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Spiffing up my new (2me) Nikko Alpha 230 Power Amp

w1jim

w1jim

I can fix it but good...
Subscriber
Finally, an upgrade.
When I got out of college I picked up a Nikko Alpha 220, Beta 20 preamp and a Gamma 20 tuner. Well, through a local AKer I finally scored a nice Alpha 230, Beta 30 and Gamma 30 for the collection.

I did a few upgrades to the 230:

5-way binding posts
Recap the amplifier stages with Nichicon FG and Muse caps (didn't do the protection, display or regulator circuits)
Replaced the 2 - 1uf bipolar input capacitors tied to the Direct/Normal switch at the RCA jacks with a pair of Nichicon Muse caps. Also repalced the 1k carbon film resistors with 1% metal film parts
Upgrade the opamp from a 6552 to an OPA2134 (fet - and installed a socket)
Replaced the bulb for the meter scale
Cleaned the switches and PCB crud
Adjusted the idle current to 18mv

The opamp amp upgrade is probably not entirely necessary since the opamp is used in the servo circuit that automatically adjust the bias to the power transistors.

The bulb replacemnt was slightly tricky as I didn't have a large 6 volt bulb with wire leads like the original.
I replaced it with a 6.3 volt bulb with a bayonette base and I soldered the wires to it then put heat shrink over it and held it in place with a little silicon sealent.




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Nice post!!
Looks like a beauty! I love the old Nikko gear... reminds me of Sansui-- built like tanks with that wonderful sound.
 
I found that upgrading the op amps in the preamp made a significant improvement.
We did some op amp comparisons at our 2014 New England winter GTG and the results were very well received.
 
I'm working on a NA-890 right now. It is just so impressive. There isn't one single part on the whole thing that doesn't exude quality. I almost feel guilty for talking my mother-in-law out of it. Almost.
 
I picked up an Alpha 230 last year in it's original box. Hooked it up and put the gas to it and it worked for about 5 minutes until I boofed the volume up more and then lights out. It went into the dumpster unfortunately. Only was out $20
 
I extensively fixed up a Nikko Alpha II and those things are beasts! I sold it for way too little on the bay and want it back now....
 
Northwinds said:
I picked up an Alpha 230 last year in it's original box. Hooked it up and put the gas to it and it worked for about 5 minutes until I boofed the volume up more and then lights out. It went into the dumpster unfortunately. Only was out $20
Click to expand...

:tears:
 
Nikko 230

Working on one myself.This one had multiple issues.First, the bridge rectifier
was causing the main fuse to blew as soon as u powered it up.Got that issue
fixed.Then i found 4 output transistors shorted.Waiting on the last one to
arrive so I can get them all installed.
 
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