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

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Old 10-07-2012, 04:23 PM
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Pacific Stereo Pacific Stereo is offline
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Concept 12.0D restore (and nudies!)

A little bit ago, a 12.0D showed up at the lab. A customer had bought one via eBay and had the seller send it directly to me for evaluation and rehab. It was in very good shape except for a couple of problems. One was that the function switch was busted off. Doh! Another was some scraping along the top right edge of the bezel. Other than that, it was just beautiful.

Let's start with the inside.



Not bad. I haven't seen the inside of a 12.0D in a very long time. There are two samples sitting on a shelf in the lab that belong to me, but the operative term here is "sitting." I think that the last time I actually worked on one was in the early 80's. A lot of folks think that the 12.0D and the 11.0 are nearly identical on the inside, but this is just not so. One look reveals that they are completely different animals. For one, the 12.0D is not built in the amazingly tech-friendly modular way that the 11.0 is, and servicing it is much more difficult than servicing an 11.0. The boards don't just come out, they have to be finessed and wrangled with, over and over and over. This is a real bummer. Also, the circuit topologies are definitely different, and this explains why they sound different from each other.

Here's a look at the power supply board. Pay close attention to the seriesed diodes near the right of the board, next to the fuses. Someone has removed the bridge diode and incorrectly substituted diodes (can you say "this is half-wave plus one diode-drop, not full-wave rectification?") in its place. While one can easily replace a bridge diode with four individual diodes, this was not done here. I have to say that I have not seen anything like this before. I hope it was not one of our guys.



Full o' dried-out and leaking caps. And the dreaded carbon-glue, everywhere. So that's the first order of the day; redo the supply. Also, this is the most difficult board to do (although it does not look like it ought to be), so I tackle it first. I have the original bridge diodes, so the diode abortion goes bye-bye.

It looks much better.



After that, I tackled the tuner, the preamp and control boards, the FM tuner and control boards, switches and controls, surge prevention relay and that sort of thing. And of course, more carbon glue. Following that adventure, I started on the output boards.



If you look at my 11.0 thread, you'll see that these are quite different from those boards. No offset adjust, for one thing. The input differentials have GOT to be matched for Hfe. After some TLC, the boards look like this.



Here's a look at the bottom of the unit.



Very different from the 11.0. Here's a look at the inside afterward:



Here's most of the parts (this is what I could scoop up from the bench; I know some are missing) that got changed:



One of the things that's rather a bummer is that one must change all of the parts that were made with silver. See all those TO-126 transistors? They all have silver-plated leads. None of these parts are bad. However, they WILL be. As the tarnish progresses up the leads and under the device case, they will become leaky and will degrade and fail. While I hate to change out perfectly good parts, I know that "perfectly good" is temporary.

One cannot change a bunch of parts in the FM section and not have to do an alignment. The bad news is that as with all Concept products, there was never a published alignment procedure. We literally depended upon our tech's ability to know tuners, use the test gear and the existence of institutional knowledge. After all, you could probably get the guy who designed the FM section on the phone! I guess we never anticipated that we might go out of business. Happily, those brain cells haven't been killed and I was able to perform a complete and correct FM alignment. And here's what she looks like, all done:







And a look at the back:



See something missing? That's right. No AM antenna. The 12.0D does not do AM.

After a burn-in, she is making delicious music. Can't wait to send her off to her new owner!
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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; 11-26-2012 at 11:51 AM. Reason: Forgot a photo!
  #2  
Old 10-07-2012, 04:32 PM
oskimo oskimo is offline
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Very nice....

Beautiful outcome!
  #3  
Old 10-07-2012, 05:11 PM
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macman007 macman007 is online now
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Indeed sir the work of a true craftsman and artisan. Pacific, your work and superior attention to detail never ceases to amaze me. Guys like You, Skywave, Tinman, Russ Bachman, NakDoc and a multitude of other technicians on this site are the life blood and the shining examples of a dying breed of guys who do quality work and always look out for the best interests of customers and fellow enthusiasts.

Lets hope they are not the last of their kind. As in my field, auto repair and restoration, Master Tech's are a dying breed much to my chagrin.

