Help me resurrect my CR-1000!

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

  1. avionic

    avionic " Black Knights " Subscriber

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    [​IMG] Little " outhouse" TO-92 case style are the noisy ones.
     

     

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  2. sssboa

    sssboa Well-Known Member

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    They all have this shape in old Yamahas. But some were saying here that only those with LGB print are to be replaced. But there's plenty of old threads about it.
     
  3. Sir Pants

    Sir Pants New Member

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    Hey sssboa!
    Thanks for your input. New tantalums, eh? I’ll have to think about that. Sounds deluxe!

    From the state of the power supply, and how long it sat idle, I really expected it to sound tired and in need of more work. Actually, now that I have it all clean and working and hooked up to the NS-670s in the bedroom, I am pretty impressed by just how fresh and quiet-sounding it is and I may just leave well enough alone for now on the tuner recap and just listen to it for a bit.

    I have read a lot of posts pro and con on the notorious c458s—but my (more limited I am sure) experience has usually made me lean towards replacement, LG version or no. It made a huge difference to a noisy Sansui 2000a I just did, and also my Kenwood KA-7002 that must have had like 30 of ‘em. In a couple of other amps, too, it has seemed to lower the noise floor, though of course they are not the only troublemakers out there as far as noisy vintage transistors. Seems to be most critical in tone and EQ stages; I haven’t dealt with them on tuner boards before. That said, they seem to be doing their job in this case, this CR-1000 doesn't have the noise issues of those others so far!

    I’ve only seen one c458 outright fail; that one was biasing the outputs on a CR-820. The CR-1000 had those too, I already replaced those when I did the main amps.

    I’ll be revisiting this, I guess, whenever I decide to get back in there on finish recapping...but right now there’s an HK 930 calling me with some similar power supply-to-tuner issues...this hobby (addiction) is neverending, isn’t it?
     
  4. sssboa

    sssboa Well-Known Member

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    So you replaced those c458s pressed against radiators on main amps? It had never been done. I asked some time ago here and every one said they kept them. What did you use and have you tested bias/idle currents if all is ok? Has it worked for some time now?

    There are 5 c458s on power board too. I replaced those.

    You may leave tuner all as original. I never had problems. At least assign low priority to this.

    About tantalum, they were considered superior to aluminium back in the day so why would I downgrade?

    I was thinking about HK930 too. How does it compare to CR-1000? Doesn't bother you lack of any speaker protection circuit /relay? I see you like early 1970s gear like me. My favourite sound so far is CR-1000, would you recommend something of other brands sounding close to it? I found Sony STR-6065 so far being very close in sound.
     
    Last edited: May 2, 2018
  5. sssboa

    sssboa Well-Known Member

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    541
    Damn. Post went 2 times
     
  6. fernarias

    fernarias Well-Known Member

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    I'm doing the same for tants, replace with new or film where appropriate.

    As for the 2sc458s, they have lasted 40 years and longer, just how bad can they be. I do replace with 2240s (while supplies last) but I'm replacing everything that can be replaced these days.
     

     

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  7. sssboa

    sssboa Well-Known Member

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    If someone wants to use new tantalum caps I have a warning about non-branded or so called Multicomp caps which is a synonym for not branded parts from Taiwan. They are cheap like dirt. I used 2 of them on tone of CR-800 and they caused crackle in volume pot straight away.

    I read that tantalum don't age on shelf (or even if they drift on shelf it reverses under voltage) so NOS maybe would do though I never tried. New branded tants are more expensive than film sadly.
     
  8. Sir Pants

    Sir Pants New Member

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    Yep, I replaced them on the CR-820 with ksc1845s just as I'd do elsewhere, couldn't set bias without a working transistor there. This was before I understood about the particular requirements of bias transistors (though I can't honestly say I fully "understand" now if anyone wants to school me!) Formed some thermal compound around them to form a heat bridge as they had to go in "backwards." It seemed to work fine after that, though. When I got to the CR-1000 I just threw caution to the winds... If I was doing it now though I'd probably just leave them... After a nice long warm-up, all the amplifier adjustments were a breeze, went through them several times, although maybe it would not be a bad idea to monitor things for a while. Time will tell. Maybe I just got lucky. Maybe not. Is that a bit of distortion I hear! You guys are making me paranoid. :confused: Kinda forgot I had done them in this unit until we had this conversation! If the ksc1845s don't work out I suppose I could start matching from my bucket of used c458s...maybe' I'll just do that anyhow. As you say, fernarias, they lasted 40 years; they don't really fail, just get a bit hissy as far as I can tell.

