Yamaha B-2 restoration journey

2SC458 affected type and should be replaced is 2SC458LG , this package :

2SC458.jpg

all the other don't need to be replaced , TO92 package :

2SC458-TO92.jpg
 
Thank you guys!

Right now I'm listing to the B-2 with my Castle Tay Speakers and sounds sublime.

I was expecting some lack of detail with all the sweetness it is famous for but with my Mojo dac the detail is totally there ***and*** also the sweetness! Truly awesome. After several years of having it on storage, after the recap, even when incomplete, I’m finally able to enjoy it!

I was able to tame the scratchiness with this equalization, done to achieve "A Weight" on the Audio Tool Android App while using a subwoofer with a cutoff at 50hz:

upload_2019-1-23_12-28-4.png

For what you have been sharing what we had to replace on my B2 are the:

2SC1452 and 2SA810

And the 2SC458 variation that I had was not the bad one… whelp, thank you for pointing it. Will remember for when I get my second B2!!! :beerchug:

What other elements would recommend updating?
 
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If your protection relays are still the originals, replacing them adds another plus to the sound quality. :thumbsup:
Thanks!
Any ideas about that weird equalization setting? My speakers are pretty linear with other amps... do you think updating the 2SC1452 and 2SA810 and protection relays will get more linearity on the sound?
 
For what you have been sharing what we had to replace on my B2 are the:

2SC1452 and 2SA810


All the B2 I have refixed were with original 2SA810 and 2SC1452 . They still work today as all my B2 . These TR fail because there is a problem in your amplifier . The B2 become bad but of course , it is not because of these TR !

One guy (who is not technician ) decide to replace them and evebody is doing the same (replacement) without understanding what they are doing .

You can replace everything inside your B2 if you want but, what for ?

If your protection relays are still the originals, replacing them adds another plus to the sound quality. :thumbsup: This is a good advise

Once your amplifier is working , the best thing tro do is to clean the switches on the front panel . 90% of B2 I have refixed get troubles with them . I am working (when I have time) on new board with new switches .
 
If you need that equalization only with that amp, is because it has something wrong. :idea:
 
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All the B2 I have refixed were with original 2SA810 and 2SC1452 . They still work today as all my B2 .

Agreed, by now I've refixed 7 B-2's and all but 1 still have the original 2SA810 and 2SC1452 TR's along with most of the other original semi's with no complaints from their owners that I know about; these are certainly very nice audio BJT's that have withstood the test of time and are still going strong.

This is a good advise

The 2 most significant sonic changes I've made to my own B-2 was to replace those relays with new ones and bypass the front panel switches.
 
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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.
Hi MiamiBoy,
i'm running thru forums to find the tip´s to restore my B-2. gladily i found your post about an execel list of what to change. Could you send it to me?
Leonardo
 
Small update here. I replaced the single turns with 500 mW multi turns and it's MUCH better. Bias spot on at 40 mV and DC offset spot on at 0 mV. Verry happy.

I went from 60 mV bias to 40 mV and it sounds much better. Less boomy, more seperation between instruments. But I still wonder whether imaging can be improved. The M-2 I had spreads the instruments all across the room, but with the B-2 the instruments are very near the speakers.

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I also changed the LED's to amber and made the lamp circuit series instead of parallel. I removed the jumpers / resistors and connected the LED's in series with wires and without mutilating the board. This was possible by removing 3 lamp holder pins and use the holes isolated to put the wires through. I added one multi turn pot to have the ability to change brightness. At day light it looked pretty close to original, but at night it was much too orange.

So, back to the drawing board.

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Could you please share the 500 mW multi turns code on mouser?
 
I got the relays replaced with new ones and bypassed the front panel switches. Much better now. Really enjoying it.

Question:
Is there something to gain in terms of sound quality by running it with higher bias that what the repair manual suggests?
I'm guessing that can bring more Class A power out of it...

My B2 after the recap runs really cool, almost no warm when touching the top.
 
I am curious as to why Yamaha chose the volume pot and speaker selection circuit they did. If a user wants to A-B two sets of speakers, the volume adjustment for each set of speakers would be welcome, so that they can be compared at as close to the same sonic level as possible. But the reliability of that circuitry, compared to a normal volume control and speaker selection circuit, isn't good. How often would most owners of this amp be comparing two sets of speakers anyway? Compared to how often one channel cuts out because of all the switch contacts?
 
Excellent Thread Mr. Yamaha. Any chance you could provide a complete BOM for the parts used in your Restoration? I am starting on a B-2 I recently acquired and can't seem to find much info on parts used to rebuild them.
 
How often would most owners of this amp be comparing two sets of speakers anyway?
some of us, more than you think

Compared to how often one channel cuts out because of all the switch contacts?
it does not have to be that way

If a user wants to A-B two sets of speakers, the volume adjustment for each set of speakers would be welcome, so that they can be compared at as close to the same sonic level as possible
true, you and "even out" less efficient speakers
But the reliability of that circuitry, compared to a normal volume control and speaker selection circuit, isn't good.
Yes, the original is nothing to write home about.
 
Excellent Thread Mr. Yamaha. Any chance you could provide a complete BOM for the parts used in your Restoration? I am starting on a B-2 I recently acquired and can't seem to find much info on parts used to rebuild them.

There are enough threads on B-2 rebuilds here for you to find about 95% of the parts information you need. The other 5% you can ask about. However, and this is coming from personal experience, replacing parts in a B-2 is risky business and you better have the discipline to not do anything on a hope and a prayer. There is a method to bringing the B-2 back up to speed, and you need to RTM and read all of the threads here until you are very clear on how to do this. You only have one chance to do it right or you may lose those vfets. Unless you have had a lot of B-2 repair experience, this is not the typical weekend recap project. Expect to spend many hours researching and learning before you even begin.
 
There are enough threads on B-2 rebuilds here for you to find about 95% of the parts information you need. The other 5% you can ask about. However, and this is coming from personal experience, replacing parts in a B-2 is risky business and you better have the discipline to not do anything on a hope and a prayer. There is a method to bringing the B-2 back up to speed, and you need to RTM and read all of the threads here until you are very clear on how to do this. You only have one chance to do it right or you may lose those vfets. Unless you have had a lot of B-2 repair experience, this is not the typical weekend recap project. Expect to spend many hours researching and learning before you even begin.

Thank you very much for the advice. I did spend quite a bit of time searching around for more threads on a B-2 Restoration to no avail. If you have some other threads that would help me out, could you point me in the right direction?
 
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