ZX750.1 up in flames.

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I have a ZX750.1 Kicker monoblock, when I hooked it up it was like the forth of July. :eek: I pulled it and replaced it with an other ZX750.1 and works like a champ. I pulled the board and all of the IRF3205's are fried. And this amp is a little different then the last amp I worked on, the (I believe) gate resistors are little black squares with 101 and some with 104 stamped on them. is this the resistance or is it some kinda code? What voltage should i see at the pins? also i dont see any driver transistors anywhere on the board. Ill post some pictures, Perry was a great help on the last one i worked on(still waiting for some parts for over a month)..
and help would be great.

Ok from experience I know the PS is shot but Im not sure what caused it so I and gonna replace the PS, Driver Transistors, and the output transistors and well as the gate resistors. I was told that the 101 stamped on the resistors is 100 ohm?

Heres my parts list any crossable part numbers would be greatly appreciated.

IRF3205 x 8
IRF9640 x 6
IRF640 x 4
100 ohm resistors x 8
ASG23 drivers x 2

Now ive never heard of a ASG23 transistor and wonder if 100 ohm resistors is too much, not enough deadtime?

Ok all you pros out there am I missing anything??

How much should the rail voltage be?

any info at all please
Ok I removed the 8 irf3205's and the 2 transitors i believe are the drivers, cleaned the board up, hooked up some power and am getting 12v on the center leg and 4.4 volts on the end pin (other end pin is ground) ok now I need a cross reference for the driver transistors. Should i switch the 101 ohm resistors with 47's?
Perry was a great help on my last amp so im hoping he can help me out or anyone for that matter.
Use the IRF3205's and switch the gate resistors to 47 ohm. Replace the driver transistors for the power supply as well.

Check all the outputs for any shorted.

Do you have a scope?

From what you said the voltage that you are getting at the solder pads, it looks like your getting gate voltage to the power supply FETS.

Not knowing the history of the amp, either someone reversed polarity on the power supply or you have some shorted outputs.
Very good, am i not supposed to have 12v at the center legs of the fets or 4 volts at the end leg? can i ohm the speaker outputs to see if the outputs are bad, if they were bad wouldnt the amp stay in protect mode?
Im working on the 750 and a 2500 at the same time and with fets removed i get the same voltages on both amps.
Again thank you very much for taking time out of you day to help.
I have not worked on any Kicker amps before.

I have worked on a lot of Rockford and Hifonics amps.

12v on the center leg is OK and 4v on the end is OK if you mean the gate leg of the p/s FET. The 4v is the gate voltage driving the FET.

What outputs does this amp have in it?
That is correct, you can meter from gate to source to see if any are shorted. This test wont tell you if they are leaky but it will tell you if any are shorted.

If you read anything near or close to zero for instance: 2.1 ohms or 3.5 ohms or even .2 ohms or .6 ohms and so on, the FET is shorted.

If any are shorted in the channel, I would advise changing all the outputs in that channel. If you want the amp reliable dont take a chance at reusing old outputs.

Before powering the amp, check your work. Look for missed solder joints, solder bridges, and so on. Use a current limiter inline with the B+, or a small fuse like 10-15 amp. This will help protect the devices if something is wrong still.
Well finally got back to the ZX750 replaced the FETS and drivers. Now Im kicking in and out of protect mode. outputs seem fine. it cycles in and out pretty fast relay doesnt even engage now, before without the obvious blown FETS it would astay on with 12v and 4.5v to the pads, thought I was all good bur thats what I get for thinking.
I know there are various posts about this but here I am anyways.
Ok well I need to make some good clamps for the fets, I used the ones that came with the amp and a couple pair of small vise grips and let it cycle so i could do some testing but apparently they werent clamped good enough and smoked a couple FETS. Or My problem is still in the power supply. Any place in particular I should start? I replaced what I thought were the driver transistors, well Im open to suggestions.
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