Yamaha B-2 find & minor repair questions

gonzothegreat

Super Member
Earlier this month I was at a hamfest where I had just sold most of my Pioneer & Sansui receivers to somebody with more time & storage space than I do when my buddy Steve called me over to his stand and asked if I was interested in a huge Yamaha amp. Never having seen a B-2 before it took a moment before I realized what was in front of me. He said the amp would come out of protection but he never finished the sentence. I couldn't remember if the B-2 was a VFET model but judging by the weight I knew this amp could be a major find (especially since I have a C-4 preamp). Even though I was supposed to be getting rid of stuff & not bringing anything new home (upcoming move), my gut said passing on it would haunt me for the rest of my days. A minute later (and seventy dollars poorer) I was the proud owner of a B-2 shlepping it the 100 feet to my car across my shoulders.

I didn't have time to test it until this weekend and it was worth the wait. Before I powered it up, I resoldered some minor cold solder joints around the fuseholders on the relay/PSU board. A quick examination of all other boards revealed no red flags so after a quick prayer to the silicon gods of the magic smoke, I hooked it up to a Phase Linear 2000 preamp, plugged it in and hoped for the best. Slowly bringing up the gain controls on the amp & preamp I was eventually greeted with music sans any sort of noise or distortion (not to mention smoke, sparks or flames). Both channels checked out OK aside from some slight noise on the speaker switches.

First question for $100 - the bias and offset pots are clearly labeled but I'm not sure about where the bias testpoints are. There is a three pin terminal in plain sight but I didn't see any markings on them.

Second question for $200 - what type of bulbs are used on the VU meters? I'm one for four and I suspect the good one is not long for this world.

Third and final question for $400 - the power switch cover/paddle is broken off flush with the faceplate. It still works and isn't in any danger of disintegrating and exposing line voltage. Any replacement suggestions or should I just live with it?

Maybe I never watched VU meters up close but the B-2's meters seem much more twitchy than those on my Kenny 700M & Phase Linear power amp.
 
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Congrats on the B-2! Sounds like it's in pretty decent shape, too.

I had a shot at one last week. I managed to track one down in San Diego that had a very vague listing title, something to the effect of "Power Amp for Sale". The guy wanted $100 for it. Believe it or not, it had been listed for something like 16 hours when I saw it. (woke up at 2:30 am, couldn't get back to sleep) I sent an email then called at 9 am, which I considered early enough but not too early. Turns out I was the second one to contact the seller, and the first was on his way over to check it out. Unfortunately, that was the end of that opportunity.

Ya win some, ya lose some. I figure if he'd put the make & model no. in the title it wouldn't have lasted more than a few hours. I have a good friend that lives in San Diego, who could have picked it up for me.

It's not as if I really need another amp, but that's one that I wouldn't pass up, especially at that price. I was thinking of eventually going to an active crossover on my NS-1000Ms, or perhaps even a tri-amp setup, and figured that would have been a good addition to the stable for that project. I'm in no hurry for the time being, however. I'll just wait and see what piques my interest in the future as far as amps go.

Enjoy your amp!

John
 
I would get that B2 completely refurbed to last another 30 years. Great score.
 
$70?! That's a GREAT score on a working B-2, even if it does have some minor issues.

Congrats!
 
First question for $100 - the bias and offset pots are clearly labeled but I'm not sure about where the bias testpoints are. There is a three pin terminal in plain sight but I didn't see any markings on them.

The 3 pins should be marked "E", "NS", and "CT" on the board. To adjust the bias you connect the meter between the "NS" and "CT" pins. Connect to "E" and "CT" to adjust the offset :thmbsp:

Awesome score! :music: :yes:
 
First and foremost, thank you for helping me rationalize my purchase. :p

Secondly thanks to EW for the leaksistors tip and other help he has thrown my way.

It was relatively clean inside and the electrolytics weren't visually stressed. They will still get replaced with Panasonic FCs once she lands on the bench. Other items on the to-do list include cleaning and regreasing the outputs and rebuilding the meter and PSU circuits.

Thirdly Vint Age wins the $100 prize of a Circuit City gift card for the correct answer on the bias & offset question. Whaddya mean they're out of business? Sunnofabitches...
 
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:nono: http://www.circuitcity.com/

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Someone bought their shingle and hung it out (internet only)

LOL

Congrats on the B-2 find, I'm jealous.
 
Congrats on the B-2!! Great pick-up for $70. Give her a little TLC and whala sweeet!!
 
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