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B-1 Quickie

Discussion in 'Yamaha' started by rottalpha, Dec 11, 2017.

  1. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
    Middle of Crook County
    Hi Gang, time to start a B-1 thread of my own and stop highjacking other's.

    A little while back I purchased a nice looking B-1 with UC-1.
    I played it for a bit after I got it and it sounded so so, but nothing to write home about. At low volumes it was definitely lacking the definition I expected. It was also getting extremely hot...way hotter than my BX-1s which I was also running at the time.
    Needless to say, It needed TLC, so I packed it up and stored it ....until recently.

    Time has come to dust this B-1 off and give it a "Quickie". The goal is to have it singing like a canary by Christmas. I do not intend to do a full rebuild just yet, but I will go a bit beyond to the average recap job.

    Besides a lot of dust and a bit of corrosion on the top of one of the driver boards brackets, I do not see anything out of ordinary. The corrosion seems to have originated from a liquid spill at some point in the past. Very minimal damage and non consequential now...
    Here are some shots of under the hood:
    IMG_20171126_205626182.jpg

    Some heat damage to one of the caps in the middle PSU/Protection board
    The good news, this thing is cleaning up very nicely. I think I will make a model citizen out of it :D

    Here are some of the individual boards:


    IMG_20171127_204818972.jpg
    IMG_20171130_033001679.jpg
    This thing was well roasted. One of the legs was no longer attached OUCH! Lucky Lucky B-1!
    This is a bad design. The three fat 2w resistors below are roasting this cap every-time the amp is on. I am moving it to the back side and will stagger those resistors so that the lower ones do not bake the ones towards the top.
    Still working on it, but this is kind 'a what I have in mind:
    IMG_20171211_140819792.jpg
    IMG_20171211_140802171.jpg


    Nothing eventful on this board, except dirt and corrosion on the TO220's heatsinks:
    IMG_20171128_231526535.jpg
    Edit: I should have mentioned that I replaced a hand full of 458s on this board
    IMG_20171211_140733064.jpg

    IMG_20171128_231515333.jpg
    IMG_20171202_141526428.jpg
     
    Last edited: Jun 11, 2018

     

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  2. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
    Middle of Crook County
    continued...
    IMG_20171128_232431904.jpg IMG_20171211_140752791.jpg
    here I committed the ultimate sin by a certain someone's standard in terms of replacement components choice....I promise to repent :p

    also...ran out of silver heatsinks so I went to black instead.

    IMG_20171211_140336803.jpg IMG_20171211_140406000.jpg

    IMG_20171211_140525921.jpg

    on the driver boards I will replace all carbon resistors and ALL caps. I found some of the R&Cs way out of spec. I already started the process.Waiting for parts...

    Other changes I did so far was to replace all known trouble maker semis such as the 2sc 458s on the PSU boards and the 2sa810s on the driver boards.
     
    Last edited: Jan 1, 2018
    ben_, Beau Geste, amr2 and 1 other person like this.
  3. Oilmaster

    Oilmaster Drillers go deeper Subscriber

    Messages:
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    Location:
    Paris & The Hague
    1 like for the first post only :cool:
     
    Mr. Yamaha and rottalpha like this.
  4. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
    Middle of Crook County
    LOL...I had them on hand and they were perfect fit ...but I am repenting :whip:
     
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  5. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
    Middle of Crook County
    here is how I am solving for the main cans issue on this B-1:

    IMG_20171210_140333739.jpg IMG_20171210_140405825.jpg IMG_20171210_140438517.jpg IMG_20171210_144122228.jpg IMG_20171210_144047206.jpg

    They are in there under the hood....in case someone in particular was wondering if they'd fit :p

    Lesson learned here is that if Saint Nick says he won't brig you the goodies you wished for, for Christmas and you want to play Christmas tunes on your B-1, you go get yourself a piece of Garrolite, some screws, a set of BadAss Rifa/Kemet caps and you make it your own big cans contraption.

    Edit: Still waiting for some Nomex paper to sandwitch between the chassis and the garrolite board...and most importantly between those screws and the chasis
     
    Last edited: Jan 11, 2018
    amr2 and Oilmaster like this.
  6. KingBubba

    KingBubba "Too Much Stuff" Subscriber

    Messages:
    10,004
    Location:
    Brooksville, Fl.
    Quite a machine. I have never seen the inside before today. It was great that it was designed as a modular amp. Your choices of changes made a lot of sense and will definitely help with the heat distribution that the original design did not do. The staggered resistors was simple, but will be, no doubt, effective. What a remarkable amp. Nice choices and nice job.
     

     

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  7. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
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    Thank you,
    yes, quite a machine indeed. Very complex circuitry but great acessibility under the hood, ...from the modular design perspective that is.
    Same goes for its matching pre.
     
