Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Foreplay III => Topic started by: Mr. Lin on November 18, 2013, 01:50:50 PM

Title: Please help: Foreplay III suddenly lost power to both signal tubes, OD3 still on
Post by: Mr. Lin on November 18, 2013, 01:50:50 PM

Last night I switched my source from CD player to phono preamp, and when I sat down to listen, there was no sound whatsoever.  It didn't take long for me to notice that both 12AU7 tubes were not working, yet there is apprently power because the OD3 tube is still on. 

I checked the fuse and it's fine, I blew out dust and checked for shorts, but no luck.  Time restraints mean I won't be able to take the multi-meter to it for at least a few days, but I'm hoping someone here can possibly shed some light on what I'm looking in the meantime.  It strikes me as a short, but I can't figure out where that could have happened to suddenly and instantly knock out both tubes. 

Thanks in advance to anyone who can offer any help!

- Dave

Title: Re: Please help: Foreplay III suddenly lost power to both signal tubes, OD3 still on
Post by: Doc B. on November 18, 2013, 01:57:29 PM

Sounds like a fault in the DC heater supply. Check the big black rectifier diodes at the back of the power transformer and check all your solder joints between there and the nine pin tube sockets.