U87 (Revision A) in BM800 microphone donor body

[Khron]

4. I have isolated the rails with electrical tape, and I used m1.6 Screws to attach the PCB's without touching anything.

Why would you NOT want the ground pads of the PCB connected to the mic chassis?

 

[RBeTT]

Why would you NOT want the ground pads of the PCB connected to the mic chassis?

The holes of the rails to attach the PCB don't align with the PCB, so I use screws from one side to another [18mm] with nuts and washers which press the PCB against the rail to secure them. Since it isn't properly secure via the holes and might touch other components, I decided to isolate it from the rails and use the ground PCB hole to connect via pin1 [ground].

Isn't that a good idea?

 

[Khron]

The holes of the rails to attach the PCB don't align with the PCB

Are those side-rails cast, or sheet metal? If they're sheet, bend them so the holes line up with the PCB's.