Not as detailed as your restoration work but will do for now
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I am wondering if the YT304 were other v-fets later replaced by the toshibas.
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 ...“Cannot held hand on top of the heat sink” hot.
The unit does not turn off, but if I turn off will not turn back on until cooled a little.
I will check the p-p balance settings again.
YT304's are 2SK77's.I am wondering if the YT304 were other v-fets later replaced by the toshibas.
Maybe @ilimzn would know
I was gonna say... If I would have only paid more attention...YT304's are 2SK77's.
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...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 ...
Where did you come up with all this stuff?
so bunch of "strange" fets and v-fets in there ...and the TJ08 mistery solved. Tried to find informaion on it and I found nothing.
so interesting. I am willing to bet that the Y304/405 devices were from your green boards? correct?
if my assumption is correct, the Y304/405, the TJ08 and the letter ranked J13/K15 devices were used in the earler B-1 units.
Sounds like an excellent idea!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.
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...
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Now, I hope the next Vfet I am trying to sort out will be so easy...
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.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 units needs to be rebuild.
OH NO, I hope you find a replacement for that IC. these things are so rare.The preamp has a fault, one of those big Sony IC's has faulted.
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.Surely does not get as hot as the B-1 and I can run it in summer.