zastin17
Active Member
"Title EDIT" Boards are F-1159, Not F-1231
So Transistors are something I have not learned much about. And when the fail on the tip of a hat. I just don't know what to do about it...... Lol. "I'M BLIND!"
Anyway, this Sansui Au-666 worked a few years ago. Sounded wonderful! So good infact, I purchased all the caps needed to recap it. Which I still have btw.
I started to recap it several years ago, at this point, all I touched was the driver boards and several other smaller capacitors, I unfortunately installed the PCBs backwards in the Sockets on first power test, and ever since I powered it on, the Driver boards have been dead. I left the Amp on a shelf for several years in frustration.
When the boards where installed backwards, I do remember the 0.5Ohm resistors getting hot, and I needing to replace one of those which opened up at this point, the driver boards no longer worked even installed correct orientation.
Output transistors do not bias or get warm whatsoever anymore either. "No bias"
And 1x UFO transistor gets incredibly hot on the board now. And on the other driver board, the 2sc708 Transistor gets hot. That "Vintage HOT burning smell after 10 seconds or so from the UFO transistor"
Since this is happening on both boards on either channel, it must be the boards themselves, or something common to each channel, But since failure symptoms are different on each board regardless of channel they are installed into, I doubt its a common failure, other than "installing the boards backwards like I did".
I checked pretty much every component expect for Transistors. So it must be a transistor, I hope! i'm just a dumb dumb with them.
I have absolutely no idea what I'm doing with Transistors, I am a Tube guy more or less.
What can I use to replace all the UFO transistors on these Sansui boards? What failure modes makes them get SO hot and pull too much current? Can they short out or partially short?
The transistors I have circled in RED get boiling hot after several seconds now. No bias to Output transistors.
I also managed to tear and damage the Bias transistors in storage, so that's fun.
I'ts such a beautiful unit, I drool over its wonderful construction and layout. JUST GEORGIOUS! I just want it too work damnit!!
I have another Au6500 Sansui, and that thing I use daily, its fully recapped. And, oh my, that's a wonderful SS unit aswell!
So Transistors are something I have not learned much about. And when the fail on the tip of a hat. I just don't know what to do about it...... Lol. "I'M BLIND!"
Anyway, this Sansui Au-666 worked a few years ago. Sounded wonderful! So good infact, I purchased all the caps needed to recap it. Which I still have btw.
I started to recap it several years ago, at this point, all I touched was the driver boards and several other smaller capacitors, I unfortunately installed the PCBs backwards in the Sockets on first power test, and ever since I powered it on, the Driver boards have been dead. I left the Amp on a shelf for several years in frustration.
When the boards where installed backwards, I do remember the 0.5Ohm resistors getting hot, and I needing to replace one of those which opened up at this point, the driver boards no longer worked even installed correct orientation.
Output transistors do not bias or get warm whatsoever anymore either. "No bias"
And 1x UFO transistor gets incredibly hot on the board now. And on the other driver board, the 2sc708 Transistor gets hot. That "Vintage HOT burning smell after 10 seconds or so from the UFO transistor"
Since this is happening on both boards on either channel, it must be the boards themselves, or something common to each channel, But since failure symptoms are different on each board regardless of channel they are installed into, I doubt its a common failure, other than "installing the boards backwards like I did".
I checked pretty much every component expect for Transistors. So it must be a transistor, I hope! i'm just a dumb dumb with them.
I have absolutely no idea what I'm doing with Transistors, I am a Tube guy more or less.
What can I use to replace all the UFO transistors on these Sansui boards? What failure modes makes them get SO hot and pull too much current? Can they short out or partially short?
The transistors I have circled in RED get boiling hot after several seconds now. No bias to Output transistors.
I also managed to tear and damage the Bias transistors in storage, so that's fun.
I'ts such a beautiful unit, I drool over its wonderful construction and layout. JUST GEORGIOUS! I just want it too work damnit!!
I have another Au6500 Sansui, and that thing I use daily, its fully recapped. And, oh my, that's a wonderful SS unit aswell!
Last edited:
