brutus 1600w

[timwebb]

yeah they are all defective what should i be looking for now?

 

[Perry Babin]

Were all of the gate resistors soldered in place and intact when you had all of the FETs in the circuit?

 

[timwebb]

yeah they were in

 

[Perry Babin]

Is it producing rail voltage and clean audio with half of the FETs out of the board?

 

[timwebb]

yeah it is.

 

[Perry Babin]

The driver transistors may be defective.

What does the drive signal on the gate pads for the power supply FETs look like?

 

[timwebb]

the fist one is the power supply the second one is the out put

 

[Perry Babin]

Do you mean from the output transistors?

Is the first one from the power supply FET gate?

On a pad with a transistor or without?

Post one from pin 9 or 10 of the 494 for a reference.

 

[timwebb]

yeah the fist one is the power supply FET gate and the second one is output transistors

 

[Perry Babin]

Post one from pin 9 or 10 of the 494 for a reference.

That's not a good signal for the outputs. I need to see the waveform on pin 9/10 to see if the scope is working right.

 

[timwebb]

i dont see it is it on the vertical board? i think its wiped.

 

[Perry Babin]

It could be on the vertical board. It may be a KA7500 instead of a TLx94.

 

[timwebb]

this is from the two pins

 

[Perry Babin]

The last power supply waveform you posted appears to have been from the center leg instead of the gate leg. Is that correct?

If so, post a photo showing the gate drive signal on the gate pad for the power supply FETs. If the gate drive signals are different for any of the 4 groups of the power supply FETs, post multiple photos.

 

[timwebb]

ok this is before the resistor

 

[timwebb]

resistors dont change the signal do they?

 

[Perry Babin]

Did you change the scope settings?

The signal doesn't appear to indicate driver problems if all 4 groups of FETs had the same signal.

Confirm that all of the gate resistors are intact. Check all of the power supply FETs that are in the circuit. Replace the power supply FETs that were blown and remove the rectifiers. Clamp all power supply FETs to the sink and power the amp up via a 10 amp fuse. Does it power up without blowing the fuse?

Low value resistors won't make a difference to the signal being viewed with the scope.

 

[timwebb]

ok i put the new ones in and removed the rectifiers. now it makes a high pitch noise and get hot

 

[Perry Babin]

How much current was it drawing?

Were the transistors clamped to the heatsink?

 

[timwebb]

i couldn't get a reading my meter is slow.but its pulling hard,it makes a real high noise and doesn't come on man i feel stupid right about now.