    Got the ones in the power supply too.

    I like the quiet of the Fairchilds but who can say how they will sound in 2058?

    Other than some testing through headphones, I haven't had the privilege of hearing the 930 yet, though I have a refurbished 630 that I adore. It drives speakers much better than any 30wpc should...I expect great things from the 930 at what, 48wpc? Doesn't seem like a ton, but those twin transformers are doing something special. The speaker relay thing is concerning, but so far hasn't been an issue. I definitely won't be hooking up my good speakers until it's all gone through and adjusted. How many speakers did these things kill I wonder? I will tell you I am very very careful how I hook up speakers to my 630 and switch speakers OFF before turning the power off and on.

    I was reading something recently about the superior abilities of the HK in reproducing square waves, and recalled listening to a familiar recording that had lots of distorted, electronic sounds after I first had the 630 in my system--a lot of amps smooth out those rough edges a bit, but the HK reproduced even that degree of harshness faithfully enough that I was convinced I had a real problem for a moment...real distortion instead of a recording of such. I run it with a Sansui 2000A as it seems to have a better preamp; looks a little weird with 2 receivers on my shelf but it really is a lovely combination to hear.

    Fortunately it is good at reproducing more musical sounds, too.

    Still forming an opinion on the CR-1000, but it does sound very good and does just about everything right. Sonically, the HK is a different animal although both are good flavors. I don't think one would liken most Yamahas to the Pioneer sound but this one reminds me a bit of my QX-949A though not as warm and cuddly. But I'd say yeah, sssboa, Sonys probably come closest to this particular sound profile out of the gear I've had the pleasure to hear; especially the STR-6800SD (another fine receiver.) or V5! That's my hot take anyhow.

    Oh, those solid aluminum caps...my nemeses. Looking at a handful of sky-blue Sanyos currently mucking up the tone section of an SX-828. Dammit I have too many projects. Yes I gravitate towards early/mid 70s stuff! I have some later 70s gear that sounds great but I love real wood, real glass, real machined metal knobs...blackout dials with lovely blue lights. Works of art.
     
  9. fernarias

    fernarias Well-Known Member

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    957
    Location:
    Merced, CA
    Unfortunately, since they stopped using lead, new transistors won't last as long (definitely not 40 years). Even less if they start forming tin whiskers on the pnp/npn wafers (maybe not plastic encapsulated but to-3 that are in a vacuum) where the wafer connects to the pins. Just something else to worry about.

    Tants made in China. Yeah stay away from anything made there (saves me money in the long run since there's almost nothing to buy that isn't made in China).

    Personally I like the way the cr-1000 sounds. It's definitely built better than the cr-2020 and cr-2040 that sound better. It will be nice when it's finished. Looking forward to the rest of this thread.
     
    zaibatsu and sssboa like this.
  10. zaibatsu

    zaibatsu Well-Known Member

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    569
    Very interesting you'd say that, I tried to find some lifespan-before-whiskers data on ROHS transistors recently and couldn't find anything concrete. Surely lab approximations must exist at least? I'd appreciate link/s if you have any, particularly case-size specific data.

    Do you think the encapsulation stops the whiskers forming internally? It wouldn't be hard to tin external leads with leaded solder, but I assumed encapsulating wouldn't actually stop the problem internally. Hopefully you have something concrete, it was only a month ago I was looking.
     
  11. fernarias

    fernarias Well-Known Member

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    957
    Location:
    Merced, CA
    Most data/research I've read comes from hobbyist and technicians. I thought that encapsulation would stop the wiskers but it looks like it won't (looked into it after my post). I'm guessing the military will start looking into this when one of their f35s goes down because of a short circuit.

    From onsemi:
    Tin Whiskers
    Mitigation Strategies

    Changing the lead plating material to 100% matte Sn (tin) from SnPb raises industry concerns about tin whisker growth. ON Semiconductor has implemented the following mitigation strategies to minimize the occurrence of tin whiskers.

