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Help me resurrect my CR-1000!

Discussion in 'Yamaha' started by Sir Pants, Apr 30, 2018.

  1. Sir Pants

    Sir Pants New Member

    Messages:
    18
    I picked up this very dusty CR-1000 about a year and a half ago--I knew it was going to be a project but it has become quite the problem child! Enough to force me out of my lurker status to ask for some help!

    The story so far: The thing looked like it had a useful life, then sat on a garage shelf for 20 years...an even, undisturbed layer of oxidation and grime everywhere. On first listen, it was working...sort of. There was music, but also very LOUD buzzing through the headphones, from the power supply I assumed. Setting to work, I found lots of bad caps on the PS board. Replaced everything with new Nichicon PW and ES and got rid of a handful of 2sc458s since I had replacements on hand. Should have improved things but post-recap I couldn't even get a relay click. One by one, the big power transistors on the board (2sc1061, 2sa671) started to go bad in the most aggravating way: failing under power but every one of them tested good out of circuit. Shelved the receiver for over a year in frustration while I worked on other projects but I got brave and dragged it out again this week. Stuck in some MJE15031/2Gs and at long last we have a relay click and a stable power supply. Recapped the main amp boards while I was at it (only like 3-4 caps per side) and we have a working amplifier section. What I am hearing so far only makes me more excited to get this classic working and in rotation! All adjustments done, the main amp is dead quiet; some noise in the tone sections but I'll worry about that later--we've got bigger problems. The tuner section is DEAD. No lights, no meters, no sound.

    Maybe it has been too long and I am not recalling correctly, but I seem to remember getting FM when I first tested it out? Seems like every time I fix one thing on this unit, another thing breaks...Anyway, I've been poking around the tuner section, checking what voltages I can read from the more legible scans of the service manual I can find, but I could use some helpful advice at this point, a more systematic approach.

    What I've found so far: Checking the voltages on the board against the printed values, 12V and 33V are good; MU/MUB (muting I assume) should be 7.4V but read 1.1 and FB (function board?) wants 11.3V but has .336. Traced back to the FM selector switch, gave that whole bank of switches a good cleaning but no difference. I don't really understand where that voltage originates, and where I ought to probe next. Nothing is forming a coherent picture to me yet. Where to start? Any guidance from the Yamaha gurus is appreciated!

    Regards,
    Pants
     

     

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  2. avionic

    avionic " Black Knights " Subscriber

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    Welcome to AK..
     
  3. avionic

    avionic " Black Knights " Subscriber

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    Power for the tuner is MB off the emitter of TR805. Looks like 33 vdc.As well as FB 11.3vdc
     
  4. avionic

    avionic " Black Knights " Subscriber

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    Have a close look at FR805 and FR807 -- in the 12volt regulated power supply.
     
  5. Sir Pants

    Sir Pants New Member

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    Thanks Avionic! I have been reading and learning here for ages, it’s high time I participated.

    I have 32.9V coming off TR805.
     
  6. avionic

    avionic " Black Knights " Subscriber

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    Should also see around 32.9V on the collectors of TR131 and 132 in the tuner section.
     

     

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  7. Sir Pants

    Sir Pants New Member

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    Resistors look good, replaced them when I rebuilt the PS I think; I have +12V and -12V at TR807 and TR808 and at the pins. Hmmm.
     
  8. Sir Pants

    Sir Pants New Member

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    18
    ~33.4 at TR131, 132.
     
  9. Sir Pants

    Sir Pants New Member

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    Missing that 11.3V at FB pin on the tuner sheet—where does that 11.3V come from though?
     
  10. avionic

    avionic " Black Knights " Subscriber

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    12 v regulated power supply
     
  11. avionic

    avionic " Black Knights " Subscriber

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    Make sure your wires from the +12vdc and - 12vdc supply to the tuner board has +/-12v on both ends.
     
    Last edited: Apr 30, 2018

     

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  12. avionic

    avionic " Black Knights " Subscriber

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    Red tuner LED's out as well ?
     
  13. Sir Pants

    Sir Pants New Member

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    Yep, LEDs as well.

