A few weeks ago some arcing noise came out shortly after I switched off my Counterpoint SA-2000 preamp after a long day of use (note that it never really switches off once it is plugged in). Then some nasty burning smell came out. I was lucky to be still in the room when it happened. I unplugged it, opened it up, and found the power transformer very hot but there was no visible sign of any damage in other components. I suspect the transformer got a short inside (the burning smell seemed to have come out of it).
I am the original owner (bought this preamp new in 1995), but it's been in storage for a long time until a few years ago when I resurrected it. I replaced all electrolytic caps, replaced both tubes (6922 and rectifier tube), readjusted all biases and offsets (I did everything myself). It had served me well until it died a sudden death.
I know the transformer will need to be replaced (it'll probably be very hard to find). I'm also worried if it can become a fire hazard since it is always on once it is plugged in. As I understand it, the power switch only turns off the HV supply to the 6922, but all other circuits are on 24/7, including the 6922 heater. The transformer is in use 24/7 once the preamp is plugged in. This sounds pretty scary since there's always HV inside.
I'm wondering if it is worth repairing, or if it's even possible that I can find a replacement part. My theory is that the insulation in the transformer was worn out after many years of continuous use (on 24/7), but I can be wrong, and have not really looked to find out what really happened. Anyone has any insight?
I am the original owner (bought this preamp new in 1995), but it's been in storage for a long time until a few years ago when I resurrected it. I replaced all electrolytic caps, replaced both tubes (6922 and rectifier tube), readjusted all biases and offsets (I did everything myself). It had served me well until it died a sudden death.
I know the transformer will need to be replaced (it'll probably be very hard to find). I'm also worried if it can become a fire hazard since it is always on once it is plugged in. As I understand it, the power switch only turns off the HV supply to the 6922, but all other circuits are on 24/7, including the 6922 heater. The transformer is in use 24/7 once the preamp is plugged in. This sounds pretty scary since there's always HV inside.
I'm wondering if it is worth repairing, or if it's even possible that I can find a replacement part. My theory is that the insulation in the transformer was worn out after many years of continuous use (on 24/7), but I can be wrong, and have not really looked to find out what really happened. Anyone has any insight?
Having a transformer switched on 24/7 shouldn’t be an issue but needs to be secured with a fuse and better even with a heat sensitive fuse like in some transformers is standard. Now finding a replacement shouldn’t be too difficult as well if the voltages are known.
Any chance you over sized the caps? This is a mistake some make on these old pieces and could over heat the xrfmr.
Edcor can make one Custom for you, its worth the effort.
The currents could be calculated easily.
Edcor can make one Custom for you, its worth the effort.
The currents could be calculated easily.
Thanks for the info.
I replaced the caps with the same capacitance, but at higher voltage ratings and with either the longest life or highest temperature variety that I could find (mostly Panasonic or Nichicon).
Edcor's website says the minimum custom order is 25 units, which cannot be cheap, unless they already have the type made for another customer. I suspect even a single unit won't be cheap either, but I'll ping them to find out.
Thanks again.
I replaced the caps with the same capacitance, but at higher voltage ratings and with either the longest life or highest temperature variety that I could find (mostly Panasonic or Nichicon).
Edcor's website says the minimum custom order is 25 units, which cannot be cheap, unless they already have the type made for another customer. I suspect even a single unit won't be cheap either, but I'll ping them to find out.
Thanks again.