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B2

brinsmead said:
How are you and others addressing that issue or isn’t it a big concern?
Yamaha puts it so aptly when they say, "the B2 develops high internal temperatures"
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Yes, my PS boards have the sag in the middle and the regulator heat sinks were no longer glued to the PCB but the boards look good overall. I have a very good friend here who has 2 B-2's he restoring and both of his have the same thing happening. He came up with a creative way to secure the regs to the board as seen in the picture; interesting that your spare unused board has some of the sag built in and it doesn't say much for the quality of that board.

As you already know there's several sources of heat in the B-2. There's the regulators on the PS board and since the VAS is class A there are lots of hot transistors on the drive board. Also, there's the higher bias on the V-FET's that contribute. On a hot summer day you can feel quite a bit of heat radiating from it so I re-greased all the regs and outputs, I added some small heat sinks to the 4 transistors on the right side of the drive PCB's (they get quite hot), and for those really hot days I bought a laptop computer cooling plate that I place on top with some very quiet fans perfectly located over the case louvers. Fan technology back in the 70's was pretty basic and noisy so I'm thinking that's why Yamaha didn't go that route.

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My B-2 idling after being on for 3 hours in a 72” F ambient.

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Vintage,
very good, have you done yours the same ?
also would you be so kind as to post a close up of your mounting.

I'll copy that idea
Fans were very spartan in those years and the synchronous 240v (AU)variety and mainly in PA and Bass guitar valve amps and the like and mostly noisy.
This drive board is in perfect condition, it still retains that light pale hue.No sun tan there!
That temp is fantastic you could run that all day and night without any issues.
I've haven't looked at the circuit, but there is a vacant resistor spot on the drive board ?
Have you put blue leds in the meters ?
 
The difference between B2 Drive Boards'
posted by vintage ............ : NA06811

and the earlier Drive board here..... ; NA06747
 
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brinsmead said:
Vintage,
very good, have you done yours the same ?
also would you be so kind as to post a close up of your mounting.
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All my regs are done this way. It requires drilling 3 small holes through the PS board for the screws. I was lucky to have a small length of a tapped metal stripe that was just the right size to fit through the hole in the heat sink.

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Blue LEDs

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Thankyou Vintage, for all your input, very helpful.

One that could be a bit controversial to restoring purists
LED’s in the meters, you didn’t like the original setup ?
 
brinsmead said:
One that could be a bit controversial to restoring purists
LED’s in the meters, you didn’t like the original setup ?
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I installed the LED's in the original Stanley bulb holders so if I wish I can always revert. LED's make more sense to me because they last so much longer and they slightly reduce the overall heat. I like the blue LED's but the yellow ones in B-2 # 2 are closer to original and are my preference. I've also tried white and red just for fun.

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brinsmead said:
fullhouse of VFET's
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:tresbon:
 
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Its good to know that you didn't discard the original rubbers and you put them to good use,it would be hard to find these original stanley rubber lamps today.
I'm really keen on your yellow set up, thats just my own personal preference.
 
B2 re-capping

That’s handy LED info….good stuff.
It makes it a lot easier for any one wishing to do this mod.
Now I’ve started on this lamp project and the B2’s in pieces, I’ll recap the power supply board, Vintage did you chase down some good quality electro’s for your x2 …B2’s.
I see some black little beauties hiding in there.
 
brinsmead said:
Vintage did you chase down some good quality electro’s for your x2 …B2’s.
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Here's what I used:

C205 & 206 with Nichicon UPW2C101MHD
C209, 210 with Nichicon UPW1H100MDD's
C213, 214 with Nichicon UPW2A100MED's
C215 & 216 with Nichicon UHE2A151MHD's
C219 with a Nichicon UPW1E471MPD
C223 with a Nichicon UPW1C101MED
C221 with a Nichicon UVZ1C100MDD
C227 & C228 with Panasonic ECE-A1HN100U
I used some 2.2 uF films for C225 & C226 that I had laying around.
 
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Vintage,
you just make it so easy, you keep track of everything, you’re much better than any Yamaha spare parts manager,

One last thing, have you done any work on the drive boards?

As we know the B2 fairs well enough in the dry solder joint department, which is good, we don’t want any bad joints popping up on those drive boards with all that direct coupling.
 
brinsmead said:
One last thing, have you done any work on the drive boards?
Click to expand...

I went a little crazy on the drive boards. If you look closely at the picture in post #41 you'll see I wound up replacing almost every resistor for improved stability with new metal film types. The originals are carbon film which are better than average but since I enjoy this amp so much I thought I'd go all out on it just for fun. :D

Also, as I said before I added the 4 heat sinks to the transistors on the right side of the board and I replaced the trim pots and the 1 bi-polar cap.

As we know the B2 fairs well enough in the dry solder joint department, which is good, we don’t want any bad joints popping up on those drive boards with all that direct coupling.
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Yes indeed! While replacing the resistors I touched up every solder joint on the board. :thmbsp:
 
Vintage
I’m sure others will benefit from your rebuilding experience; it’s certainly made my path easier for re-capping and upgrading to high quality resistors.


The B2 remains an important part of our lives on so many levels, the build aesthetically brings together form and function as only the Japanese can.


Please check out US patent 3828230 Aug 6 1972 an invention by Dr Jun-ichi Nishizawa inventor of the VFET
 
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brinsmead said:
The B2 remains an important part of our lives on so many levels, the build aesthetically brings together form and function as only the Japanese can.
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Brins, it's nice to know that I'm not alone in my appreciation for this fine amp. :thmbsp:

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B2 power supply

In relation to power supply capacitors,
You may feel like increasing the capacity of electrolytic capacitors from time to time, but be careful.
You may destroy transistors by an excessive in-rush of current in particular constant-voltage power supply circuits and In relay speaker delay circuits where indiscriminate changing will alter the time constant
 
B2 Cooling

Array of Fans, This is a determined effort to keep a B2 cool

( Photo courtesy of a poster )
 
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