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B2

B2 VFETs

Thankyou, I have the all black heat sink model,the same as your first.

I've got a serial number list of the changeover VFETs, somewhere!

Please tell me your serial numbers when you get a chance


Your Quote :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.
 
brinsmead said:
I wish I'd ordered this manual at the time.
Click to expand...

:drool:

brinsmead said:
Yamaha at its best with this VFET output pair
Click to expand...

Yes indeed! :D

attachment.php
 
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B2 VFETs

That display resolution is a lot better , I'll file that.
good work N

Originally Posted by Dr. Ear
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.

What a great move, I'll look into this
 
B2 VFETs most if not all production

VFET production from Japan most if not all types


List of most VFET production in Japan

2SJ20 / 2SK70 (NEC)
2SK75 (YAMAHA)
2SJ26 / 2SK76 (YAMAHA)
2SJ26A/2SK76A (YAMAHA)
2SK77 (YAMAHA)
2SJ24 / 2SK78 (YAMAHA)
2SK79 (SONY)
2SJ28 / 2SK82 (SONY)
2SJ29 / 2SK89 (HITACHI)
2SJ38 / 2SK98 (YAMAHA)
2SK180 (TOKIN)
2SK181 (TOKIN)
2SK182 (TOKIN)
2SK182E (TOKIN)
 
B2 Switch Cleaner in Ultra sonic bath

I think even the small cleaner would be ok for me, size wise, would you use the powder ?
Our local Aldis have had these advertised from time to time,
 
B2 Relays

I'm giving this a go: The B2 power supply board and fitted socketed relays
 
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No N, no probs there, I had just been toying with the move to put relay sockets on the B2 power supply board for sometime. That was just the finished result.

I’ll do the ultra-sonic cleaning at some point and post results on the B2 switches.

One last thing the power supply board has developed black blotches or spots on the copper tracks, quite noticeful thru the green coating. I remember scraping back copper tracks (underneath the green) on a Sansui Amp and the copper track was black.

I always give these types of issues with PCB’s and in particular the B2 power supply board because of its horizontal position a spray of clear coat solder thru lacquer to seal the terminations and tracks it and this certainly helps when it comes to cleaning the board, a quick scrub up and another light spray and its like new!
regards Rob
 
brinsmead said:
No N, no probs there, I had just been toying with the move to put relay sockets on the B2 power supply board for sometime. That was just the finished result.
Click to expand...

Ah yes, you did say sockets and they look very nice!

I thought about adding sockets too when I changed the relays. And you're not concerned that since the component side of the PCB is facing down and the relays have some mass, they could eventually work their way out of the sockets through vibration? Albeit this is not very likely. Also, the sockets add yet another layer of contact corrosion/resistance.

I’ll do the ultra-sonic cleaning at some point and post results on the B2 switches.
Click to expand...

Yes please! :D

One last thing the power supply board has developed black blotches or spots on the copper tracks, quite noticeful thru the green coating.
Click to expand...


Now you've got me worried! I'll have to take a look and see if this is happening in mine. :yikes:
 
You are absolutely right, you have convinced me, I'm in the process of putting the pcb types back in now! thankyou
 
Pics of B2 Relays returned to normal setup, the socketed idea seemed like a good idea at the time but this power supply board has the bends!
Thankyou asteemed member
 
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Vintage, so your earlier B2 must be less than serial no.4249

In May 1977 they swung away from the blue radiator pt no BA06742 and changed to the black.

To meet overseas standard requirement, ????

Now that a strange statement, maybe someone could enlighten me here
 
No Vintage you're just modest!

Vintage has B2 power supply board on either of yours been discoloured or developed excessive sagging by internal heat and gravity, we now know the
power supply sags in the middle from years of use, but what is interesting is that new boards had a slight bend from the word go, this sagging doesn’t help the adhesion of the glue holding the regulators on either and we have all had reglue these at one time or another. The airflow around these boards is terrible in this position it’s in. I suppose the ultimate life of this PCB is governed by how well it stands up to the rigors of years of operation.
My point is here is Yamaha should have fitted a small exhaust fan in there somewhere to help that airflow.
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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