Yamaha B-2 restoration journey

Discussion in 'Yamaha' started by Mr. Yamaha, Nov 16, 2016.

  1. Mr. Yamaha

    Mr. Yamaha With Kenwood Subscriber

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    Mine all measured 18 or 19 mF and had low ESR, but I replaced them anyway. I would go for the 22 mF KG's and not the CDE's like I did. I will swap them in the end for KG's. And what rottalpha said indeed, move the large 3 Watt resistors to the underside of the pcb.
     
  2. rottalpha

    rottalpha Yamaholic Subscriber

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    yours would be the first unit I hear of, where the main cans are that close to original spec....yet I am willing to bet that if tested in more than two dimensions, it would reveal that they were not that close to spec.

    you should send me those no good used 100v, 105 degrees awful CDEs :biggrin:
    I will trade ya a B-2 power switch for them :deal:
     
  3. Oilmaster

    Oilmaster Ozzy Subscriber

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    I should receive his caps one of these days for full testing on my LCZR bench; I am curious if they measure that as well :)
     
  4. MiamiBoy

    MiamiBoy Active Member

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    The two schools of thought on replacing the large power caps seems to be either A) don't replace them unless they are severely out of spec or B) always replace them. With my other vintage SS amps I lean more to group A's thinking but with these precious B2's (or my other VFET amps) I am more with group B's thinking. They are 40 year old electrolytic caps! How far out of spec do power caps have to go before they pose a threat to the VFETs? Hasn't there been enough advancement over the past 40 years in capacitor technology and manufacturing to justify a proactive replacement...especially if it is your own B2? Some of those in group A are repairing and refurbishing audio equipment for others so that thinking makes sense...as a general repair approach when you are trying to be conservative with repair costs.

    One other capacitor option not mentioned that I installed in my first B2 is the Mundorf MLytic AG MLGO 22000uF 63VDC. They do get a price premium because they are Mundorf's. They are rated up to 125C. Because they are smaller than the originals and their wire leads are too close together I mounted them securely with cap clamps on the back shield cover and then hard wired them to the PCB board. The four Mundorfs each measured UNDER 10% variance even though they are rated at 20%. I have been very happy with the Mundorf caps and am debating weather to install another set in my second B2 or try the KG's.
    http://www.soniccraft.com/product_info.php/mundorf-mlytic-ag-mlgo-22000uf-63vdc-p-4095

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    Last edited: Aug 20, 2017
  5. rottalpha

    rottalpha Yamaholic Subscriber

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    In the B-2, replace them without worrying too much of what the school train of thoughts are. This is an opinion based on testing the main caps in more than a few B-2s. All out of spec, few with spilled can juice.
    I like Mundorf too...not particularly for the PSU, but I would use them if I had them. I am not sure of what effect the long leads would have tho...
     
  6. MiamiBoy

    MiamiBoy Active Member

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    I used about 4 inches of 14awg wire on each leg and quality Cardas solder on each end. The capacitor clamps bolted to the back shield plate provide addition stability and heat dissipation.

    I don't like the way the original power caps are mounted with the "mountain of solder" being the main means of securing them. The B2 power caps should have had some type of cap clamps like most of the other vintage Yamaha amp's power caps. Even my lowly M-40 has cap clamps providing additional stability to their power caps.
     
    Last edited: Aug 20, 2017
  7. rottalpha

    rottalpha Yamaholic Subscriber

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    I am sure that mechanicly you mounted them adequately....I am refering to the caps lead-lenth inductance.....possibility acting as antennas...small decoupling caps would help. Read Oilmaster's posts on this subject. I am not sure to what extent the longer leads would have a negative impact on the noise floor of that PSU...there might be no meaningful impact, but you won't know for sure untill you put a scope in the mix and do a comparison long leads / no leeds. One thing for sure is that the longer leads will not add any benefit :)
     
  8. rottalpha

    rottalpha Yamaholic Subscriber

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    BTW, l like the new magic eye avatar...that explains why I have not see you around in this forum :p
     
  9. MiamiBoy

    MiamiBoy Active Member

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    Yes, I have gone over to the dark side...or the bright side depending on how you look at it.:idea:
    And I blame it all on the VFETs.
     
