Yamaha B-2 restoration journey

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

  1. Mr. Yamaha

    Mr. Yamaha Not so much Yamaha lately... Subscriber

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    So this Saturday I´m going to travel 1700 KM to pick-up a mint condition B-2, together with mint C-2 and mint T-2. All from first owner with manuals, so that's great. The C-2 will most likely go to someone else and I'm going to pair the B-2 with my C-4 to drive the NS-1000M's.

    I'v done a lot of reading about the B-2 and there are 100's of ideas on what parts to replace to protect those VFET's before putting it into rotation. I'm going to use the B-2 daily in my main system. It will be on for at least 4 hours every day (is that even a problem?).

    I don't want to do complete overhaul just yet, but I want to replace everything that is mandatory to protect those VFET's. According to the seller, the B-2 plays completely fine at this moment.

    What I think I should replace / do:
    • All electrolytics on the power board
    • At least 2 Zeners on the power board (why not all?)
    • All 2SC458's (also meter board)
    • 2 BP electrolytics on the driver boards
    • All possibele VD1212's with two 1N4148's in series
    • Protection relais
    • Clean all switches and pots
    • LED upgrade (has nothing to do with VFET protection)
    • Replace the binding posts (has nothing to do with VFET protection)
    Is this all it takes? Any other suggestions or corrections?

    IMG_1478887850_11979.jpg
     
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  2. Mr. Yamaha

    Mr. Yamaha Not so much Yamaha lately... Subscriber

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    Last edited: Nov 16, 2016
  3. rottalpha

    rottalpha Yamaholic Subscriber

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    Nope.
    They are not the correct voltage rating and temp rating of only 85deg
     
  4. Mr. Yamaha

    Mr. Yamaha Not so much Yamaha lately... Subscriber

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    Crap, I did miss the 50V part. But it need to be 105 deg? I've seen 'everybody' here on AK using the Nichi KG 22000 uF, which are always 85 deg. rated.
     
    Last edited: Nov 16, 2016
  5. MiamiBoy

    MiamiBoy Active Member

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    I have completely refurbished two B2's and spent a lot of time consolidating notes from many threads on this subject. I compiled an Excel sheet of very component I replaced, the new part# and their location in the amp. Will also share some key pictures if you like. Some I already posted in previous threads.

    If you are interested, PM me your email and I will send you some items that you may find helpful.

    I don't know your history or how familiar you are with amp work but please familiarize your self with the many warnings in other posts on how to protect the VFETs and discharge the caps before doing any work.
     
    Last edited: Nov 16, 2016
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  6. Mr. Yamaha

    Mr. Yamaha Not so much Yamaha lately... Subscriber

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    Thanks, I'll send you a PM.
     
  7. rottalpha

    rottalpha Yamaholic Subscriber

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    You are correct. The Nichi golds seem to be the preferred choice, but not mine. For this particular amp and use, the 85deg temp rating is a deterrent for me.
     
  8. Mr. Yamaha

    Mr. Yamaha Not so much Yamaha lately... Subscriber

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    Which ones do you prefer? I've seen some 105 deg. 22.000 uF snap-ins of Cornell Dubilier, but I'm not sure whether the snap in pins can get aligned properly with the original holes.
     
  9. rottalpha

    rottalpha Yamaholic Subscriber

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    You only need to align 2of the 4 pins, in the case of CDE. The CDE would fit. I have personally tested them.
    I prefer the Panni ECE, but they are harder to get as they are being discontinued.
     
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  10. Beau Geste

    Beau Geste Super Member

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  11. rottalpha

    rottalpha Yamaholic Subscriber

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    The original lytics were rated at 85deg. Most have by now drifted substantially from their capacitance rating. The primary reason is heat, second is age.
    If there is one area where the b-2 can be improved, is the physical layout/arrangement of the psu. Since that is a not so easily attainable, substituting the original components with higher temp rating ones, is a logical measure.
     
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  12. Beau Geste

    Beau Geste Super Member

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    Yes , I am agree . 105deg instead of 85 not change nothing . I mean about the capacitance and voltage.
     
  13. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    Hello M.YAMAHA

    What I think I should replace / do:
    • All electrolytics on the power board YES
    • At least 2 Zeners on the power board (why not all?) YES (not all)
    • All 2SC458's (also meter board) many are doing this , this is silly not necessary the "bad 2SC458 is the LG type ONLY no other one !
    • 2 BP electrolytics on the driver boards YES
    • All possibele VD1212's with two 1N4148's in series 2 1N4148 are not the right sub for VD1212 (varistor) and this is not necessary but many does it (not me)
    • Protection relais YES of course
    • Clean all switches and pots you will have a very long process and difficult work for the speaker selector switches
    • LED upgrade (has nothing to do with VFET protection) if you like it
    • Replace the binding posts (has nothing to do with VFET protection) if you like it
     
  14. Mr. Yamaha

    Mr. Yamaha Not so much Yamaha lately... Subscriber

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    Thanks Clinic. But, are there substitutes for VD1212's?

    And what about the main filter caps or other components prone to failure?

    I've also seen some guys replacing the rectifier diodes with Fairchild Stealth 600V 30A diodes.
     
  15. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    Thanks Clinic. But, are there substitutes for VD1212's? are they defect ? Why do you want to replace all your VD1212 ??
    VD1212 were made by NEC (YAMAHA part number IF000770)
    Perfect sub for VD1212 is MV12 made by OIZUMI (YAMAHA part number IF000790)
     
  16. rottalpha

    rottalpha Yamaholic Subscriber

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    MV12 is not readly available either. Maybe that it is why is being replaced by 2 x n4148's
     
  17. Mr. Yamaha

    Mr. Yamaha Not so much Yamaha lately... Subscriber

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    No they're not broken, but are known for causing trouble.

    True.

    And what about the rectifier diodes, are they reliable?
     
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  18. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    MV12 is not readly available either.
    Ask your YAMAHA parts department
     
  19. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    No they're not broken, but are known for causing trouble.

    hum ...Internet know the true ? I strongly recommend you to not replace them if they are not defective . I made 5 B2 this year and NONE was needing VD1212 replacement . I work on old YAMAHA product since 40 years and I think it is fair enough to tell you this advise . Do what you want but if you compare datasheet of 1N4148 and VD1212 you will see that this is not really the same part . When you use 2 1N4148 in serie , do you select them ?
     
  20. clinic-audio

    clinic-audio all on YAMAHA untill 1990

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    Regarding electrolytic capacitor , I bought them at "parts connexion"
    They are longer than original type so you need to adjust the rear cover (above transformer wires)
    B2-capacitor-pcb-01.jpg B2-capacitor-02.jpg B2-capacitor-pcb-03.jpg B2-capacitor-pcb-04.jpg B2-capacitor-pcb-05.jpg B2-capacitor-pcb-06.jpg
     
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