B2

[brinsmead]

Thankyou so much for your home work rottalpha, I’ll order 4 of the Nichicon KG, snap in type ; Question, how do they line up with existing PCB mounting holes?

It might be the last big job I’ll do on the B2.

...........I’m curious to know if any one else is still running on the original 18000uf’s ,after all these years of use, what was their life again, 1000hrs perhaps ? if that’s the case there well due to be changed.

I’ll do an ESR and check their capacitance on mine just for interest.

My B2 serial number is in the high 9000 ( after 5000 s/n they had the mica washers under VFets and the “A” version VFets ) not necessarily better VFets.

One of the last 240 v versions bought into Australia purchased 1979

thankyou again guys, that's a big help

 

[rottalpha]

Hi Brins,
when you said 42 years I lost track of time...or didn't bother with the math. The one I have in original condition is in the 1000 series. Since the count starts from 1000, it is one of the first few hundred made, so it would be right around 1976 or 45 years old. I actually have more than one of that age that runs OK, but this in particular seems to have "low miles" so I keep it for reference to R&D my modes.
About the old caps,
if yours are testing higher than 14,000uf, I would be very surprised. Most don't, especially if the amp got a taste of that higher mains voltage.
The KGs will fit right in the original PCB, albeit, you would need to "stretch" the PCB rectangular holes towards each other just a tiny bit. A small file does the job just fine. Some will suggest to trim the caps pins, but I do not do that.
You will need to reroute the right channel transformer primary wires. I prefer to do it through the bottom.
If your fuse holders are laid horizontally, on top of the shield plate, you will need to move them to the rear side so that they are mounted vertically, where the fuse holder mounting screw would point towards the top of the new caps, no the side. You will need to trim the fuse holder screws a few mm, or use shorter screws.
It all sounds more complicated than it actually is.


Th fuse holders need to go this way, not on top (where you see the alternative mounting point.

 

[brinsmead]

Thankyou rottalpha for the detail...I'll use that in my rebuild, yours looks 'so' good.
Its nice to see its original format been kept, that fit is great......well done...thats the best Ive seen.

I'm not entirely convinced about the speaker terms, but I'm more conservative in keeping original.......thats just me

If you're there 'VINTAGE' ; have you replaced your 18000uf in the B2 ?

 

[Vint Age]

Thankyou rottalpha for the detail...I'll use that in my rebuild, yours looks 'so' good.
Its nice to see its original format been kept, that fit is great......well done...thats the best Ive seen.

I'm not entirely convinced about the speaker terms, but I'm more conservative in keeping original.......thats just me

If you're there 'VINTAGE' ; have you replaced your 18000uf in the B2 ?

Brins, like you I tend to be more conservative in my approach but I love the beautiful work Rott is doing to his B-2's and his other amps!

I still have one B-2 with the original main caps that I've been using daily in a second setup for the last 4 months. It's had all of the other electrolytic caps changed several years ago but other than that it's pretty much stock. To my ears it sounds just as wonderful as my other B-2 that's had a major overhaul and I'm not expecting the main caps to fail in it anytime soon.

After servicing quite a few of these it's my feeling that if your B-2 has lived a well ventilated and respected life, as I expect yours has, the main caps are likely still fine given their quality. With that said, YMMV; I always offer replacement of them as an option since by now I've seen some B-2's that have lived a hot life as evidenced by the condition of other components under the hood. Also, I have replaced them in my other B-2's just to be prudent.

As far as capacitance goes, like Rott says, all of the ones I've replaced so far were on the low side. Here are the last 4 I replaced. For what it's worth they appear to be in good overall physical condition ...

 

[rottalpha]

Brins, like you I tend to be more conservative in my approach but I love the beautiful work Rott is doing to his B-2's and his other amps!

I still have one B-2 with the original main caps that I've been using daily in a second setup for the last 4 months. It's had all of the other electrolytic caps changed several years ago but other than that it's pretty much stock. To my ears it sounds just as wonderful as my other B-2 that's had a major overhaul and I'm not expecting the main caps to fail in it anytime soon.

After servicing quite a few of these it's my feeling that if your B-2 has lived a well ventilated and respected life, as I expect yours has, the main caps are likely still fine given their quality. With that said, YMMV; I always offer replacement of them as an option since by now I've seen some B-2's that have lived a hot life as evidenced by the condition of other components under the hood. Also, I have replaced them in my other B-2's just to be prudent.

As far as capacitance goes, like Rott says, all of the ones I've replaced so far were on the low side. Here are the last 4 I replaced. For what it's worth they appear to be in good overall physical condition ...

View attachment 2180727 View attachment 2180728 View attachment 2180729 View attachment 2180730

thank you for the compliment Vintage. It matters a lot when it comes from you

The last four you replaced look to be in good condition indeed. It is hard to find then that way. I search over 60 caps and so far I only found 5 to be over 17,000uf.
Four of them will be going back into another stock unit and one will be going to R&D.
The majority of the other caps were 14000uf or below.

note, I recently went through about 8 sets of those KGs. All 22,000uf on paper, but all ~19,000uf on the bench ....that is a good thing for the B-2.

 

[rottalpha]

I'm not entirely convinced about the speaker terms, but I'm more conservative in keeping original.......thats just me

That is a very valid observation. Not everyone is appreciating the new speaker posts and rear RCAs, but I have to admit that the majority of people do and that is because of the functional convenience the modern speaker posts offer....but they are a PITA to install since the mounting plate needs to be machined for decent size posts to sit properly.

