Hifonics Brutus Bxi 2006D in protect

[bigpun4fubu]

ok it would go into protect then removed driver board and would power up fine so had another driver board from another hifonics amp, identical to the original, installed it and would power up fine, then all of a sudden it would blow my 10 amp fuse when powering up checked output transistors in board and legs 2 and 3 on right bank of 6 would read 0 Ohms in circuit found the 2nd fet to be bad other 5 check good but what could cause excessive current draw even if the fets and driverboard are removed, ive removed 6 of the fets, and it powers up fine but seems to draw more than normal current, when i install just the driver board back in circuit it goes back into protect

 

[Perry Babin]

Are you sure that you don't have solder bridges between the pads for the outputs or the driver board?

 

[bigpun4fubu]

solder pads are good but read 0 ohms between pads 2 and 3 on each section

 

[Perry Babin]

Transistors on the other side of the amp can make it appear that there is a short on the side with no transistors.

 

[bigpun4fubu]

ok im going to remove other 6 fets and see, they are reading like the others in circuit ill post results

 

[bigpun4fubu]

solder pads check good on all 12 places after removing all outputs , going to see if goes into protect with driver board installed and check those 6 fets

 

[bigpun4fubu]

powers up fine with driver board in and outputs removed , going to replace all outputs

 

[bigpun4fubu]

replaced outputs the bank of outputs on speaker terminal side 1st fet reads near 0 ohms in circuit but good out of circuit it is Q204

 

[Perry Babin]

Are you sure that only one reads 0 ohms in the board?

0 ohms between which legs?

 

[bigpun4fubu]

Between legs 2and 3 , I'll double check to see if others read funny, could it be the driver board? I could remove it and check the fets again?

 

[Perry Babin]

That transistor is in parallel with other (adjacent) transistors. I'd suspect broken traces or pulled vias if it reads shorted and the others do not.

 

[bigpun4fubu]

vias?

 

[bigpun4fubu]

the 3 in that bank read 0 ohms across legs 2 and 3

 

[Perry Babin]

Vias are the copper feed-throughs that connect the traces on one side of the board to the traces on the other side of the board.

Are either of the other two shorted? If not, there may be an open connection between the drive circuit and the gate of the FET that was preventing the FETs from switching off.

 

[bigpun4fubu]

all 3 read shorted in circuit

 

[Perry Babin]

Are all 3 OK out of the circuit?

Did you check the ones on the other side?

Many times, when you have parallel transistors, you can find the shorted one by measuring the resistance from the gate to the drain. The shorted one will read lower resistance than the other ones.

 

[bigpun4fubu]

the other side checks fine , here is Q203 of the bank what it reads out of circuit, will post other 2 as well

 

[bigpun4fubu]

Q204

 

[Perry Babin]

These are OK. If the 3rd one is similar, it's also OK.

 

[bigpun4fubu]

Q202