Rockford fosgate BD1500.1

[mike49504]

I got this in for repair and when i recieved the amp in it was still to hot to touch..

I replaced all of the outputs and checked the MIC4420's ..

If i unsolder the red/black twisted wires ap will power up and idle fine..

If i solder the wires back in the amp draws 60 amps of current..

Any ideas??

 

[mike49504]

Ok All of the outputs are taken out right now..

If i unsolder both sets of red/black twisted wires amp powers up and idles about 3 amps..


If i leave the outputs out of the amp and solder 1 set of the twisted wires back to the board the amp draws 60 amps of current..

Any ideas what might cause this?

 

[Perry Babin]

Assuming that there is nothing wrong with the drive circuit for the power supply FETs, solder bridges on the output pads, defective rectifier, shorted/leaky rail caps, having the red/black wires reversed...

 

[mike49504]

Let me take a pic of the waveform for the power supply fets

 

[mike49504]

OK there are 2 sets of rectifiers i lifted the first set and the current draw went away .. But they test fine out of circuit..

Should i replace them and see if the current draw returns??

 

[Perry Babin]

Did the amp produce rail voltage across both sets of red and black wires?

 

[mike49504]

first set 149.6 volts

Second set of twisted wires -156.9


If i lift the rectifiers amp powers up perfectly if i solder them back in it draws excessive current

 

[Perry Babin]

If you look at the markings on the board on the end of the black and red wires nearest to the power supply FETs and place the black probe on the point marked -HV and the red probe on the point that's marked +HV that one reads positive and the other reads negative?

 

[mike49504]

Correct

 

[Perry Babin]

Try it again with the red and black wires disconnected on the end nearest the power supply FETs.

 

[mike49504]

Ok if i disconnect the twisted wires nearest the power supply fets , I get 0 volts across the wires if i touch the board nearest to the power supply fets i get 149.8 volts

 

[Perry Babin]

With the probes as previously suggested and the rectifiers in the circuit, do both read the same polarity or does one still have reversed polarity?

 

[mike49504]

1 set has 156.0 volts

other set has 150.1 volts

They are both positive readings

 

[Perry Babin]

Do you have the red wires in all of the +HV holes and all of the black wires in the -HV holes?

 

[mike49504]

Ok so far all the wires are solderd back in the board and amp is idling perfectly.. So now im gonna solders the outputs back in and see what i come up with

 

[mike49504]

Ok amp powers up and plays output but the current draw is still to high its about 8 amps of current draw at idle

 

[Perry Babin]

Do you notice anything running hotter than normal?

 

[mike49504]

NO

 

[Perry Babin]

150v is a bit high. Is the voltage less now that you have everything back in the circuit?