Kicker CXA300.1 No rail, regulated or gate drive.

[rhempz01]

Ok so today i received 7 of these amplifiers in. So this amplifier has a blown T460. No gate and no rail voltage. i removed both the t460 (Which i dont have s ok need to order) I do have the irf3077 which should work fine.
Anyway. gate resistors and r105 4.7k is within tolerance. i dont read a short on the outputs in curcuit. What dhould i check to restore the rail and regulated voltages?

 

[rhempz01]

pcb front and back

 

[rhempz01]

in protection, no rail or regulated. pulled the power supply mosfets. and the 3 2200 25v caps were blown. Only has drive on q12. q13 no drive.

 

[PapaZBill]

W/O Mosfets remove R68, this will disable protection and you can check the drive from the TL494 Pins 9 & 10 through the 18021 Pins 3 and 8. If you have drive to the gate pads of missing Mosfets, replacing the Mosfets should restore the rails. AOT460's are obsolete, you may find a source for them but I wouldn't recommend eBay. The device you mentioned may be suitable but I have no experience to recommend them and may require a different value for the gate resistor. We use a different replacement for the AOT460, which I will post the part number tommorow.

 

[rhempz01]

a pad came free from the board (pad 5) while removing the output ic from the board.
where can i connect this leg to remake this connection?

 

[rhempz01]

pads

 

[PapaZBill]

I believe IC4 is the IRS20957-output driver. If so pin 5 is not tied to anything. I will confirm this when I can.

 

[rhempz01]

value of c99 by outputs?

 

[PapaZBill]

I will check when I get back, maybe a couple of hours

 

[PapaZBill]

C99-470pF

Pin 5 of IC4-IRS20957 is as I thought and is not connected.

 

[rhempz01]

the aot460 replacement mosfet?

 

[PapaZBill]

IRFB3306

 

[rhempz01]

great thanks.

 

[rhempz01]

ok so i replaced the power supply mosfets and the driver.
No audio.
replaced the output transistors and the ird20957s and a top side 100uf 16v cap exploded. c13
2 10r resistors burned up.
r143, r141

 

[PapaZBill]

C13 is the filter cap for the +12VE supply for the Vcc pin 11 IC4-IRS20957. R142 & R143-10 ohm are in line with C13. R141 is a 2 ohm resistor.

Is it possible you have a solder bridge or the IRS20957 was installed backwards?Check C93-457/C and D31-ESD1

This is an unusual failure.

 

[rhempz01]

ok so ordered all parts that i will need on these repairs.
I thought i was doing something wrong, maybe pulling the incorrect resistor for the protection.
the red protection led stays lit.
but the 494 will produce drive.

 

[rhempz01]

c93 reads a short across it in circuit. is it 5uf? how many volts? 50-100v?

 

[PapaZBill]

C93 is a 4.7uF, not sure what the voltage rating is but the cap is on the 12v line for IC4-pin 11 of the IRS20957-VCC. Check IC4,C95. The 12v is coming from Q17-BCP56, ZD8-13v zener. C13-100uF 16v may have shorted.

 

[rhempz01]

c95 reads short. value?

 

[rhempz01]

so i replaced the capacitors that read a short with some from another unit for now. amplifier still is in protection with the resistor r68. The issue is i put new outputs in the amp and it was working came out of protection, had audio, until q19 shorts everytime? the resistors are all good?