B2

brinsmead

Active Member
Vintage,

Customers that didn't wish to fork out $328 dealer cost for a matched output pair.

The 2SJ26A (which had a dealer price of $78.69 for a single unit but not available separately)

I did output rebuild a B2 with Yamaha VFET 2SJ38 and the complementary VFET 2SK98 at that time, this was an option offered by Yamaha Au (Rose Music) in the 80’s.at $10.60ea

I assume later Yamaha Japan would have destroyed any loose stock of the paired VFET’s they had.

This guy has some NOS Yamaha 2SJ26 and 2SK76, currently avail at $80 for a pair, not bad considering. which might have escaped the crusher. (Ebay polida2008 )

regards B
 
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This guy has some NOS Yamaha 2SJ26 and 2SK76, currently avail at $80 for a pair, not bad considering. which might have escaped the crusher. (Ebay polida2008 )

Thanks for the heads up! Too bad these weren't like BJT's where you could just buy a pair and pop them in and be good to go and too bad that Yamaha didn't do like Sony and batch them into different rankings codes that they marked on the case along with the part numbers ...
 
So there isn't a good way to match up V-fets for the B-2, unless they come from an existing unit?
 
In relation to the B2 to those that are interested, from a service related point, the main issues with the B2 in the early years , on and coming off warranty was the switches. Yamaha would supply complete switch assemblies with out issue for any that became noisy with oxidised contacts.
In later years when switches became unavailable from Yamaha they supplied internal switch contacts which were priced individually per contact and with their own part number. (albeit expensive about $100 cost per switch bank)
This was a relief for many a customer that had repeated cleaning.
 
the main issues with the B2 in the early years , on and coming off warranty was the switches.

And likely still is a big issue today for anyone buying a used B-2. It took a serious cleaning effort to get mine to where they're behaving ... most of the time; the most problematic being the input selector switch. I usually work it a few times before I sit down for a listen. The speaker on/off and A/B switches are switching the protection relay coil current and have been less of an issue on mine. I was fooled by them at first because the protection relay contacts were soooo bad. New relays fixed that real well. :tresbon: :thmbsp:
 
Thats absolutely correct N ,The input selector switch was the biggest offender.I rebuilt a few of those front panel switches, replacing the plastic segment contacts when the complete switch became unavailable
regards R
 
Yamaha B2 Switches

To be quite honest still to this day I cant quite get a handle on how these switches deteriorated so quickly, I can remember receiving many new switches from Yamaha and these were generally supplied loose,( not sealed packaging) that the legs on them were so tarnished (black almost) and they looked years old, so much so that I’d sample a couple and keep the best ones back and wrap them in plastic for a future jobs.
I’d go so far as to say they were flawed before they even got into the B2’s.
I never saw tarnishing to that degree on new Panasonic Ganged Vol Controls in C2a
 
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And the input attenuation controls are kind of low grade too. :thumbsdn:

If it weren't for the fact that this amp sounds so darn good I would have scrapped it a long time ago. Instead I found a second one. :D
 
Yamaha B2 Switches and other jotterings

Don’t get me wrong, still one of the best amps of all time, like you, I wouldn’t sell mine for all the tea in China.
I don’t suppose you can blame Yamaha, say for a company like Alps which made a lot of what had the potential to be very high quality switches and pots to the Industry to slip up.
I digress here , Yamaha were a very dedicated customer orientated company that would do almost anything to make you happy, I remember ordering a top cover for a Yamaha C4 before Christmas one year and it arrived close to the holidays.
It was packed well but creased on top and was not a lot of value, Yamaha air freighted at their expense another to me within a few days and landed right on Christmas. They were very, very apologetic and said that this replacement cover was taken off one of their personal museum stock. I was very impressed.
The 70’s and 80’s were a great time for the big Japanese Amp makers each one trying to upstage the other with technological breakthroughs. Hi Fi was big business and the buying public were treated to some very fine gear.
 
still one of the best amps of all time,

Yes indeed! I'm always surprised at how little interest and discussion there is about the B-2 as compared to Yamaha's other PA's; on the other hand I'm grateful because I was able to snag mine for a very reasonable dollar.

They were very, very apologetic and said that this replacement cover was taken off one of their personal museum stock. I was very impressed.

Amazing! Where on earth would you find that kind of support today?

The 70’s and 80’s were a great time for the big Japanese Amp makers each one trying to upstage the other with technological breakthroughs. Hi Fi was big business and the buying public were treated to some very fine gear.

And today we can still enjoy those wonderful amps at a fraction of the price and a little bit of TLC.
 
The Quality can be seen here in the Yamaha C4 input, Alps-Wafer Switch and to right the Quality of Noble B2 power Switch with the replaceable Petrick 240v Switch Back
 
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B2 Input Switches

A complete new B2 input selector switch, which has visibly tarnished legs

A new contact set for repairing these switches has also tanished legs but not to the same degree as the complete new switch also the tarnishing is extended to the fixed contacts
 
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Those are nice to have in reserve. I'll bet they'd clean up real well with a good scrubbing of the right DeOxit product. :thmbsp:
 
B2 vfet

In relation to the output VFET Yamaha 2SJ26 and 2SK76.

In the B2 early versions, the 2SJ26 and 2SK76 were fitted, later versions of the B2 had 2SJ26A and 2SK76A fitted as standard,
These later versions with the A prefix were rated , vDS=150vdc.
2SJ26 and 2SK76 were rated, vDS=200vdc
The first series were a more robust VFET
Vintage what's in your 2 x B2’s?
 
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Vintage what's in your 2 x B2’s?

Interesting info about the A's and non A's. I always wondered what the difference was. Too bad there isn't a nice clear version of the data sheet out there for these parts. The only ones I've seen is the one I've attached ...

My first one has the A V-FETs fitted to the all black heat sinks c/w mica insulators. My second has the non A's fitted to the black heat sinks with the special blue painted surface and no mica insulators.

attachment.php
 
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Deoxit is just a nice try. I clean these switches in an ultrasound bath with "Cillit Bang" anti rust & limescale. Then I rinse with distilled water, remove the liquid inside with compressed air, remove any residues with isoprop. and dry it with an hair dryer. The metal parts are shiny like new after this treatment.
 
I clean these switches in an ultrasound bath with "Cillit Bang" anti rust & limescale. Then I rinse with distilled water, remove the liquid inside with compressed air, remove any residues with isoprop. and dry it with an hair dryer. The metal parts are shiny like new after this treatment.

Yes indeed. I've often wished I had access to one of those. :thmbsp:

Why not just bypass the switch. It seems unnecessary.

I connect my preamp to one B-2 input and the variable output from my CD player to the other input so the switch is still useful to me since the variable output from the CD player doesn't need any preamping; it sounds so much better that way.
 
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