2 Monoblock Class Ds Not Working, I'm Lost

[Perry Babin]

Measure DC voltage with a multimeter.

Black probe on the amp's main ground terminal.

Red on pins 1, 4 and 7.

 

[D132]

Pin one has 0.07v

Pin 4 has 0.01v

Pin 7 has 0.067v

 

[Perry Babin]

None of that is enough to drive the protect LED partially on.

With nothing connected to the amp, what's the resistance from each terminal of the protect LED to the primary ground?

What does your meter read when you hold the probes together?

 

[D132]

Open circuit at “RED” terminal
About 850ohms at “LED2” terminal and rises (as if charging a cap)
Probes together are 0.2 ohm

 

[Perry Babin]

From the primary ground again, resistance from there to leg 3 of FET30 and FET31?

 

[D132]

There is no FET30+

 

[Perry Babin]

Near the small transformer in the center of the board?

 

[D132]

Might’ve forgot about those, sorry

Both legs read 0.2ohm (same as probes together)

 

[Perry Babin]

With the amp in 'half-protect', what's the DCV measured directly across the protection LED terminals?

 

[D132]

About 0.7v
Power LED is at about 2.1v

 

[Perry Babin]

Be careful and don't slip. With the amp in 1/2 protect, DCV from the 3rd terminal of FET30 or 31 and the amp's primary ground terminal?