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Yamaha B-1 Vfet monster, restoration

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Well here it is, a 240v version of Yamaha B-1 Vfet amplifier. I am very lucky to have in my hand this extremely rare monster including the UC-1 meter accessory that allows 5 speakers to be connected and controlled from the front panel. 


The Yamaha B-1 is truly one of the best amplifiers Yamaha has made, running a all Vfet circuit and managing to squeeze out 160watt from a pair of giant 2SK77's on each channel. 

Here are the specs. Not bad for the 70's 





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Initial testing is a success, all the jewels are alive and well. 

The parts are ordered and while waiting for delivery will be installing a brand new filtering caps kit.

The filtering caps are enclosed in between the two power transformers which makes replacement not a easy task. 

I have done a kit myself in the past but today installing something special..IMG_2200.thumb.JPG.21c8bbcb69afbfa87e2fb64b74d7e15b.JPG


New kitIMG_2183.thumb.JPG.e77799aa1b4eefc37fe385b6f37d1de5.JPG

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the condition of the Yamaha B-1 is very good. Here is the bottom of the amplifier with the old filtering caps still thereIMG_7929.thumb.JPG.02a5d5410b4d218b04349c16e70b20c8.JPG

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With the new filtering caps in is time to check the boards 1 and 2 of the power supply. The operation of this 2 boards and the board 3 of the power supply is crucial for the B-1. 

Powering up the boards 1 and 2 reveals already some issues. The 40v and -200 show up fine, the 12V and -25 also ok, but the +25v on board 1 shows as 40V!!

That will explain why the meters were not operating properly.  


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Fantastic restoration underway.

Shanks for sharing this job so far .


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Thanks for sharing. I was very happy for the owner when I read that all 500 vfets are ok. 

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