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Pacific's Restorations You can see all of Pacific's vintage gear restorations here.

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Old 08-03-2012, 11:32 AM
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Pacific Stereo Pacific Stereo is offline
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Join Date: Feb 2010
Location: Somewhere in paradise!
Posts: 12,006
Kenwood 600 Supreme restoration (and nudies!)

I've had a 600 in the lab for the last week or so. The owner wanted a full restoration, so it's been thoroughly gone through. EDIT: more units below, keep reading!

These are absolutely beautiful integrateds, both cosmetically and electronically. Full dual-mono everything, class-A prestages, a nice (if oddly complicated) power supply, FET differentials and direct-coupled power stage with no caps in the signal or feedback paths. Very sweet and smooth-sounding, with excellent detail and speed.

There are a lot of things to do to these, and they are damn annoying to work on. Since the power supply is the one thing that is easy to work on, I started with that. Why the rest of the amp isn't made this way, I simply don't understand. But it isn't.



This supply got a full recap, replacement of regulators, error drivers and zeners, "carbon glue" cleanup and tweaking of gains to bring voltages to where they belong.



I always seem to forget to take "before" photos, and I did again this time, too. Suffice to say that the amp was dirty inside, with a lot of "sticky dust" that doesn't just blow out. The main filter caps on these always tend to be bad, but this one's were still all right. However, since the unit was apart and this was the opportunity, the customer and I agreed that it made sense to go ahead and change out the filters, since it's difficult.

And look at that BEAUTIFUL precision attenuator! Oh, the stuff of dreams.



I ended up using some snap-in parts because I don't really like what's available in the screw-terminal department. These are better parts with a ripple-current rating of 11 amps each. They're slightly smaller in diameter than the parts they replace, so I glue some foam to the new parts to make them fit in the clamps correctly. You can just see it between the clamps and the parts. Oh, and see the output relay on the board in the center left? Guess what you have to do to change it? Yup. Remove those capacitors. Oh. You want to remove the capacitors? Remove the transformers.



All the other boards were recapped and serviced as well. The power stage boards were serviced, drivers replaced (those funky-can 2SA810s and their counterparts are time bombs), new sealed Bourns bias and offset pots were installed, and a few other various and sundry items were addressed.

Then it was time for BeautyMaker. This customer wanted the outer case redone, so along with the usual, she got some new paint, too. I've developed a method that duplicates the factory "splatter paint" effect quite nicely, and that was done here. So a little paint and polish, and voila!







After a 12-hour burn-in, she is ready to go back. Hate to do it, though, I'd just like to keep her!



NOTE: The volume knob is quite gouged up on the front. It's not easy to see because of the lighting, but it's there. I'd like to find a replacement for this customer. So if y'all wouldn't mind keeping your eyes peeled, I'd appreciate it.

Photos are copyright 2012 by Pacific Stereo. Absolutely NO unauthorized use or copying is permitted, and specifically, NO EBAY USE is permitted.
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pacificstereo.net "Make your own kind of music!"



I RESTORE VINTAGE AUDIO AND VIDEO GEAR. Master technician for Concept, Quadraflex, Calibre, Pioneer and Sony. Endorsed by Richard Schram for Concept product restoration. Factory technician for both Yamaha and JVC. Sonics consultant for Denon. Pacific Stereo store manager, service manager, Central Service lead tech, liquidator at our demise. Pacific Stereo curator. Infinity IRS dealer. Music buyer for one of the first CD retailers in the USA. Authorized servicer for virtually every brand on the planet at one time or another. Music addict. Mastering & recording engineer, weaned on a Neve (no other console sounds like a Neve!). Industry-respected ears. Head Tapehead.

Need vintage audio & video repair and restoration, or unobtanium semiconductors and parts? Ask me! And do visit the website: pacificstereo.net

Last edited by Pacific Stereo; 09-21-2016 at 09:37 AM. Reason: added info
 


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