Malcolm, thanks, no problem, it had only been 3 or 4 hours! (tap, tap, tap)
jefe1, sorry for the jargon, I don't talk much like that in real life (I hope!), my most recent mentor at work asks me to clarify things better in technical discussions and it kind of spills over into other areas.
I took p-p AC measurements (I don't have a dB meter or the math to convert p-p to dB) at different points in the signal chain using the Yamaha CDC-652, a Kenwood , and the running the Yamaha through the preamp .
Before I read your response I measured the level at the input of C2 and it is the same at R2 & C2. The Yamaha does have a high output.
------------------Yamaha CD--------------Kenwood-----------------Yamaha through Marantz pre-----------------(both channels equal)
unterminated-------4.1v p-p------------------2.7-----------------------------2.7
560ohm term.-------1.4------------------------.4-----------------------------1.6
input at atten.------3.6-----------------------1.8-----------------------------2.5
post-atten unterm.--1.1------------------------.6------------------------------.7vp-p
Either Yamaha direct or through preamp adjusted for 2.7vp-p at input of atten--------------TP112--------TP304
------------------------------------------------------------------------------------------.6vp-p-------.1vp-p----------TP304 had distortion in the sine.
The ground lead is connected.
I did try balancing the levels to 100mv each which kept the signal at TP304 undistorted and the new rear R138 would null but too far to one side, and the back panel R Channel still acts like a level control, null is full ccw.
It's like I have the wrong test points, I don't know, 304 is almost on the edge of the board, 303 is 4" straight across from it, 112 and 111 next to a red filter by 304
.
This decoder has been on the back burner for months. It is the first one I've tried and I was surprised how well it worked right out of the box (except for mis-tracking on some records, but that might be the $2 thrift store records). So, no worries
EDIT: The post took all the spaces out of the test notes , I tried to edit it with dashes, let's see if that works.