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Nikko Aplha 650 needs help.

Rob41

Rob41

Don't stop believin'
Well I just managed to score a Nikko Alpha 650 on Ebay last night. It wasn't cheap even though it's stuck in protection mode but I've wanted one of these beauties for years.

I'll be recapping this amp but I want to repair the specific problem/problems associated with the protection.

I've searched for the schematics but I'm not finding them for this particular model.

If anyone here has the schematics, I'd really appreciate being able to get a copy.

The Nikko Alpha 650 is an amazing amp with 300 wpc into an 8ohm load and can be bridged for 650wpc...8ohm load mono.

They use seperate torroidal transformers for each channel and actually sound quite good especially with new electrolytics and proper bias settings.

Any help with schematics or other information would be great.

Here are a couple pictures of this beast::D

NikkoAlpha650.jpg



NikkoAlpha6502.jpg
 
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That's a beauty! I had a Nikko Alpha 450 a few years ago that wouldn't come out of protect mode. I checked the left and right input side of the protect relay and found no voltage present and no shorting south of the relay, so it had no reason to be in protect mode. I replaced all of the electrolytics on the protect board and it's been singing ever since (going on 3 years now over at my buddy's house). Nikko made some great stuff.
 
geez louise I hope you get yer manuals and get er fixed up Eh!

that's one sweet looking unit, I wish I could be of more help.

Shawn
 
Thanks. If I can't nail down any specific cause for protect mode I'll replace the electrolytics. I'm glad it got your amp up and running. These amps are a bit underrated but actually sound very good.

-Thanks for the link petehall347, but that's for a TRM 650 integrated amp which has very different internals.
 
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:lurk: Followed that auction - got past my price rang (but I'm cheap).Congratulations.
Be careful trouble shooting - High voltages and a slipped probe can release lots of magic smoke!
Tips for no relay - first need to check the amplifier outputs for DC (can be found at relay contacts, or at the emitter resistors) If more than a volt DC - that's where repair begins. If no DC, measure regulated voltages (schematic really necessary at this point). If okay, trouble shoot protection circuit. (I've tried to make it seem simple, but it usually isn't.) Good luck - a fine piece of equipment and should be worth it once you get it going. Steve
 
Thanks

Thanks for the kind words and tips. I will proceed cautiously and take my time on this one for sure.
 
Glad it went to an AK'er.
I had to drop out at $315.
Would have been the Admiral in the Nikko fleet.
Hope it gets going Ok. Enjoy.
 
Thanks Mr_B,
There are only so many of these kinds of amplifiers left these days and I couldn't bear to loose another one. This model listed for $1800 when new and I wonder what it would cost if they were manufactured today. I will get her up and running better than she was when new and post back here with the results.
 
I was following this one too. no intent at all , just lurking to see where the money wheel would stop for future reference. I've got an alpha 440 that's functional but could use some TLC ( Technical loving Care - cleaned - capped etc - which is not my area of expertise. Consumer? YES! Tech, no no no :) )

That Alpha 650 is absolutely bonkers! - . You might want to add that pic to the " who likes meters" thread. here: http://www.audiokarma.org/forums/showthread.php?t=394291

it certainly fits right in. :thmbsp:
 
Rob41 said:
Thanks. If I can't nail down any specific cause for protect mode I'll replace the electrolytics. I'm glad it got your amp up and running. These amps are a bit underrated but actually sound very good.

-Thanks for the link petehall347, but that's for a TRM 650 integrated amp which has very different internals.
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it looks like its not yet on the web not that i can find anyway ..maybe other search engines may find it ? i use google mainly .. if you can see through the pcb it shouldn't be too hard to draw the circuit ..
 
That is a real sweet look'n piece.Hope you can get the issues ironed out.:thmbsp:
 
Update

Alright, It's all better now. A transistor and a diode on the protection board were bad and it now works perfectly. I was expecting this amp to sound good and it does. It is definitely one of the better sounding amps I've heard for sure. So $4 dollars worth of parts and it's music to my ears. :D

Here are a couple pics of it in my current system:

SDC13991.jpg


SDC13992.jpg
 
guiller said:
Congratulations!!
Click to expand...
Thank you.


sfox52 said:
Good job! You've got a thing for meters, huh?
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Thanks, yeah I've got a thing for meters. It's nice when the amp also sounds great and it's not just eye candy.


Vinylcalle said:
Is it really just 650 watts BTL in 8 ohms. That would mean 325 watts in stereo into 4 ohms.
Click to expand...
Yeah,it's "just" 650 in BTL mode and about 330 into 8 ohms and 340 into 4 ohms.

Adda said:
Beautiful Nikko!
Good job fixing it, another Nikko goes on!
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It's my new favorite amp. :banana:
 
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