recapped, the old electrolytic caps are ticking time bombs and many will be dried out from the heat these produce. Plus old electrolytic caps in the signal path seriously degrade the sound.

 

[k brown]

Hard to tell from pic - is it as dirty inside as outside?

 

[Tubetec]

When you say you dont have to fix it , do you mean its working ?
it could very well be under the layer of grunge and oxide ,
definately worth evaluation , even if it doesnt work , maybe its an easy fix ,
Looks like a decent 100WPC Japanese Hifi amp from the late 70's or early 80's ,way before my time in the hifi trade.

 

[k brown]

https://www.hifiengine.com/manual_library/nikko/alpha-220.shtml

(contains Service Manual)

 

[Disco Volante]

Yes, it is very dirty on the inside too, I'll take some pictures as I go...
I mean it's not a commisioned fix, just a for-fun project.
Most definitely a recap and a thorough clean-up coming up. Might be a pair of LED VU meters under there...

Legend has it bi-amping a huge pair of Cerwin-Vegas together with the Technics SA-700 which is now also sitting in my small lab, equally dirty and with a black painted faceplate...

 

[Disco Volante]

Soapy suds, then a blast with the powerwasher. Now drying out on the radiator..

 

[rock soderstrom]

I can't wait to see what's broken, I'm sure you'll get it running again! Keep us up to date

 

[Disco Volante]

The amount of gunk in those cooling fins...
I downloaded the service manual. It is the most amazingly thorough manual. Even has datasheets on all semiconductors!
Anyway, it looks like a fairly simple recap-job now that all the gunk is gone, and then set the bias.

Some danish dude on hifiengine seemed to have gotten good results with upping the bias-current and replacing some noisy resistors. I'll start with a recap and see if I can get sound before I start modding!

Not sure what to make of the "variable bias circuit". Time will show whether it's a keeper or a doorstopper or a very heavy fleabay item (too many of those floating around me!)

I'll keep you posted;-)

 

[Disco Volante]

A few pics shot today. Sunshine finally.
Don't see any nasty tants, but the component list mentions a few BP caps...

 

[Script]

Nice. Nikko ? In Japanese can mean 'sunshine'.

 

[iomegaman]

I got a Nikko Alpha I at the surplus store here for $180 spent a couple of months trouble shooting (the left channel kept blowing transistors)...it got kind of expensive be ause those old power transistors are hard to come by and not really cheap...when I finally did get it running it was awesome...I ended up a huge Nikko fan and picked up a Nikko Alpha III which now powers my NS10's...

I still have the Alpha 1 but got tired of throwing transistors into the left channel so its still on the bench...it takes a while to get those old OEM power transistors from Japan and can get pricey if there's no real reason why its popping them.

These things are built like actual Sherman Tanks...

My brief study of them found that Nikko made some kind of switch/relay and were pretty well the dominant market company in that category, the owner had a daughter and her husband wanted to start building audio gear to compete with Sansui/etc...so the father let his SOL run it...everything was top notch quality and built only in Japan...so they really couldn't compete price-wise...this old Nikko stuff is almost always worth the trouble and sounds fantastic.

 

[Ike Zimbel]

A few pics shot today. Sunshine finally.
Don't see any nasty tants, but the component list mentions a few BP caps...
View attachment 122627View attachment 122628View attachment 122629

I'd be very surprised if any of those electrolytic caps are out of spec. Most Japanese caps that I've seen of that vintage have measured perfectly. Just FYI.

 

[cyrano]

That's a keeper!

It's one of the better sounding amps that I ever had.

 

[Disco Volante]

.when I finally did get it running it was awesome...

How did you get it going? Is there some oscillation killing the transes? or the "variable bias" going off on a trajectory?

Maybe I'll just let it dry for bit longer and power it up? I'm going to have good look and see if anything looks dodgy. No burnt traces or anything so far.

Thanks for your kind words, now I'm almost excited to hear this old dame shake down the workshop..

 

[k brown]

I would suggest running around inside with some gentle compressed air. Water trapped in tight places can take quite awhile to evaporate completely.

 

[iomegaman]

One of the things I've done with old questionable gear is do a quick bath in 99% Isopropyl Alcohol and heat gun to dry...use a toothbrush and any questionable parts dry quickly...

As far as getting my Nikko to run the units I have used the NEC 2SB600/2SD555 TO-3's which are like 15amp 200 watt transistors (6 each of them each) ...so that will explain the copious heat sinks...these things get REALLY hot...Nikko did not mess around with under powering anything...everything was pretty hefty wattage (at least the stuff I have)...so making sure those transistors are getting adequate heat transfer is kinda important especially after sitting for that long.

I need to revisit why I kept blowing transistors on the left channel, there are other obscure transistors used to control the voltage maybe 4 on each channel and very old zener diodes with specific call outs that were kinda hard to source...

Find a manual if you can...it will save you lots of trouble.

 

[cyrano]

Gear like this goes in the bath tub with the cover off, gets washed with hot water and some soap. After that, I rinse it a number of times with tap water, until there's no visible debris left. Sometimes it needs a repeat wash with hot water and soap if very dirty.

The last rinse is with demineralised water. I sometimes add up to 5% alcohol (for smoked gear). Using pure alcohol is faster, but too expensive, as the kind of gear that's this dirty usually isn't worth that much. Besides, I'm cheap.

This obviously needs to dry out for weeks. I've seen short circuits due to debris that wasn't removed, but none due to moisture. Most of the gear I've treated like this, came from discotheques or bars in an era that smoking still was allowed in those. One set had spent over six months in a house boat on the bottom of a canal.

 

[Disco Volante]

Blew it out today with superdry air from the neighbor's fancy-compressor. Also cleaned the massive 6mm aluminium front-piece. Smoke gets really hard stuck on things like speakers and amps. That front panel took several rounds with dishwashing detergent and a soft sponge.
The power switch needed a little "electronic cleaner" spray to move properly.
I'll take some pictures tomorrow and also give it a slow ramp-up on the variac to see if Ike is right and those old caps still work...