    I think I have found something significant, probably.
    Checking the 12V wires at your suggestion, I find: the 12V+ (orange) and 12V- (violet) from the power supply have 12V at the tuner as well. However, the orange wire that should supply FB on the tuner board goes first to the IC connector at the Function switch, where I imagine it should energize the yellow wire that goes to FB on the tuner sheet when the FM switch is engaged. I have ~12V where the orange wire enters the connector, and I have continuity from the yellow wire at the switch to FB, but no voltage at FB when I engage the switch. I can insert my probe into the slot on the connector for the yellow wire and get ~12V when I engage the switch! But the yellow wire itself although seemingly intact is not getting voltage. So, possibly a break inside that connector somehow? Kind of a weird and finicky problem but nothing else makes sense at the moment. Thoughts?
    Have to take a break for some yard work just now, but I will investigate further and report back when I get the chance. Thanks so much for your help and suggestions; we are closing in on it I hope
     
  14. avionic

    avionic " Black Knights " Subscriber

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    Could very well be a bad solder connection on the circuit board part of the connector.. If its the connector itself then ...
    1.try to find a replacement connector
    2.Remove borked connector and run the wires directly to the board.
     
  15. Sir Pants

    Sir Pants New Member

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    Wish it was a solder joint—sounds like the easy solution, but it still looks to be a break inside the plastic connector between the pin and the wire. Tried deoxiting the pins and socket of the connector but nothing. May just solder the yellow wire to the board and call it good! Jumpered the 12V supply to the FB pin to confirm tuner operation and i am picking up NPR right now so all is fine there. Still no LEDs though and all the signs of a filthy tuning capacitor but those are problems for another day.
    Thanks again, Avionic, for helping me think it through I consider this one a success.

    Cheers,
    Pants
     
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  16. avionic

    avionic " Black Knights " Subscriber

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  17. Sir Pants

    Sir Pants New Member

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    Hey— another CR-1000 restoration question if you’ve still got your ears on...

    Looking at this tuner section I must say I have never seen such a collection of those little blue tantalum capacitors, which considering the age-related failures I’ve seen on this receiver already, makes me a little nervous. Any merit in your opinion of replacing those with some combo of stacked films/nichicon ukls or would you leave well enough alone? How about all those c458s? Any improvement to be had or would I just be buying mysel an expensive alignment?

    Getting ahead of myself really but just curious.
     
  18. avionic

    avionic " Black Knights " Subscriber

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  19. Sir Pants

    Sir Pants New Member

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    Okey dokey.
     
  20. sssboa

    sssboa Well-Known Member

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    Most of tantalums there are small 1uF/2.2uF/3.3uF one is 0.68uF two are 10uF. Replace them with aluminum lytics, I wouldn't do, as Master Yoda would say. Actually the most expensive option is to replace them with new tantalum which I was crazy enough to do on my 2 units (I used Kemet tantalum caps), just for 0.68uF I used film.

    Out of 5 units of CR-1000/CR-800 I ever had only one original tantalum cap went bad causing crackling in one channel, it was 1uF on tone. I measured them all while replacing and only 0.68uF/1uF/2.2uF measured badly, 3.3uF and higher seemed ok.

    On tone, filter and phono in one CR-1000 I replaced all tantalum caps with Kemet tantalum caps while in my other CR-1000 I replaced all 4.7uF and smaller with WIMA and EPOCS polyester, bigger than 4.7uF with Kemet tantalum. Difference in sound is enormou..., no actually there's no difference in sound, sorry all audiophiles.

    There are like 12 of 2SC458 on tuner, then a few 2SC460 which are kind of the same, they may be both replaced with KSC1815 but it would be like 20 transitors to replace, I never did that.

    Personally I don't understand that talk about how bad c458 are, I never saw any go bad and having them 12 on one board at least one should go. Actually on my CR-800 (same FM tuner as of CR-1000) I had 2SC460 gone bad. On schematics some c458s are marked as LG which some say are the worst kind of c458, they should have LG printed on them too.
     
    Last edited: May 1, 2018

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