    • Increased the plating thickness from 5 µ m to 7.5 µ m minimum; 10 um nominal.
    • Implemented a post - plate anneal of 150 ° C for 1 hour within 24 hours of plating
    • Implemented strict plating process controls
    Whisker Testing

    ON Semiconductor has conducted tin whisker testing following the guidelines of JEDEC standard JESD22A121. Testing has been conducted on packages utilizing Alloy 42 and Cu leadframe materials with matte tin lead finish. Three test conditions have been used to evaluate whisker growth: Temperature Cycling (-55/+85°C) Ambient Storage at 30°C/60%RH, and High Temperature/High Humidity Storage at 60°C/87%RH.

    ON Semiconductor's internal whisker acceptance spec is 50µ maximum length. All whisker test results to date have passed this spec.
     
    Last edited: May 3, 2018

     

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  12. sssboa

    sssboa Well-Known Member

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    Damn guys. I changed so many vintage transistors for new. I didn't know I would have to shave their whiskers after 5 years. Government must do something about it! Redirect money from global warming research or something.
     
  13. Sir Pants

    Sir Pants New Member

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    That's some interesting info from OnSemi there fernarias, thanks for that. It is good to know they have a mitigation strategy though how does one evaluate its effectiveness vis-à-vis longevity? I am guessing we will just have to wait and see...

    I have to say, I am a fan of improbable word combinations, and "internal whisker acceptance spec" is not a phrase I'd expected to encounter today. Personally speaking, my external whisker acceptance spec has gotten a bit lax as of late... definitely over the 50µ maximum length!

    Silly EU, always looking after peoples' health and wellbeing...:rolleyes: Don't know where you all are, but here in the US I think we just freed up a lot of that global warming research money, we could look into it...after all the Cabinet members' wives all get new diamond shoes of course. :D

    Update on the ol' CR-1000: After an extended listening session it became apparent that ksc1845 was not a good replacement in the bias circuit. Went back in today to revert back to the c458s, and found to my bewilderment that when I had made the change some 12-18 months ago, I had only done one side. Can't really remember with any certainty now why I had done it in the first place. Oh well, back to normal now, running clean and cool. Discovered while setting idling current that one of the trimmers has gotten very touchy and probably needs replacing. I was able to set the current in the specified range but not near as exact as I would like. Thinking of replacing all 6, they are 4.7k ohms, any suggestion for replacements? is 5k alright? Maybe something like these?

    https://www.mouser.com/datasheet/2/54/352-776447.pdf

    The only other thing I am currently unhappy about an unbalanced volume control--I get almost nothing out of the left channel until about 1 on the volume control, it doesn't catch up with the right channel until about 1.5 but tracks with it after that. I do a fair amount of late-night listening at lower volumes (love the variable loudness slider for this!) and the weak left channel bugs me. I might have missed the volume pot when I cleaned the controls, going to clean the heck out of it tomorrow and see if that makes a difference; any other suggestions?
     
  14. sssboa

    sssboa Well-Known Member

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    541
    No cleaning will help your unbalanced low volumes. Volume potentiometer is the weak point of CR-1000. They didn't go for Alps, could have been better. You may mitigate with more loudness at low volumes. I had 3 units and it was all the same, some had left channel coming as second, some the right.
     
  15. Sir Pants

    Sir Pants New Member

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    Ugh, kind of feared that might be the case. Same story with the Harman Kardon 630. Pots and switches are cheap. Wonder about the 930 I'll be getting into soon...
    Man this thing is sounding good right now though!:music:
     
  16. sssboa

    sssboa Well-Known Member

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    541
    Maybe one of these? All 4.7k
    https://www.digikey.co.uk/products/en/potentiometers-variable-resistors/trimmer-potentiometers/80?k=trimmer+4.7&k=&pkeyword=trimmer+4.7&FV=ffe00050,mu4.7+kOhms|2085&quantity=0&ColumnSort=0&page=1&stock=1&pageSize=25

    I had the blue ones, both shapes in Yamahas CA-1010 Integrated, not sure if they were easier to set than the original. Transistors matter most.
     
    Last edited: May 5, 2018

     

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  17. mbz

    mbz AK Subscriber Subscriber

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    Not familiar with the CR1000, done a few CA-1000's. Will only use Bourn 3296P series, I used 5k, often 2 of the legs are tied together, in anycase the 5k is
    within 4.7k tolerances.
     
  18. Sir Pants

    Sir Pants New Member

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    18
    Thanks for the suggestion, i will check out those trimpots!

    Everything at the moment is stable, cool, and sounding good!
     

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