The can do guys are getting hard to find in every employment field today.
  #4  
Old 10-07-2012, 07:59 PM
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The 12.0D along with the 11.0 are favorites of mine. IMO, in stock form they compare favorably to any Silver Era receiver you care to name. In PS restored form, I would bet they take the TROPHY.

Thanks for clearing up the circuit differences between the two. Superficially, it sure looks like Concept swapped the cut core for a toroid and then upped the voltage rail a little. Why Concept departed so much from Schramm's original is a mystery to me.

I always liked the FM tuner. It was the first truly fast digital receiver that I can name and works as well as any modern tuner. I haven't played with a Toshiba 7150 or a JVR Chronotuner so the 12.0D may not be the first effective digital tuner. However, the 12.0D tuner is far superior to the balky R-2000 tuner, which has a preset battery that always leaks. The 12.0D's little transformer that keeps the station presets and time is a nice touch.

IIRC, the 11.0 was Japanese and the 12.0D was Korean. Any differences in build quality that you can see?
  #5  
Old 10-09-2012, 09:37 AM
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Pacific Stereo Pacific Stereo is offline
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Yes, this was the first early digital tuner that got most everything right. It works very well, except when the power fails!

As you say, the 11.0 was made in Japan, and the 12.0D was made in Korea. The components, boards, and chassis all remain of the same quality. However, no doubt due to cost considerations, the modular design (so brilliant) was abandoned and things like wire dressing and routing are a bit sloppier. This doesn't hurt anything and I understand why bean-counters would make those choices, but it sure makes comprehensive servicing a lot more trouble!
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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
  #6  
Old 10-09-2012, 10:25 AM
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VintageSteve VintageSteve is offline
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As always, a beeeuuutiful restore! Love seeing the detailed pics of your work.
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  #7  
Old 10-09-2012, 01:48 PM
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StereoGaryo StereoGaryo is offline
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Gorgeous restore PS.
  #8  
Old 10-09-2012, 02:01 PM
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Nightingales Nightingales is offline
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Awesome job, PS! Can you disclose how many hours you put into the restore?
  #9  
Old 10-09-2012, 03:51 PM
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Pacific Stereo Pacific Stereo is offline
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Thanks. I really can't disclose the number of hours, but I can tell you that it was a LOT, and significantly more than the customer was invoiced for.

Quote:
Originally Posted by Nightingales View Post
Awesome job, PS! Can you disclose how many hours you put into the restore?
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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
  #10  
Old 10-09-2012, 07:11 PM
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DaveInVA DaveInVA is online now
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Very nice! Haven't seen one of those in many years.


Dave
  #11  
Old 10-09-2012, 09:03 PM
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Quote:
Originally Posted by Pacific Stereo View Post
Thanks. I really can't disclose the number of hours, but I can tell you that it was a LOT, and significantly more than the customer was invoiced for.
That happens a lot, doesn't it?

Sometimes if people really knew how much time we put into these things.....

Marc
  #12  
Old 10-10-2012, 07:54 AM
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Nightingales Nightingales is offline
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Quote:
Originally Posted by Pacific Stereo View Post
Thanks. I really can't disclose the number of hours, but I can tell you that it was a LOT, and significantly more than the customer was invoiced for.
Totally understand and not really surprising... just following the pictures tells me this was a bear of a job!

Marc
  #13  
Old 11-07-2014, 07:25 AM
paymenow paymenow is offline
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PS, the photos of the right channel amp board show c606B originally installed opposite of the board polarity marking. All that I have looked at are this way. In your after photo it appears that you installed the replacement to agree with the board marking. Am I interpreting this photo incorrectly?
  #14  
Old 11-07-2014, 07:51 AM
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Pacific Stereo Pacific Stereo is offline
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Good catch. Yes, that part goes in opposite from the board markings. The photo in the thread was taken before I realized I had installed that part backwards.
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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
  #15  
Old 11-07-2014, 12:21 PM
paymenow paymenow is offline
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Actually, I only caught it because I ran into it on the 12.0 that I am refurb'ing. Looking at the schematic, the positive side of C606 goes to ground through jumper J12. But,
the 12.0s that I have and looked at are opposite i.e. with the negative side to ground. I looked at your photos for reference but decided that the board was marked wrong otherwise all of these 12.0s wouldn't have been working all these years..
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