Help with a Fender SR6300P

[KCman]

Schematic: https://usermanual.wiki/Fender/SR6300P.3224241939/view

Page 3 is the area and model I'm working on. CP 3,4 (speaker) are showing AGND. They are connected to earth ground through the jack being mounted to the chasis. Is that supposed to be floating or connected to earth? I see the AGND connected to the LV-GND. Does that mean Low Voltage ground? But I dont see either connected to earth on the schematic.

When it is connected to earth, it has -60v dc across CP 3,4 and CP 1,2. When I disconnect it I get -18mv across those two. This design is different than what I've seen.

[Jon Snell]

AGround goes to Earth. The centre zero volt point of C26/27, CT is your output.
This configuration was first used by Crown in their MZ series of amplifiers, back many years ago. The rails float.

[Jazz P Bass]

Good reading here on the Grounded Bridge topology.

[Helmholtz]

It's also called "Flying Rails" topology.

Here's an ölder thread on the subject: https://music-electronics-forum.com/...-repair/49979-

[KCman]

Thanks for the info! I started reading the Crown Paper. I'm sure I'll have questions on this amp when I get back into it.