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Yamaha B2 - the "why" and the "how" of a comprehensive rebuild

I hear you brother...I am getting blind with glasses on.

Are you saying that after you rebuilt the vu-meter board, the amp works again but: after power off, the caps on the left side of the PSU discharge faster than those on the right, if the vumeter board is connected?

If yes, that is expected behavior and that is how your amp worked before. The vu-meter +/- 25v supply piggy-backs on one side of the +/- 59v rails. I know, silly for Yamaha to save pennies this way...look at those two fat voltage drop resistors on the vumeter board, and trace them back to the feed, and it will all make sense.
 
Perhaps the meter board is not the problem, what I’ve observed is that what ever side I connect the right driver board to (60v) that side meter pegs momentarily at shut down while the left driver board does not.
 
Soundslave said:
Perhaps the meter board is not the problem, what I’ve observed is that what ever side I connect the right driver board to (60v) that side meter pegs momentarily at shut down while the left driver board does not.
Click to expand...
So the problem follows one of the driver boards to either left or right vumeter??
 
Yes at shut down, and the meter that is connected at the opposite G to S shows 65v as the meter pegs. Doesn’t this indicate both + and - at turn off across G to S?
 
Are you measuring 65v across the output of the amp? The meter is not connected at gate and source of the vfets.
Having a difficult time understanding what you are describing.
 
Sorry for the confusion. My DMM goes from the 32v to 65v at shut down between the opposite G and S. Whatever side I connect that driver board to the amps meter on that side will try to peg at shut down.
 
Soundslave said:
Sorry for the confusion. My DMM goes from the 32v to 65v at shut down between the opposite G and S. Whatever side I connect that driver board to the amps meter on that side will try to peg at shut down.
Click to expand...
Did you test the board individually?
Make sure your front end ground is connected otherwise everything will be wonky.
 
Soundslave said:
The one at the sink is connected to the chassis via a jumper and the board has a good ground connection
Click to expand...
That’s not answering my question. I cannot see or know how you are testing your boards.
Confirm that there is nearly zero resistance between your signal input ground and the main center ground on the PSU.
 
Hello B2 fans

I recently got a B2 m.
It's a bit beat up, worn out on the front, the button contacts are faulty, they crack.

But the B2 itself works well, despite its faults.

I live and work in Germany, near Stuttgart.

I've already contacted Peter (rottalfa) and cliniqueaudio.

But I'd still like to know where there is a B2 owner near me, maybe one that has already been refurbished, partly or completely B2 t.

Do you know a mechanic nearby or further away who can refurbish/restore B2 models?

Maybe in Hungary, where I'm from?

There's a Hifi service nearby that's been operating since 1985, Yamaha and other brands, official service partner.

HIFISERVICE Schmaehl in Herxheim - Wir reparieren: Boston,Denon,Yamaha,Onkyo,Kenwood und jede Menge andere Geräte! 76863 Herxheim bei Landau.

I look forward to hearing from you, even on my WhatsApp +491601627324

Have a nice day to the team : Ferenc


Üdvözlöm a B2-es rajongókat!

Nemrég kaptam egy B2 m-et.
Kissé leharcolt, eleje kopott, a gombérintkezők hibásak, repednek.

De maga a B2 jól működik, a hibái ellenére.

Németországban élek és dolgozom, Stuttgart közelében.

Már felvettem a kapcsolatot a Péterrel (rottalfa) és a cliniqueaudio-val.

De még mindig szeretném tudni, hogy hol van a közelemben B2 tulajdonos, esetleg olyan, akit már felújítottak, részben vagy teljesen B2 t.

Ismersz a közelben vagy távolabb olyan szerelőt, aki fel tud újítani/helyreállított B2 modelleket?

Talán Magyarországon, ahonnan én származom?

Van a közelben egy 1985 óta működő Hifi szerviz, Yamaha és más márkák, hivatalos szervizpartner.

HIFISERVICE Schmaehl in Herxheim - Huzaljavítók: Boston,Denon,Yamaha,Onkyo,Kenwood és jede Menge andere Geräte! 76863 Herxheim bei Landau.

Várom válaszát, akár a WhatsApp-on is: +491601627324

Szép napot kívánok a csapatnak: Ferenc
 
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Hi all!

While selecting replacement parts based on the recommendations in this thread, I noticed that some of them were out of stock. What transistors would you recommend as replacements of KSC3503, KSA1381, KSA733?

tr.png

Also, which of these resistors are fusible? Did I choose the right type of new resistors?

res.png
 
US7IGN said:
What transistors would you recommend as replacements of KSC3503, KSA1381, KSA733?
Click to expand...
MJE340 for KSC3503 AND MJE350 FOR KSA1381 —> Close but not identical
KSA1013 for KSA733 —> note that this is also close but not identical. There may be other choices, I haven’t looked closely. The compliment for KSA1013 is KSC2383 if needed. The data sheet doesn’t say so explicitly but the data is identical for both except for Cob (output capacitance)

These are in stock at Mouser. Check the pin out before ordering.
 
bulejko said:
Hello B2 fans

I recently got a B2 m.
It's a bit beat up, worn out on the front, the button contacts are faulty, they crack.

