Kicker CX1200.1

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warpedhifi

warpedhifi

Member
Joined 2006
#1
This amp has a shorted power supply. This is on the fets:
NXP
psmn3r5
80ps
pem 1425 c2
9226

and

NXP
psmn3r5
80ps
pem 1424 b2
9170

Mouser has them listed as NXP-PSMN3R5-80PS. With out the last two lines. Anybody have an idea what the last two lines are used for? Is there a good substitute for these fets? Thanks
 
#2
Anything past the 80PS would refer to date and batch codes.I would recommend replacing with same from mouser or digikey.

Before you replace the mosfets, check for shorted outputs mosfets & test board w/o mosfets.

Lift R68 from board. With your scope check sawtooth waveform at Pin 5 of the TL494 and drive from Pins 9 & 10 and Pins 3 & 8 of the 18021 Make sure the 68 ohm gate resistors are in value and the drive(squarewave) gets to the mosfet gate pads. Post screenshots if you can.
 
#3
Thanks for the extra info PapaZBill. Somebody has been in this thing before me. One of the spring clips for the outputs is missing. I have a few spares so no worries there. The output fets show to be ok, on initial checks. I will run through your list of checks before going much further.

Thanks again for your help.
 
#5
My mistake!! The PWM is an 8 pin 3843. Pin 4 should have a sawtooth and pin six will be the drive, which is a short duration pulse. I was thinking of the smaller CX which use a traditional push-pull power supply,not the boost converter in the CX1200.1

Sent from my HTC Desire 626 using Tapatalk
 
#6
Back to this amp, I removed the PS Fets, and verified I still had a short (B+ to GND), found the RP Diode (D1) shorted. Replaced it and now have no short when (B+ and GND) are hooked up.

I added a 10 amp fuse for testing purposes, tried to power up and blew the fuse. So with the output fets, and rectifiers, the amp blows the 10 amp fuse.

I the removed the output fets, and left the rectifiers in and the amp will not blow the fuse, but the protection light comes on for about 4 second, then the green led comes on for about 1/2 a second, then repeats.

So, I am guessing the amp is stuck in protection?

Any idea's?
 
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#8
No on Rail voltage, when the new PS FET's were install with no output FET's, it would blow the 10 amp fuse when remote was connected.

I will remove the rectifiers and see if will power up.

The output FET's are good.

I will verify the +/- 15 volts when I get home.

Was thinking since D1 was cracked and shorted, that the amp was possibly wire up backwards?
 
#9
Possibly,usually the diode will short,but remain intact when hooked up reverse polarity. I have seen a number of these amps that have blown D1-1N5402 along with blown PS mosfets,the four 2200uf/35v,The mosfet driver Q5-C2045ES,and ocassionally the gate resistors. If fact I had one today, which I believe is not a result of reverse polarity on the power terminals, but under gauged or copper clad aluminium cables and/or excessive load.

Was there any other damage, such as what I just mentioned?Gate resistors(R11,R3336,37), Q5, capacitors(C2,8,9,10)?

Remove the PS mosfets and probe with you O-scope Pins 4 & 6 of IC16-UC3843 and through Q5 to the gate pads of removed mosfets.Post screen shots if possible.
 
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