JBL EON Mosfet Gate zener?

[lowell]

So there is an 11v zener on the gate of the positive MOSFETs in this PA. Why isn't there a zener on the negative side gates? These devices have a max rating of 20v G/S voltage.

I'm trying to figure out why this came back after repair. I inspected the insulator visually and did not see any "metal shavings." Admittedly they may not be visible with the naked eye. Curious of I should add an 11v zener to the negative side here. I believe it's RG who I learned about this from, a zener to keep the gate from exceeding this rating.

[lowell]

Also, in all 4 of these that I've fixed, it's always been Q370/Q371 that are shorted.

[Enzo]

I am not a circuit maven, but I note the negative side is direct coupled DC, while the positive side are cap coupled.

As the the left pair always being what was failed... The left and right sides are identical circuits, the left is LF_VL+, the woofer positive. The other side woofer negative. I may be all wet, but it occurs to me that if the woofer + wires were somehow more likely to short to ground...