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.
 
“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.
:yikes: 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 ...
 
:yikes: 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 ...
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...
 

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:thumbsup: 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.

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.
 
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? ;)
 
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Hi Pete, this has been a awesome read thank you :bowdown:. 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. :banana:

Now, I hope the next Vfet I am trying to sort out will be so easy...
 

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Hi Pete, this has been a awesome read thank you :bowdown:. 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. :banana:

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
 
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...

Now, I hope the next Vfet I am trying to sort out will be so easy...

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.
 
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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.
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.
 
The preamp has a fault, one of those big Sony IC's has faulted.
OH NO, I hope you find a replacement for that IC. these things are so rare.

Surely does not get as hot as the B-1 and I can run it in summer.
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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