Kicker KX850.4

crazyboi311

Member
2012-02-02 12:22 am
Hi all, I have a Kicker KX850.4 that works fine on channels 1/2 which is amp1 on the amplifier. However on amp2 which is channels 3/4, there will be audio output but the amplifier will shut off when volume is turned up.

I looked inside the amplifier and found a burnt resistor near amp2 speaker terminals. It is R468. Could someone give me the value of that resistor? What would cause this resistor to burn up like this and what else should I look for when fixing this?

I checked all of the output transistors and all of those check out. I did notice however on the TIP41C's and TIP42C's that they were slightly discolored on the amp2 side of output transistors. Thanks in advance!
 

crazyboi311

Member
2012-02-02 12:22 am
I read in the user manual that you can use only one set of inputs which would be amp1 to power all four channels. I checked for the switch in the RCA inputs and those check out fine.

I had another post about this which was a different problem but amp2 inputs don't seem to accept signal to power channels 3/4 but channels 1/2 do.
 

crazyboi311

Member
2012-02-02 12:22 am
I just wanted to make sure that this amp will not give me any more problems in the future. I had it hooked up with all four channels playing with all four inputs into the amp and it started to smoke on the amp2 side which is where i found the burnt resistor.

I will change that and check the others to make sure they are within tolerance as well. Is there anything else i should look out for? Would the TIP41C and TIP42C being defective cause this as well?
 
If everything was working perfectly and R468 burned (for no apparent reason), it would suggest that that channel started to oscillate.

I'm not sure which TIP102/7 you're referring to. I'm assuming that they are the drivers. Are the drivers for channels 3 and 4 discolored?

Did they appear to be clamped tightly against the heatsink? Some had shims (commonly sil-pad material) to make up for the difference in thickness between them and the outputs.