But the B2 itself works well, despite its faults.

I live and work in Germany, near Stuttgart.

I've already contacted Peter (rottalfa) and cliniqueaudio.

But I'd still like to know where there is a B2 owner near me, maybe one that has already been refurbished, partly or completely B2 t.

Do you know a mechanic nearby or further away who can refurbish/restore B2 models?

Maybe in Hungary, where I'm from?

There's a Hifi service nearby that's been operating since 1985, Yamaha and other brands, official service partner.

HIFISERVICE Schmaehl in Herxheim - Wir reparieren: Boston,Denon,Yamaha,Onkyo,Kenwood und jede Menge andere Geräte! 76863 Herxheim bei Landau.

I look forward to hearing from you, even on my WhatsApp +491601627324

Have a nice day to the team : Ferenc


Üdvözlöm a B2-es rajongókat!

Nemrég kaptam egy B2 m-et.
Kissé leharcolt, eleje kopott, a gombérintkezők hibásak, repednek.

De maga a B2 jól működik, a hibái ellenére.

Németországban élek és dolgozom, Stuttgart közelében.

Már felvettem a kapcsolatot a Péterrel (rottalfa) és a cliniqueaudio-val.

De még mindig szeretném tudni, hogy hol van a közelemben B2 tulajdonos, esetleg olyan, akit már felújítottak, részben vagy teljesen B2 t.

Ismersz a közelben vagy távolabb olyan szerelőt, aki fel tud újítani/helyreállított B2 modelleket?

Talán Magyarországon, ahonnan én származom?

Van a közelben egy 1985 óta működő Hifi szerviz, Yamaha és más márkák, hivatalos szervizpartner.

HIFISERVICE Schmaehl in Herxheim - Huzaljavítók: Boston,Denon,Yamaha,Onkyo,Kenwood és jede Menge andere Geräte! 76863 Herxheim bei Landau.

Várom válaszát, akár a WhatsApp-on is: +491601627324

Szép napot kívánok a csapatnak: Ferenc
Click to expand...
Hello @bulejko
maybe I can help you.
I'm from Germany, and last year I serviced a Yamaha B-2 for @Allribbon10p .
At the moment I prepare to service my Own B-2 as well.
There's just one problem: I don't have much time to work on devices anymore because I study in parallel to my normal work.
If you want you can contact me via pm.
Regards
Alonia
 
Inspired by this thread, Peter's generous advice and the accomplishments of other B-2 lovers, I found a fully-serviced B-2 that I was going to fully restore following what's been shown in this thread. I contacted Peter and bought his full set of PCBs with JFETs, and even found 4 new, unobtaineum Nichicon KG Gold Tune 22000µF 80V caps.

Plans changed and my B-2 has found a new home. I asked Peter if I could pass his creations onwards and he gave his consent. If anyone is interested, please let me know as I would much rather they go to an AK B-2 lover who's on and has been through this thread. I will offer them outside of AK starting July 2026.

Thanks.
 
SL01 said:
Inspired by this thread, Peter's generous advice and the accomplishments of other B-2 lovers, I found a fully-serviced B-2 that I was going to fully restore following what's been shown in this thread. I contacted Peter and bought his full set of PCBs with JFETs, and even found 4 new, unobtaineum Nichicon KG Gold Tune 22000µF 80V caps.

Plans changed and my B-2 has found a new home. I asked Peter if I could pass his creations onwards and he gave his consent. If anyone is interested, please let me know as I would much rather they go to an AK B-2 lover who's on and has been through this thread. I will offer them outside of AK starting July 2026.

Thanks.
Click to expand...
try putting an ad on Barter Town, if you have not done so already
 
Moving the VU meter lighting discussion here.
As discussed elsewhere, I am happy with improving the lighting for the VU meters using strip LEDs. My initial try was with the C-1 VU meters, where I used 5v LED option for various reasons not relevant here.
For the B-2 and UC-1 the original incandescent VU meter light supply is about 11.4VDC so technically a 12v rated LED strip with a current limiting resistor would be more or less a drop in.
Here is what I found straight from Amazon:
image.jpg

The strip is 5mm wide vs the 2.7mm wide strip I used for the C1.

Here is both of them side by side

image.jpg
image.jpg
Note: The 12V rates strip above powered at 11.4Vdc as available with the B-2 PSU.

The 3000k temp seems to be a good fit as seen with the C1 VU Meters here:
IMG_1212.jpegIMG_1211.jpeg


And here:

More to come with a B2 or UC1 mod coming soon.
 
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