Hello Everyone. I'm Jay from Seattle and I'm new to vintage audio, but I've falling quickly down the rabbit hole. I received a turn table recently as a gift which kickstarted my interest in vintage audio equipment. I am particularly fond of mid to late 70s Yamaha gear.
I'm currently recapping by 2nd Yamaha (first was a CR600, currently working on a CR800, and I have a CR820 lined up after this).
I'm learning as I go but it's a slow learning process. Recapping the CR600 went well until a minor hiccup when I installed the main drivers in the wrong locations resulting in having to purchase replacements. It's all back together and working now though.
The CR800 was also going well. I've recapped the preamp board and tested afterwards. I recapped the power board and tested afterwards. I replaced the two filter caps and tested afterwards. I just finished the main board, however, I've run into an issue. Strangely enough, the problem is not with the main amp board, but with the preamp board which was working fine previously. There is no signal leaving the preamp board despite my confirming that signal is coming in (verified with oscilloscope).
I believe the issue is in the power supply board. There is a yellow wire called +BT which runs from the power supply to the preamp. I believe this wire supplies power to the preamp since it's coming from the power supply circuit, but I'm not sure. What voltage should I be measuring here? I'm measuring a fraction of a volt which I don't think is correct.
I have some screen grabs of the relevant boards and circuit diagrams from the service manual. Unfortunately, the scans of the service manual I've found are not great and it's difficult to read a lot of the text. I appreciate any insight anybody might be able to provide. Thanks!
I'm currently recapping by 2nd Yamaha (first was a CR600, currently working on a CR800, and I have a CR820 lined up after this).
I'm learning as I go but it's a slow learning process. Recapping the CR600 went well until a minor hiccup when I installed the main drivers in the wrong locations resulting in having to purchase replacements. It's all back together and working now though.
The CR800 was also going well. I've recapped the preamp board and tested afterwards. I recapped the power board and tested afterwards. I replaced the two filter caps and tested afterwards. I just finished the main board, however, I've run into an issue. Strangely enough, the problem is not with the main amp board, but with the preamp board which was working fine previously. There is no signal leaving the preamp board despite my confirming that signal is coming in (verified with oscilloscope).
I believe the issue is in the power supply board. There is a yellow wire called +BT which runs from the power supply to the preamp. I believe this wire supplies power to the preamp since it's coming from the power supply circuit, but I'm not sure. What voltage should I be measuring here? I'm measuring a fraction of a volt which I don't think is correct.
I have some screen grabs of the relevant boards and circuit diagrams from the service manual. Unfortunately, the scans of the service manual I've found are not great and it's difficult to read a lot of the text. I appreciate any insight anybody might be able to provide. Thanks!
