hifonics zeus z4400

[mike49504]

I have this amp in for repai. 1 of the outputs was shorted and 3 resistors were also shorted. I replaced the parts Amp is still stuck in protection mode.

So i pulled all outputs even know they tested good Amp is still stuck in protection mode any thoughts?

[Perry Babin]

The transistor that senses over-current in the blown channel may be leaking or shorted. It will likely have one leg connected directly to one end of the emitter resistor.

[mike49504]

Ok i replaced the transistor C3198 and still no luck amp still stuck in protection.

Is there a way to disable the output section to see if the power supply starts up?

[Perry Babin]

Removing the rectifiers should allow the power supply to start.

[mike49504]

I pulled the rectifiers and when trying to power it up the amp does nothing no lights nothing

[Perry Babin]

What's the DC voltage on the gates of the power supply FETs?

[mike49504]

With the rectifiers in the amp i get

leg1:0
leg2:13.90
leg3:0


With the rectifiers out of circuit i get

1:4.96
2:13.90
3:0

It appears to me the amp is powering up with the output section disabled.


So now i have to track down the problem in the output section.

Any idea on where to start since ive already replaced the transistor and the outputs are out of the amp right now

[Perry Babin]

The over-current protection transistors are connected together, possibly via diodes. Find the common connection trace that goes towards the power supply. Desolder and remove the jumper that makes the connection to the power supply.