I agree The bridge is at the top right of the first board underneath.
One of the popular substitutes for T.M. board are the SCR bridge type and higher end PWM drives by KB Drives.
Max.

 

I am trying to make it a little easier to understand. And I assume that the metal parts would be grounded here, making things safer.

That does make more sense, I agree. But I was under the impression he wanted to do away with it. He said he wanted to completely do away with the existing board, right?

And how does the grounding of metal parts stop the inrush current from violently blowing copper traces of pcb's and throwing off molten metals as switch contacts weld shut? And how is the mains voltage prevented from appearing on low voltage control signals?

Just because metal parts are grounded does not mean something is safe. Have a good look through EN60950 or IEC950 or any of the other electrical safety standards as apply to common mains powered equipment and then explain to me how grounded metal parts alone satisfy even one single requirement of any of those standards. A grounded metal part simply limits the touch voltage to about half the mains voltage. It does not guarantee the user will not come into contact with a hazardous voltage. There is a great deal more to it than you think and given the stakes, better for you not to speculate on somebody else's life.

Sorry I take this so seriously. It is an area i know a lot about given my power electronics experience and not something I can ignore when the result may be lethal.