  8. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

    Messages:
    4,226
    Location:
    Munich, Germany
    Nice work. And nice heat sinks. Do you have a source and part number to share? :)

    Cheers,
    James
     
  9. Mark B

    Mark B Yamaha Fan Subscriber

    Messages:
    5,605
    Location:
    usa
    Very nice! I recommend replacing the relay for any speaker output that you intend to use.
     
    cdfac likes this.
  10. Mr. Yamaha

    Mr. Yamaha Not so much Yamaha lately...

    Messages:
    898
    Location:
    Amsterdam Area, The Netherlands
    Great, will be following this :bigok:
     
    rottalpha likes this.
  11. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
    Middle of Crook County
    yes, they are the B-1 special edition. Plart number is #makeyourown.
    They come in a large sheet of copper format with sheers and instructions on how to make them so that when mounted on those TO-126 replacements, they do not touch the other components around and the B-1 chasis, .like other premade aluminum ones would :)

    Here is some of my stash:
    IMG_20171209_205836738.jpg
     
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  12. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
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    will most definetly do. Thanks Mark!
     
  13. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
    Middle of Crook County
  14. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,217
    Location:
    France
    Yes , I did
    no problem with them
    What are you looking for ?
     
  15. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
    Middle of Crook County
    Glad to hear that. I already pulled the trigger on some of these Bourns trimmers
    this looks like a perfect fit for the bias trimmers in the B-1. Not in stock at any other major retailers
     
    Last edited: Jun 11, 2018
  16. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
    Middle of Crook County
    @clinic-audio do you use axial or radial caps for this board?
    IMG_20171211_140309251.jpg

    my requirement is that they are rated to at least 105deg and that they are long life.
    I have a good choice of radials here in US. They would actually fit mounted vertically since they are short and fat. This requires some drilling into the board.
    Also available in EU are these badass Rifa/Kemet axials rted at over 20k hours @105deg:
    Screenshot_20171212-134134 (1).png
    on their way to me as we speak.

    did you find any other choices in the 105deg version?
     
    Last edited: Dec 13, 2017

     

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  17. 808_state

    808_state Well-Known Member

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  18. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
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    Yes, really nice indeed. Super good price considering the condition and that it went through maintenance already.
    I do see some rust on the end of those screws tho. This tells me there might be corrosion somewhere else on the chassis of that amp.
    You would need to be very cautions when buying from Japan. It is a hit or miss. Looking at the screws is a hint of possible hidden issues.

    I purchesd the B-1 (below) not to long ago from Japan and it is in outstanding physical condition. Absolutely no chorosion anywhere and I am almost certain I am the first person to pop the hood since it left the factory:
    IMG_20171120_215425186.jpg
     
    Last edited: Jun 11, 2018
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  19. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
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    you should keep an eye out here in the US as well. Sometimes they come up for sale. The one I am doing the "Quickie" on in this thread, I purchased on the auction site close to a couple of years back. It used to be owned by another AKer. That gave me more peace of mind then even buying from Hi-Fi Do :)

    This one I also picked up in the US.
    IMG_20171120_213558988.jpg

    a little rough on the edges, and it was repaired before. All original jewels tho.
    No UC/1 but with two B-1/UC-1s already, I kind of wanted a different garden veriaty. It was also convenient since it was local to me. I will endup making this my hot-rod daily driver.
     
    Last edited: Dec 12, 2017
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  20. rottalpha

    rottalpha Yamaholic Subscriber

    Messages:
    1,816
    Location:
    Middle of Crook County
    on tonight's menu: The filter board
    IMG_20171213_004132349.jpg IMG_20171213_004013642.jpg

    Replaced all lytics
    Replaced all ceramic capacitors. Not that they were bad but some were at the limits of their +20% tolerance...and because I had nice 1% silver micas on hand for all small pf values and Pannies polypropylene for the 10nF ones. For the Pannies, I am very grateful to someone that donated them to my stash.

    Replaced big fat resistors with 1% metal film
    Replaced the Relay
    one diode because had some oxidation on the leads
    replaced all BJT's with a992/c1845 awesome low noise alternatives

    Some notes here:
    Schematic calls for 2sa673A and for 2sc458s. For the c458s, I found 2sc1571s instead on the board. These are rated as low noise trannies. It looks like Yamaha ended up using something with even better noise floor than the 458s,.
    For hFE, the NPNs were in the ~390-430 hFE range, the PNPs were in the mid 100 range. The nice thing about the replacements I used is that I was able to match them for hFE across the line ~430, both, NPNs and PNPs
    BTW, has anyone noted the stock for the KSC1845s at the large US retailers??
    I suspect these will eventually end up going away..RC still has some on stock in UK...but not for long. They had about 2k in stock. A couple of hundred coming my way.

    Next for this board:
    I still have a few carbon resistors I want to replace...the ones with long leads in the photo. Waiting for parts.
    I am not sure I want to replace the green film caps. They test OK for capacitance. Does anyone have a reason to think I should replace the green film caps?
     
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