  10. rottalpha

    rottalpha Yamaholic Subscriber

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  11. MiamiBoy

    MiamiBoy Active Member

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    After reading your and Oilmaster's post I went back in and removed the Mundorfs and disconnected all the wire mess. When I adjusted the leads on the Mundorfs they fit fine! These Mundorfs have adhesive tape on the top so you can stick them to the PCB and their capacitor clamps can be turned to act as supports. No sure why I screwed around with all that wire. Maybe the eclipse today helped realign some of my synapses so I was thinking more clearly. I haven't fully installed all of them yet but when I do I will post a pic.

    I also ordered four Nichicon KG's for my other B2 so when all are installed I should be able to do an A/B test between the Mundorfs and the KG's installed in two different B2's. My main challenge will be trying to convince my wife to put on a blind fold.;)
     
  12. rottalpha

    rottalpha Yamaholic Subscriber

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    :rflmao:
    once blind folded, you make sure your capacitors can deliver :rflmao:
     
    Last edited: Aug 21, 2017
  13. MiamiBoy

    MiamiBoy Active Member

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    I am not hijacking this thread as long as it is B2 refurb related...right?
    Below is a pic of the Mundorfs installed directly to the PCB without wire extensions. Notice that the caps are supported and resting on the cap clamps. They are not just suspended in air.

    Also, thank you Mr Yamaha for posting excellent pics of your refurb journey. I know that taking all those photos and laying out the parts in an organized manner is a lot of additional effort on top of the refurb you were dealing with. Much appreciated.

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  14. rottalpha

    rottalpha Yamaholic Subscriber

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  15. Mr. Yamaha

    Mr. Yamaha With Kenwood Subscriber

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    Only a bit :p If you are going to document your own resto, maybe it's easier to start your own thread :naughty:

    Looks better than before!

    Thanks! :D
     
  16. MiamiBoy

    MiamiBoy Active Member

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    No I am not going to start my own resto thread or post any more pics....except for this one. It is B2 related because I was reinstalling the Mundorf caps during the middle of the eclipse. This is a photo showing the Neil deGrasse Tyson spaghetti strainer eclipse viewing technique. Too cool not to post, right?

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    Last edited: Aug 24, 2017
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  17. Nashou66

    Nashou66 AK Subscriber Subscriber

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    Multi eclipse!!!!!
     
  18. MiamiBoy

    MiamiBoy Active Member

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    Mr. Yamaha, this thread is a valuable contribution to this forum and will be referred to by many attempting all or some of the documented B2 refurbishments for years. Given that, I wanted to make two suggestion before too much time passes and you are off on another project.

    First, did you document the individual replacement parts in some form that you could upload. Most parts are noted somewhere in the thread but having a single summary would be very helpful.

    Second, there are a number of photos that you uploaded that are no longer displaying. Just a Photobucket link error message is showing as though the photos were deleted from Photobucket. If you feel these photos are still relevant could you re-upload them to the post. If not just delete or edit them out of the post.
     
  19. Mr. Yamaha

    Mr. Yamaha With Kenwood Subscriber

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    That would be awesome, wouldn't it? :rolleyes:

    All pictures were initially uploaded through Photobucket. Until they changed their policy: pay 500 dollars a year or no more 3rd party 'hosting'.

    I already spent 7 hours on re-uploading all pictures directly to AK a few weeks back so that the thread stays intact for fellow AK'ers who may be interested. But also I do have limited time for my hobby.

    I did document all parts I used, which took me, @Oilmaster and other AK'ers (derrived from their threads) lots and lots of hours. I read a lot on AK and on the net to figure everything out. That's what made it a restoration journey. Almost everything you need to know can be found on AK and the internet. I wrote 13 pages about this journey and mentioned which parts I used and uploaded lots of photo's tot illustrate, so I hope that will help you with your own journey :bigok:
     
    Bert 1100 likes this.
  20. MiamiBoy

    MiamiBoy Active Member

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    Well...I just thought that since you already scaled Mt. Everest you wouldn't mind going back up to build a ski lift for those of us who want to enjoy the down hill ride without the climbing.
    :whip::p
     
    Last edited: Aug 28, 2017

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