Counterpoint SA12 Failure

Last night I spent a few hours diagnosing a right channel noise problem. I am convinced after many cable, tube and speaker swaps and following the noise through the system that the SA12 has faulty component in its right channel.
I don't see any evidence at this point of burns or dielectric leak from any of the caps. I'll check tonight with my meter to see if any of the caps are shorted but I'm thinking it is a diode somewhere in the path that has failed because it is a consistent noise in the channel. I hope its not the MOSFET because I don't think their availability is there.
Any thoughts are more than welcome during this little quest.
HBomb
I don't see any evidence at this point of burns or dielectric leak from any of the caps. I'll check tonight with my meter to see if any of the caps are shorted but I'm thinking it is a diode somewhere in the path that has failed because it is a consistent noise in the channel. I hope its not the MOSFET because I don't think their availability is there.
Any thoughts are more than welcome during this little quest.
HBomb
***WAREMTAE***
Post edited by HBombToo on
Comments
Thanks for the Link Russman. If you look at the quality of the solder job on those very small boards I would hope your impressed. I have not soldered for a long time but was pretty good at it a few years ago. I hope its like riding a bike because this tube thing is all DIY for me.
HBomb catches on fire in a few days:rolleyes:
Twin at his worst and I won't rest untill the BEER HOLE is FULL!
You also might want to try cleaning the tube sockets before getting the soldering iron out.
Let's hope you find the source of the problem asap.
Maurice
No its definetly the right channel of the SA12 and its definetly not a tube. The problem is there is no visible sign of a burned up or leaking cap. It the needle in the Haystack unfortunatly.
HBomb
Maurice
I have a link from a search back when an SA 12 on ebay caught my eye. It's somewhere, but damned if I can find it now. The site focussed on SA 12 repair/ upgrade quotes and some chat.
I remember there was a great deal of mosfet discussion, as gidrah mentioned.
I'll keep looking....
Got it...
http://www.altavistaaudio.com/np100.html
Tour...
Vox Copuli
Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb
"It's easy to get lost in price vs performance vs ego vs illusion." - doro
"There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
"Death doesn't come with a Uhaul." - Dennis Gardner
am I nuts?
HBomb
BTW... Thanks to both gidrah and Tour:D
after further inspection there is a resistor pair missing on the pic. They are right next to the missing cap? Hmmmmm.....Twin
Is that board you posted a replacement stock board or an upgrade board?
Maurice
I really hope it is a bad or leaky cap... I began thinking that if it was the MOSFET it just would not work at all(I hope). The board I posted is the exact board that is in my SA12 less the few components I listed. The basic rebuild is a grand and they remove the MOSFET which I don't want to do. I figure I have this old relic and I want it as original as possible. I called Alto Vista and left a message this morning and inquired if I could purchase a schematic through them. I hope they say yes because that would make life so much easier! I'll just shotgun it and replace every cap on the board.
I'll let ya know. today if they call back.
HBomb
HBomb
Good luck...
Tour...
Vox Copuli
Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb
"It's easy to get lost in price vs performance vs ego vs illusion." - doro
"There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
"Death doesn't come with a Uhaul." - Dennis Gardner
just looking at the HUGE transformer and BIG BADASSED GREY CAPs is a humbling site. I need all the luck I can get here!
HBomb
From all I have read it's a wonderful example of a hybrid... warmth and power in one. But have also read that they are a tad on the tempermental side.
Tour...
Vox Copuli
Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb
"It's easy to get lost in price vs performance vs ego vs illusion." - doro
"There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
"Death doesn't come with a Uhaul." - Dennis Gardner
Just a couple weeks ago when I moved to KC and found it along with the Modulus phono preamp. The modulus works great but your right about the Counterpoint so far in my experience. I hope it does not turn into a money pit. I'm running my RTA8T's and even with the noise in the right channel the setup images beautifully. When I get rid of the noise I'll be able to tell ya how it really sounds.
Big project ahead of me.
HBomb
However, I did receive the pics, "Thankyou", of the carver and am not impressed. IMHO!, good thing you talked to Mr. Grand prior to pulling the trigger. I am not impressed at all when looking at the wiring. Please refer to the attached pic.
My SA12 is very elegant with no pasta!!! and has a huge transformer with 4 massive caps.
Twin
Tour...
Vox Copuli
Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb
"It's easy to get lost in price vs performance vs ego vs illusion." - doro
"There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
"Death doesn't come with a Uhaul." - Dennis Gardner
Evil Twin