B2 vfets 2sj26 & 2sk76

Thankyou Vintage, Talk about Toshiba outs,I think Yamaha they must have had shares in Toshiba after and including the M2 nearly all outs were Toshiba manufactured.
Tha Pioneer Sa9800 with its Toshiba MT200 case outs sounded very similar to the Yamaha M2, TO3 outs
 
Besides being a wonderful sounding amp, the B-2 is practically bullet proof. Too bad the B-1 is so touchy. EchoWars has flat refused to work on a B-1 again :no:.
 
Yes thats right,the B2 is bullet proof,and as Vintage said , relays big issue.

Also the contacts in the input selector switch wear through the coating and become problematic.I did mention at one point that Yamaha supplied contacts to repair these switches.(many years ago of course)

The B2 is beautifully designed, with plug in drive boards, its where art meets glorious function
 
Yes thats right,the B2 is bullet proof,and as Vintage said , relays big issue.

Also the contacts in the input selector switch wear through the coating and become problematic.I did mention at one point that Yamaha supplied contacts to repair these switches.(many years ago of course)

The B2 is beautifully designed, with plug in drive boards, its where art meets glorious function

Yeah, I cycle my switches a few times before power on to make sure there are good contacts. I am seriously considering bypassing all the switches and volume pots on my B-2 just to give me confidence I have solid connectons. Can't be too hard to do this?
 
Yeah, I cycle my switches a few times before power on to make sure there are good contacts. I am seriously considering bypassing all the switches and volume pots on my B-2 just to give me confidence I have solid connectons. Can't be too hard to do this?

Actually, excluding the protection relay, there are only 2 switches in the B-2 signal path. One is on rear and selects between direct and capacitive input coupling and the other is on the front and selects between inputs A or B. The other switches simply route the 12V protection relay coil voltage for speakers A or B and speakers off or on so with that said it wouldn't be too difficult to bypass the input attenuators and switches for a more reliable signal path.

The protection relays are a more serious issue. They can be bypassed too but that's something I would never do for fear of speaker damage. The nicer answer for those would be to replace them with a DIY solid state relay arrangement ... but that would need to be carefully designed. :scratch2:
 
Besides being a wonderful sounding amp, the B-2 is practically bullet proof.

Yes indeed!

Too bad the B-1 is so touchy.

Having reconditioned both I'd say that the B-1 is definitely more complicated in its protection arrangement and adjustment setup. It has way more unobtainium than the B-2 given that it's an all FET amp and possibly the only one of its kind; therein lies its sonic magic but therein also lies its touchiness. When things go wrong they can really go wrong.

EchoWars has flat refused to work on a B-1 again :no:.

I wonder what the story is behind that? My guess is that he had an after repair failure in the -200V V-FET bias supply that resulted in big out of pocket $$$.
 
Yes indeed and if it is true I'll bet they'll be gone in no time ...

let me think that this is really strange ......See the picture we can see on their site and the picture I add to this message .....

WHat do you think about that ?? :scratch2:
 

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WHat do you think about that ?? :scratch2:

I never really thought they had any Yamaha 2SJ26 and 2SK76 parts to offer. I also think that the pair on the left in the picture have seen some serious heating judging from their discolouration. :yikes: :D
 
Actually, excluding the protection relay, there are only 2 switches in the B-2 signal path. One is on rear and selects between direct and capacitive input coupling and the other is on the front and selects between inputs A or B. The other switches simply route the 12V protection relay coil voltage for speakers A or B and speakers off or on so with that said it wouldn't be too difficult to bypass the input attenuators and switches for a more reliable signal path.

The protection relays are a more serious issue. They can be bypassed too but that's something I would never do for fear of speaker damage. The nicer answer for those would be to replace them with a DIY solid state relay arrangement ... but that would need to be carefully designed. :scratch2:

Yes, the A or B speaker switches are the big culprit. I've cleaned and lubed a few times but they still can be a little erratic. Rare but it does happen. Just click them once and all is good but something I don't want to fret about.

I've done a lot of maintenance and upgrades on my B-2 amp including replacing the relays. Also, multi-turn trim pots, all new electrolytic caps, upgraded signal wire, RCA terminals and speaker lugs.

It's not the most impressive looking little amp, but man do they make beautiful music!

 
Yours does look to be in very nice cosmetic shape. :thmbsp:

Yes I got lucky. I picked it up locally from the original owner who had it in storage since he moved up here to retire from SF in the 80s. I asked him if he had ever powered it up and he said no at the same time he flipped the switch. I almost grabbed for his hand to stop him but it was too late. To my amazement it powered up just fine but I was expecting to see smoke!

He was a cool guy who used to play in a rock band. Definitely a product of the 60s. Looked like a Dead Head. He restored electric guitars and had several dozens all over his home...
 
He was a cool guy who used to play in a rock band. Definitely a product of the 60s. Looked like a Dead Head. He restored electric guitars and had several dozens all over his home...

Perhaps he damaged his hearing while in the rock band to the point where he could no longer appreciate his B-2 ...
 
Just caught up with this thread. Must add my endorsement of the B2. Certainly a great amp.

Mine certainly needs a service. Really need to take the time to get this done right, by the right person. She's starting to play up. I might open it up and see if I have the "A" fets in it too..

When I FINALLY get this done, I'm still looking forward to a vfet shoot-out. Sony V Yamaha. I know, I know the Sony is a vfet hybrid, but its goin' to be good..

 
B2 FET output transistors

Hello !

Sorry but what "A'S " or non "A'S" transistors are you talking about ?

:scratch2:
 
let me think that this is really strange ......See the picture we can see on their site and the picture I add to this message .....

WHat do you think about that ?? :scratch2:

New Production in someone's garage in Asia. :D





Rumors has it that Hitachi Lateral MOSFET killed VFET in sonics and reliability.

Well, who killed the Lateral MOSFETs?
 
B2 output FET transistors

Hello !

I understand but if you want you can read my "service news" about B2

For your information the last transistors in B2 were :

2SJ38 ad 2SK98 :thmbsp:
 

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