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The Mighty CR-800

Discussion in 'Yamaha' started by birchoak, Jun 10, 2018.

  1. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
    Just finished relamping a dingy (not anymore!) CR-800 receiver I got at that auction site. Had a pair of new filter caps laying about that happened to match so I threw those in, too. Cleaned up the insides as best I could, new thermal grease on the output transistors. Man, is this thing built well! The way the front and rear panels tilt back and out of the way is simply . . . breathtaking. Someone really thought about what it would be like to go back inside the unit to maintain it!

    It seems to run hot by design, and I saw scorch marks on the power supply board, some on the power transistor board, but I finally hooked it up to some good speakers and, my God, this thing sounds absolutely amazing! Nothing like the CR-600 or other Yamaha gear I've had. The bass extension is simply marvelous, somehow matching my prime bass monster, an 80 watt per channel Scott 380R receiver, and the tuning section still works, pulling in very clear FM from what I can tell so far.

    Don't get me started on the beautiful case and how neatly the chassis slips into it, or those amazing switches and dials. I can't stop playing with them, they just feel so good when you use them!

    Frankly, I am utterly amazed that something with this many parts crammed into it is still working! I haven't seen too many amps/receivers with this many caps/transistors/diodes/etc. per square inch! It's like a Tokyo highrise in there!

    Anyway, color me impressed. They don't make 'em like this anymore. Sigh.
     

     

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  2. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
    It's been tuned to an FM station for over an hour now--no apparent drift and, well, I didn't know FM radio could sound so good! How on earth is this thing still working? I don't think any service was ever done to it (apart from my modest cleaning and filter cap switchout). I cleaned the pots and switches, too, of course. Is this par for the course? Again, how is something this complicated still performing so well? It's a rather unassuming-looking receiver, too--not much to indicate what it's capable of. I'm pretty sure those were Nichicon Gold Tune filter caps that I put into it, which can't hurt I guess.

    Lake Street Dive's "Good Kisser" just came on, and even at this very, very low listening level the dynamics and bass are still there. Amazing. I don't want to turn it off. I realize I'm preaching to the converted in this particular forum, but so far it sounds better to me than other top names I've heard. I got all the caps to repopulate the power supply board but was holding off until I heard what it sounded like--now I'm afraid to touch anything lest the magic smoke disappears! It does run damned hot--that metal grill in the cover is very hot to the touch, especially on the right side over the heat sink--but I'm guessing this is a Yamaha CR-series thing?
     
  3. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,015
    Location:
    Fort Dodge, Iowa
    No.. Not really. How hard are you pushing it ? Load impedence ? Did you adjust the idle current ( bias) ?
     
  4. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,015
    Location:
    Fort Dodge, Iowa
    Warm to the touch maybe.. Not what I'd call hot. Hot is uncomfortable to touch.
     
  5. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
    6 ohms, low volume. Ah, no, I did not adjust the idle current--is that easy? I have a DMM and somewhat know how to use it. I even have those grabber probes on it.
     
  6. Mrv8q

    Mrv8q Well-Known Member

    Messages:
    726
    Location:
    Los Angeles
    Damn! And I thought I loved my little CR-400!
     

     

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  7. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
    Well, this is our first kiss (me and CR-800), so there's the puppy love factor.
     
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  8. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,015
    Location:
    Fort Dodge, Iowa
    Page 17 of the service manual..
    http://sportsbil.com/yamaha/cr-800-sm.pdf
     
  9. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
  10. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,015
    Location:
    Fort Dodge, Iowa
    Imagine that...:biggrin:
     
  11. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
    Adjusted the idle current this morning, and that other thing you're supposed to do which I cannot remember--mid-point voltage. Several times and yes, they were astray. Wow, so very easy to do on this receiver! We'll see if she runs cooler now. I re-capped most of the power supply board with some nice Nichicons while I was in there; will have to order some teeny tiny caps. Checked idle and mid-point voltage again after recapping session--values had not strayed that much. What a beautifully engineered, well-made receiver the CR-800 is, and I had no idea it sounded so good. I had a Pioneer SX-980 that was beautiful, well-made, but sounded very thin and lacking to my ears. I even had it checked out by Audio Lab in Boston and they said ($200 later), "Nope, everything's working fine."
     

     

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  12. avionic

    avionic " Black Knights " Subscriber

    Messages:
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    DC offset
     
  13. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
    That's what they call it in the manual but I'd never heard that term before--DC offset, yes! Thank you for clearing that up and for your help--so, too much power to output transistors = too much heat = premature output transistor failure?
     
  14. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,015
    Location:
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    idle current --> bias ---> quiescent current
    Midpoint -->DC offset ---> DC balance --> I'm sure there are other synonyms.
     
    Last edited: Jun 11, 2018
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  15. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
    avionic, this is the kind of help I need with lingo. Thank you. I had no idea adjusting idle & DC offset was so easy on this rather complex machine. It's so easy I'm going to do it every time I listen to the receiver, just to be on the safe side (just kidding; whoa, what does he sweeten his coffee with?).
     
  16. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
    Can't stop looking at it; feel like I have the hi-fi equivalent of a Faberge Egg. Is it just me or does the tuner sound really, really good?
     
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  17. 39cross

    39cross AK Subscriber Subscriber

    Messages:
    928
    Location:
    Beverly, MA
    I have a CR-1000, the tuner is very good for a receiver, pretty much the equivalent of the CT-800.
     
  18. Dadbeh

    Dadbeh Active Member

    Messages:
    393
    Various bodily fluids flowing lol
     
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  19. birchoak

    birchoak Hi-Fi Nut Subscriber

    Messages:
    683
    Location:
    Amesbury, MA
    Ha ha, yes, I got carried away. If my wife read this and didn't know what I was referring to I'd be in deep $h!t. The amp section is even easy to adjust--no dummy loads needed, no signal generator, just a multimeter! Yamaha has clearly labelled test points so there's not a lot of room for error.
     
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  20. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,015
    Location:
    Fort Dodge, Iowa
    Sounds like the good stuff..:biggrin:
     

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