Discussion in 'Yamaha' started by rottalpha, Dec 11, 2017.
Not as detailed as your restoration work but will do for now
I used the hole for the connector to power up a suitable preamp (C-1) and just filed it to make it a little wider.
I am wondering if the YT304 were other v-fets later replaced by the toshibas.
Maybe @ilimzn would know
That's definitely not good! During the summer my B-1 gets too hot to keep my hand on the top cover but it never shuts down and will play beautifully for days that way and stay rock solid as far as bias and offset go. I'm thinking the bias still isn't set properly ...
YT304's are 2SK77's.
Where was this schematic published?
I was gonna say... If I would have only paid more attention...
Has anyone seen the YT304?
I mean, at least a photo of them.
After a few more hours of pondering on the thermal circuit I noticed that the supply board 1 that I had installed has a different layout. There is no test points either for the 12, +25 and -25. I refurbish a spare board I have and now the issue has been sorted. The amp still runs hot, but I can turn on, and off normally, even 2 hours of playing. Will do a proper run tomorrow. Pic of the board. There are 3 diodes D617, D618 and D619 that are actually resistors on this board. I had to swap some parts around to the other board. I hope this will be the last of the troubles...
Yes, they were from the green boards. I actually was lucky to come across these boards as spares. Am thinking to start refurbishing the other boards and just not use the green ones.
Sounds like an excellent idea!
I wonder what the serial number of this B-1 was, SN0004?
No , 1004 !
serial number never start at 0
The very first one was 1001
A picture of the B-1 before it became the B-1.
was this a concept?
look at the solid sides and the front plate...no space for the UC/1. I wonder how the rear looked like...probably just a pair of speaker posts.
Hi Pete, this has been a awesome read thank you . So much information. I saw also that you replaced the 10DC1 diodes. What about the A489 and C789 on the 1st board? Did you replace those?
Run the beast all day today and no more issues. Bias and DC balance rock solid.
Now, I hope the next Vfet I am trying to sort out will be so easy...
Glad to hear a happy ending. Congrats!
yes to the dual rectifiers, no to the transistors.
On that board I replaced all 458s, the A561 and C734s. I have a personal bad experince with A561s and i replace them anytime I find them
I have a TA-N7 with the belly open in a box somewhere. Can't wait to get to it at some point. That is what I initially intended to complete over the hollydays, but The B-1 was more intriguing so in the end the B-1 ended up on the bench.
I am not big into integrates, but I would make an exception for that silver beauty of yours. I do have its smaller sibling, the TA-5650. The amp works, the preamp is giving me a nasty static noise. the unit needs to be rebuild.
Personally I prefer the Yamaha Vfet sound but there is something special on the Sony 8650. The preamp has a fault, one of those big Sony IC's has faulted. I hope to get it going just as power amp. Surely does not get as hot as the B-1 and I can run it in summer. The 5650 is nice also with the right speakers.
OH NO, I hope you find a replacement for that IC. these things are so rare.
it better not. The 8650 might be a top-dog for Sony, but it is half the amp B-1 is...in therms of power, thus less heat that needs to disipate.
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