DTS-1500.1

[Hexhclass]

This amp kills the output FETs instantly.The get shot on all three legs.

First pic high side 10v/dv 5/us
next pic low side

 

[Perry Babin]

Try loading the pads gate to source with a small capacitor (0.01uf). The rising side will likely be curved but the falling side should fall vertically.

To clean up the high-side signal, ground the source leg (after confirming that there is no voltage present).

 

[Hexhclass]

Used the caps only on the high side?

high side
gate pad 5v
drain 54.4
source 0.005

Low side
gate -54.8
drain 0.005
source -60.1

 

[Perry Babin]

In general, when testing a drive circuit with no FETs in place, it's good to load it with a capacitor to see if it can drive the capacitive load (much what the FETs will present to the drive circuit).

Load both high and low and look at the waveforms with your scope.

 

[Hexhclass]

10v/dv 5/us

 

[Perry Babin]

Those look OK to me.

 

[Hexhclass]

Any idea what else could cause the FETs to fail?
All FET and drivers were new.

The voltage on the low side remain the same with the caps installed.That's normal?

gate -54.8
drain 0.005
source -60.1