 

[Vint Age]

note, I recently went through about 8 sets of those KGs. All 22,000uf on paper, but all ~19,000uf on the bench ....that is a good thing for the B-2.

These are the beauties I've been installing.

 

[brinsmead]

Most appreciative, my Canadian and American and Aussie friends, this a great help and you guys make it so easy for any one with a small amount of electronic knowledge and is a bit game to replace these electro’s, this simple explanation is a great help guide and you’re never to old to learn a few new tricks

I’d be interested if any of you guys had a mains switch failure issues ?

( May be the difference, between the US 110vac and UK/AU 240vac models would possibly be a typically a higher voltage rating on the 240vac switch contacts and high current on the 110vac US models. ) but leaving that aside, the lever switch and layout of the switch back is different on both, both will fit mounting, both appear to come from different manufactures, finding a replacement is difficult.

Has anyone had a to replace a mains switch and if so with what ?

Happy Easter Guys take care and God bless

 

[rottalpha]

Most appreciative, my Canadian and American and Aussie friends, this a great help and you guys make it so easy for any one with a small amount of electronic knowledge and is a bit game to replace these electro’s, this simple explanation is a great help guide and you’re never to old to learn a few new tricks

I’d be interested if any of you guys had a mains switch failure issues ?

( May be the difference, between the US 110vac and UK/AU 240vac models would possibly be a typically a higher voltage rating on the 240vac switch contacts and high current on the 110vac US models. ) but leaving that aside, the lever switch and layout of the switch back is different on both, both will fit mounting, both appear to come from different manufactures, finding a replacement is difficult.

Has anyone had a to replace a mains switch and if so with what ?

Happy Easter Guys take care and God bless

View attachment 2181623 View attachment 2181624

I have.
What is the issue with your switch?
is it mechanically difficult to operate? That could lead to this:


if it is not the mechanics, do you have poor contact?
If yes, the switch can be cleaned. These are snap switches and are very robust. It is unlikely that it needs replacement.

if for any reason you find signs of significant electrical damage inside the switch, you need to check those spark suppressors.

Then there is also the choice of adding an thyristor switch, but I honestly did not find a good case for that yet with the B-2.

 

[Vint Age]

That could lead to this:

I guess I've been lucky so far.

 

[rottalpha]

I guess I've been lucky so far.

I found a few units with the switch mechanically seized up. A couple of drops of mineral oil on that brass bushing, makes it work like new....unless someone already tried to make it work using brute force. That I found to be the case in a couple of occasions.....you see the results of the brute force "solution" in that photo.

 

[brinsmead]

Thanks for your reply Guys, well I had to throw the mains switch a few times to get her up and running,
( bit of arcing inside)
Now I've got the sweet spot....I've left the power switch on permanently and powered her up with a power board.......looking at the pics, the switch back is definitely not as robust as your US version.
.rottalpha..did you repair that switch shaft satisfactorily ?

 

[brinsmead]

Vintage, thankyou for your informative reply on your caps, I found all this very interesting...Ive cut and pasted all this in a file for future reference.

 

[rottalpha]

Thanks for your reply Guys, well I had to throw the mains switch a few times to get her up and running,
( bit of arcing inside)
Now I've got the sweet spot....I've left the power switch on permanently and powered her up with a power board.......looking at the pics, the switch back is definitely not as robust as your US version.
.rottalpha..did you repair that switch shaft satisfactorily ?

nope,
had to be replaced...with an original switch.

Yep, the EU/AU switch looks to be different. post some photos of your switch.
I am thinking you can clean it but once cleaned you might want to consider a thyristor switch.

 

[clinic-audio]

Hello

B2 switches start to be a problem with age :
- Petrick type (for US market and Europe market ) are not so strong than Japanese model

here are some pictures

B2 Petrick model used for power ON/OFF switches



on this picture we can see the broken leg



Strongest Japanes models are like this :



But sometimes some power switches makes bad contacts inside the body

 

[clinic-audio]

let's see how are the contacts inside :



and a little bit closer



after some work , we have



and how are the contacts bars ?



After some work on them :



Then you just have to rebuilt the switch and re-install it with 2 new spark killers cap and your power switch will work like a new one

a contacts spray will not do that , never .

 

[brinsmead]

rottalpha, thankyou...........

clinic audio has trumped me with the pictures they are spot on.

Good job cleaning up the Japan/USA type switch clinic audio and the pictures......Mine is the Petrick type, pretty weak switch back, a burnout waiting to happen.

 

[rottalpha]

The EU and AU (230v-240v) are the same.
The Japan and US models (100v-117v) are the same,

I have never seen a US/Japan switch to look that deteriorated inside. @clinic-audio , there must have been something wrong with the spark suppressors on those units.

 

[rottalpha]

rottalpha, thankyou...........

clinic audio has trumped me with the pictures they are spot on.

Good job cleaning up the Japan/USA type switch clinic audio and the pictures......Mine is the Petrick type, pretty weak switch back, a burnout waiting to happen.

then I guess your unit is a good candidate for this:

 

[brinsmead]

You're great help rottalpha,
Its a great move, that circuit may need a little working for 240Vac, I'll look into this when I fit the electro's, but I'll still need a working original switch,
So firstly, I'll look at the mounting of the lever switch, and see if I can mount up a 10amp micro switch with the existing lever assembly.