Marantz 2500 - Identification of Center Tap (CT) Wire

However, I have two machines, a 2600 and a 2500 - both came with the following color sequence installed:
Blue
A quick search on the Internet
shows the colors in this same
sequence.
Blue
Green
Green
Purple
Yellow
Brown
Blue
Gray
Green
Considering the colors on the connectors and the power circuit of the P800 board, it is easy to see that the yellow
wire is connected to "Ground" (earth) and therefore will now be considered the CT (Center Tap) of this side:
The P800 board provides DC (direct current) and AC (alternating current) for all components of the receiver,
except for the power amplifier, which has its own side for each channel (L and R). The circuits are shown below:
Yellow (C.T.)
Dial lamp
panel
Tuner,
preamp &
phono
Oscilloscope